QT5201U wiki - User contributions [en]

A Nanosecond Pulse Generator based on the Reconfigurable Phase-Locked Loop (PLL) Module in Field Programmable Gate Arrays (FPGAs)

2021-05-05T11:52:46Z

Chris: /* Application */

====Members====
Zhang Xing Jian A0226453H, Zhang Jian Ran A0226340R, Chua Rui Ming A0155387U

====Motivation====
Field Programmable Gate Arrays (FPGAs) offer both the advantage of Programmable Logic Devices (PLDs) and Application Specific Integrated Circuits (ASICs) because it possesses the functional flexibility without the simplicity of the former and the functional complexity without the inflexibility of the latter1 (Maxfield, 2008). Furthermore, they are cheap and easy to implement which enables small groups to meet their hardware and software needs1 (Maxfield, 2008). As a result, FPGAs represent a useful option to the production of narrow pulses which finds its role in a myriad of scientific applications2 (Zhu & Wang, 2015). In our context, the generation of narrow pulses is of particular interest in the field of integrated photonics, for example, in the carving of pump light into short pulses for Spontaneous Four-Wave Mixing (SFWM) in silicon microring resonators3 (Ma, 2020). The use of FPGAs to produce narrow pulses provides us with a compact and adjustable pulse generator compatible with integrated photonics technology.

====FPGA Specifications====
=====Product=====

Our FPGA is the "DE0-Nano Development and Education Board" from Terasic (vendor)4 (Terasic Technologies, n.d.). The FPGA utilises Intel Altera's Cyclone IV family, specifically, the Cyclone IV E variant5 (Intel, n.d.). It measures 49 x 75.2mm.

=====Architecture=====

Some features of the make-up of our FPGA includes:
<ul>
<li>22,320 Logic Elements</li>
<li>594 Embedded memory (Kbits)</li>
<li>66 Embedded 18 x 18 multipliers</li>
<li>4 General-purpose PLLs</li>
<li>53 Maximum FPGA I/O pins</li>
</ul>

Its memory features 32MB Synchronous Dynamic Random-Access Memory (SDRAM), 2Kb I2C Electrically Erasable Programmable Read-Only Memories (EEPROM), and it has an on-board 50MHz clock oscillator4 (Terasic Technologies, n.d.).

=====Preview=====

The top and bottom view of the FPGA is featured below respectively4 (Terasic Technologies, n.d.).

[[File:DE0-Nano_layout_top.jpg||400px]]

[[File:DE0-Nano_layout_bot.jpg||400px]]

====Phase-Locked Loop (PLL) Module====

The PLL is the key component to our nanosecond pulse generator and would thus be elaborated upon in the following section. A PLL is a feedback control system that locks on the output signal of an oscillator to an input signal by monitoring and maintaining a phase between them. In Altera's FPGAs, the structure of the PLL is as follows7 (Intel, 2018):
<ul>
<li> A "Phase Frequency Detector" is used to compare the feedback signal with the input signal for any errors between them</li>
<li> A "Charge Pump" is used to convert said error, which manifests itself as an error signal, to a correction current</li>
<li> A "Loop Filter" is used to produce a correction signal from the correction current which is subsequently used to regulate the oscillation frequency of the "Voltage Control Oscillator"</li>
<li> The signal is then fed through the "Feedback Counter" back to the "Phase Frequency Detector" to complete the loop</li>
</ul>
Architecture of Altera's FPGA's PLL7 (Intel, 2018)
 
[[File:Altera Phase-Locked Loop (Altera PLL) IP Core User Guide.png||600px]]

====Methods====

Since the PLL is reconfigurable, the phase, frequency and bandwidth of the PLL output signal may be adjusted in real-time. Logic operations may be executed on two signals produced by the PLL to "carve" out the difference between the two signals into a desired narrow pulse. In Zhu & Wang's paper (2015), they utilised the steps and logic operations to obtain such a pulse:
<ul>

<li> The production of two clock signals A and B of the same frequency, with a phase shift.
<li> The implementation of an A OR B operation to produce clock signal C
<li> The implementation of a D = C XOR A operation to carve out the difference between the two signals to produce the narrow pulse
[[File:2-Figure3-1.png||300px]]
</ul>

In our case, our method deviates from that of Zhu & Wang by implementing a two-step procedure to carve out the pulse. This was achieved simply by skipping the A OR B operation. There are two reasons for our choice: Firstly, this simplifies the problem. Secondly, this way, we obtain two pulses for every set of clock signals- At the front-end and tail-end of the first and second clock signals respectively:

<ul>

<li> The production of two clock signals A and B of the same frequency, with a phase shift.
<li> The implementation of an C = B XOR A operation to produce the narrow pulses
</ul>


[[File:2-Figure3-2.png||350px]]

For the uninitiated, the OR and XOR logic operation can be described by the truth tables and illustrated by the pulsed operations below as referenced from Electronics Hub8,9 (Electronics Hub, 2017)

[[File:OR.jpg||300px]] [[File:OR Pulsed.jpg||300px]]

[[File:XOR.jpg||200px]] [[File:XOR Pulsed.jpg||250px]]

====Results====

=====FPGA Top Design=====

[[File:Top_Design.png|1200px]]

The bulk of our efforts went into the code to configure the Nanosecond Pulse Generator. The FPGA Top Design summarises the outcome of our efforts. Our efforts in its entirety could be found here https://drive.google.com/drive/folders/1weGO1Lyi6H_-A1OadQFYIO-wQEv0VXFj?usp=sharing which will lead to a Google Drive where our files are uploaded in its entirety.

FPGA Performance Characterisation

To characterise the performance of our FPGA, we measured the pulses produced by our FPGA with an oscilloscope (see below). We recall that one of the strengths of the FPGA lies in its adjustability; By adjusting the phase difference between the clock signals, and/or the frequency of the clock signals (which can be adjusted in integer multiples of the clock oscillator), we can obtain different performances (in terms of pulse widths and frequencies) of our pulses.
 
 
=====Best Overall Performance=====

The best overall performance was obtained when the phase difference between the clock signals was set at 11.25 degrees while the frequency of the clock signal is 150MHZ. We obtained a pulse width of 637ps at a frequency of 150MHZ.

[[File:d11.25f150_Best_Performance.png|600px]]

Unfortunately, pushing the FPGA further, we were unable to obtain narrower pulses with that higher frequencies.

[[File:D10f200 Too High Frequency For Pulse Width.png||600px]]

=====Highest Frequency=====

The best frequency performance was obtained when the phase difference between the clock signals was set at 15 degrees while the frequency of the clock signal is 200MHZ. We obtained a pulse width of 746 ps at a frequency of 200MHZ.

[[File:D15f200 _Best _Frequency.png||600px]]

=====Results as a Function of Phase Difference=====

We recall from "Methods" that the way to obtain the pulses was to carve the pulses out from two clock signals. Theoretically, the pulse duration should increase with phase difference for the same frequency. When the phase difference between the clock signals were set at 9, 18 and 37.5 degrees and the frequency of the clock signal is 100MHZ, we obtained a pulse width of 805 ps, pulse width of 1.2 ns and pulse width of 2.27ns respectively.

[[File:D9f100_Function_Of_Phase_Difference_1.png||600px]]

[[File:D18f100_Function_Of_Phase_Difference_2.png||600px]]

[[File:D37.5f100_Function_Of_Phase_Difference_3.png||600px]]

=====Different Configurations For The Same Pulse Width (Theoretically)=====

Theoretically, the pulse duration should remain the same if the phase difference and frequency were increased with the same multiple. The plots below feature such a set of measurements. Setting aside some margin of error for the fact that the increase was not in perfect multiples because of the limited step control of the phase difference, as well as the different frequency response of the circuit, this phenomenon was more or less observed.

[[File:D3.37f50.png||600px]]

[[File:D9f100_Function_Of_Phase_Difference_1.png||600px]]

[[File:D11.25f150_Best_Performance.png||600px]]

=====Summary Table=====

[[File:Table.png||800px]]

====Application====

While we have achieved our goal of creating a working Nanosecond Pulse Generator with our FPGA, it is important to recognise the fact that the pulses created by the FPGA belong to low-power pulse signals between 1.2-3.3V based on the specific I/O standard for the FPGA. Amplification may be required for our FPGA to work with other devices. In this section, a resistance network with a transistor was designed to amplify the output pulses from our FPGA up to 7V for an Electro Optic Modulator (EOM).

As shown in the picture, a TIP29C NPN transistor in our possession was hired as the amplification component. The grounded resistor R4 represents the inner impedance of the EOM. Unfortunately, the 7V half-wave voltage of the EOM required a relatively high current which caused the transistor to overheat. Such issues have to be taken into consideration and represent our future work. Other users would have to consider their own power amplification needs.

[[File:Amplifier.png||400px]]

[[File:Amplifer_2.jpg||300px]]

'''Comment''': Aaaahhhh.. of you want to have this level shifter working at frequencies of a few 100 MHz, you have to use a transistor that is fast enough to do that. The TIP29 certainly is not, it is designed to work at frequencies around a few kHz only and has a gain-bandwidth product of 3MHz. You would find such information typically in data sheets. For the application you have in mind, you really want to have a wideband transistor with a transit frequency of a few GHz. An example would be a [http://www.nxp.com/docs/en/data-sheet/BFR106_CNV.pdf BFR106]

====References====
[1] Maxfield, C. (2008). Fpgas: Instant access. In FPGAs: Instant access (1st ed., pp. 1-12). Burlington, MA: Newnes/Elsevier.

[2] Zhu, Y., & Wang, L. (2015). Design and implementation of nanosecond Pulse generator based ON RECONFIGURATION PLL in FPGA. Proceedings of the 2015 International Conference on Electronic Science and Automation Control. doi:10.2991/esac-15.2015.78

[3] Ma, C. (2020). High-Quality Photon Pair Generation in Silicon Photonic Microring and Its Applications. UC San Diego. ProQuest ID: Ma_ucsd_0033D_19192. Merritt ID: ark:/13030/m5sf83ns. Retrieved from https://escholarship.org/uc/item/7ws930nj

[4] Terasic Technologies. (n.d.). All FPGA boards - Cyclone IV - DE0-Nano development and Education Board. Retrieved March 23, 2021, from https://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=139&No=593&PartNo=3#section

[5] Intel. (n.d.). Cyclone® IV Fpgas devices - Intel® FPGA. Retrieved March 23, 2021, from https://www.intel.sg/content/www/xa/en/products/programmable/fpga/cyclone-iv.html

[6] Intel. (2020). Intel® Quartus® Prime Software Suite. The Intuitive High-Performance Design Environment. Retrieved March 22, 2021, from https://www.intel.com/content/www/us/en/software/programmable/quartus-prime/overview.html

[7] Intel. (2018, December 20). Altera phase-locked Loop (ALTERA PLL) ip core user guide. Retrieved March 23, 2021, from https://www.intel.com/content/www/us/en/programmable/documentation/mcn1401782837027.html

[8] Electronics Hub. (2017, December 24). Digital logic or gate. Retrieved March 29, 2021, from https://www.electronicshub.org/digital-logic-or-gate/#OR_Gate

[9] Electronics Hub. (2017, December 24). Exclusive or Gate(XOR-Gate). Retrieved March 29, 2021, from https://www.electronicshub.org/exclusive-or-gatexor-gate/#XOR_Gate

Here

2021-05-05T11:35:02Z

Chris:

=Silicon Coating Speed Calibrating=
We have tentatively tried to operate a RF sputtering machine<ref>https://www.dentonvacuum.com/products-technologies/magnetron-sputtering/</ref> to deposit a thin layer of silicon onto the surface of an optical window made of BK7 glass. This machine generates a powerful (>100 Watt) RF electric field to ionize the Argon gas in the chamber. This ionized argon gas will then bombard the sputtering targets (silicon in this case), and the sputtered atoms from the targets will in turn form the deposition layer on the substrate.

The deposition rate (how fast does the layer grow, usually in nm/s) depends not only on the input RF power, but is also related to the distance between the sputtering targets and the substrate sample as well as the surface area of the sample. This deposition rate needs to be measured as accurate as possible to ensure correct layer thickness.

We took an optical method approach by observing the change in transmission spectrum for different deposition time (which should translate to different thickness if a constant deposition rate is assumed). We deposited a few different thin-film samples, with deposition time of 6000s, 8000s, 10000s, 12000s. The transmission spectrum of each sample is measured with a spectrophotometers. From the measured spectra we roughly estimated a deposition rate of 0.034nm/s (2.05nm/min).

[[File:Silicon-thickness.png|800px]] [[File:Substrate-BK7.png|720px]]

'''Comment''': Hmmm, good to have a characterization of the growth speed :) However, the transmission of the BK7 window in the near-visible regime seems a bit low...? I also don't understand the scale on the right vertical axis...

Wavemeter based on interferometer

2021-05-05T11:20:00Z

Chris: /* Oscilloscope */

This project aims to build a wavemeter which can be used to measure laser in our lab precisely.

Team: Qin Qichen, Zhao Qi, Zhang Zhao.

==Introduction==
There are many methods to measure the wavelength of laser. One easy idea is to use an interferometer. The fringes of interference is associated with wavelength of laser. So by comparing it with the result of a reference laser the wavelength can be measured. Now there is something wrong with the wavemeter in our lab. Hence, we aim to build a wavemeter to measure laser in our lab. The range of wavelength our wavemeter can detect aim to be around 1100nm - 1700nm, determined by optics. A precision around 100MHz is expected.

==Theory==
Michelson interferometer is a good tool to measure the length if there is a good laser. Similarly, it can also be used to measure the unknown wavelength of a laser by calculating the ratio of wavelengths between the unknown and a known laser. Here we use a 1550nm laser as our reference. By counting zeros in the signal, we can get the ratio between wavelengths.

[[File:Optical_setup.jpg|500px|thumb|Optical setup of wavemeter]]
In Michelson interferometer<ref>https://en.wikipedia.org/wiki/Michelson_interferometer</ref>, an input beam is splitted into two and reflected back by their respective mirror. The two beams with a phase difference caused by travelling different optical path lengths would form an interference pattern after overlapping. If we change the optical path length difference of the two beams, i.e. change the length of one arm by moving the mirror, the interference pattern would change simultaneously.

Consider the planar wave case, the two reflected beams could be written as <math>E_1=\frac{A_0}{2} e^{i(\omega t+knx_0)}</math> and <math>E_2=\frac{A_0}{2} e^{i(\omega t+knx_0-2knx(t))}</math>, where <math>A_0</math> is the amplitude of the input beam, <math>\omega</math> is the angular frequency, <math>k</math> is the wavenumber, <math>n</math> is the refractive index of air, <math>x_0</math> is the length of one constant arm and <math>x(t)</math> is the length difference changing with time of the other arm.

Then the total electrical field at the output would be

<math>E=\frac{A_0}{2} e^{i(\omega t+knx_0)} (1+e^{-2iknx(t)})</math>

The intensity would thus be

<math>I= \frac{1}{2} \epsilon E E^*=\frac{\epsilon A_0^2}{2} (1+cos(2knx(t))</math>

For <math>x(t)=x</math>, the number of zero-crossings of the interference pattern would be <math>N=\frac{2knx}{\pi}</math>. According to this equation, we can relate the ratio of wavelengths of two lasers <math>\lambda_1</math> and <math>\lambda_2</math> with their number of zero-crossings as

<math>\frac{N_1}{N_2} =\frac{\frac{2k_1nx}{\pi}}{\frac{2k_2nx}{\pi}} =\frac{k_1}{k_2} =\frac{\lambda_2}{\lambda_1}</math>.

==Components==
[[File:pic1.jpg|500px|thumb|Wavemeter setup]]
===Optics===
;List of all the optic components used:

:Silver mirror x6 (to adapt broadband laser that might be measured)

:BB1-E04 mirror x2 (for 1550nm reference laser)

:50/50 Beamsplitter 1100nm-1600nm x1

:C220-c Aspherical lens x2 (for fiber input of two lasers)

:TS975M-M01B Retroreflector x2

:f50mm lens x1 (for unknown-laser detector)

:f35mm lens x1 (for 1550nm detector)

:PDA10CS-EC detector x1

:PDA50B-EC detector x1

===Air track===
The whole setup including air track and optics is built on a 750mmx750mm breadboard table. The aluminum linear stage is 550mmx50mm with a 150mmx50mm sledge sliding on its V-shape surface. The friction is reduced by producing an air cushion between the two surfaces using 10 small holes on the bottom of sledge that is provided with compressed air via a silicon tube. Two springs are attached to both ends of the sledge and fixed around two long screws. Besides the force provided by springs when reflected from ends, the kinetic energy loss is also compensated by a small push pull solenoid fixed on one end of the stage. Two optical switches are mounted on board to detect the signal when sledge reaches ends by a piece of paper fixed on sledge, controlling the solenoid.

===Signal Process===
The circuit for processing signal. The signals generated by photodetectors are small and dc biased. To enable our counter, we need to transfer the signal to a 0-5V signal. We first use a high pass filter to get rid of the dc part. Then a monolithic amplifier is used to amplify the ac signal before we put it into our comparator. The comparator is used to generate the 5V signal. The output port of LM339AN can be seen as a transistor so use a pullup resistor connected to 5V we can accomplish it.

<gallery widths=500px heights=400px>
File:Signal circuit.png|800px|thumb|signal processing circuit

</gallery>

'''Comment''': Congratulation, obviously it worked ;) However, the MAR amplifiers would need a resistor at the positive supply feeding in DC current for them to actually amplify the signal. Maybe you did not need it in the case here... Also, keep in mind these amplifiers are internally terminated with 50 Ohm to ground: The additional resistors with 150 Ohm at their input only lowers the total input impedance to 1/(1/50+1/150)=37.5Ohm, so you likely have a higher cutoff frequency than what you thought. But hey, it worked!

;Components we use:
[[File:Signal board.jpg|200px|right|thumb|board for this circuit]]
:2 Resistors for high pass filter <math>150\Omega</math>
:2 Capacitors for high pass filter <math>0.1\mu F</math>
:2 Resistors for low pass filter <math>3.3k\Omega</math>
:2 Capacitors for low pass filter <math>1\mu F</math>
:1 Quad Differential Comparators LM339AN
:2 Monolithic Amplifiers MAR-3SM+
:1 Voltage Regulator L7805SCV
:2 Potentiometer

===Control Circuit===
The schematic of the circuit for control is shown below. Arduino UNO<ref>https://store.arduino.cc/usa/arduino-uno-rev3</ref> board is used to control and count signals and should be connected to a computer to power it and get reading. Two optical switches are used to get rid of signal change when car gets pushed back. The optical switch 0 is also used to turn on/off solenoid. A push pull solenoid is used to push the car and compensate for energy loss in motion.

<gallery widths=500px heights=400px>
File:wavemeter circuit.png|thumb|right|800px|control circuit

</gallery>

;Components we use:

:2 Optical switches OPB881T55Z

:1 Push-Pull solenoid TAU0730TM-14

:2 Optical detectors PDA10CS-EC and PDA50B-EC

:2 Resistors for photodiode <math>240\Omega</math>

:2 Resistors for phototransistor <math>6.7k\Omega</math>

:1 Resistor for transistor base <math>1k\Omega</math>

:1 Transistor 2N2222A

:1 diode to protect 1N4007G

<gallery widths=300px heights=200px>
File:wavemeter_optical_switch.jpg|thumb|300px|optical switch
File:wavemeter_solenoid.jpg|thumb|300px|push pull solenoid

</gallery>

==Program==
The main program consists of two parts.

[[File:wavemeter_picture_forprogram.png|500px|thumb|right|when the optical switch is blocked]]
One is to control the car. When the car passes across the optical switch 0 and move to the edge, the program will receive a signal change from OS0 and then turn on the solenoid. Then the small solenoid will be driven and push the car. So the position of optical switch 0 should be suitable because if the solenoid is on when the car moves towards the edge, the car will be decelerated. The right timing is to push the car when the spring is compressed to the minimum length. This can be done by changing the position of OS0.

The other part is two counters, for reference and measured laser. We make use of Arduino UNO to do this. There are three timers inside Atmega328P<ref>https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf</ref>(this chip is the core controller of Arduino UNO). Timer0 and Timer2 are 8bit timer and Timer1 is a 16bit timer. Normally when you enable the timer, it will use the internal 16MHz clock and count the clock signal. For example, if you set no prescale(which means the clock frequency is 16/1 = 16Mhz), the timer register will increase every 1/16M second. Then it will be cleared when its value overflows. For 8 bit timer the range of register is from 0 to 255. Then we use these timers to count the rising in the interferometer signal. As tested before, it should be noticed the frequency should be no more than 3MHz and the transition must cross 2.5V and Vpp must be larger than 1V. Otherwise, the timer will lose signals.

As shown here, the initial state of the wavemeter should be like this, the car should be between two optical switches. That's because the setting in code. The circuit does not know where the car is and it only knows whether the car passes across optical switches. So I set the initial state variable as 1 which means the car is between two optical switches and the counters are working. The program will pause the counter by cutting off power for counters when the car passes across optical switches. Because we want to get rid of the signal when the car changes its direction.

==Result==
Here we use 1550nm laser as our reference, 701nm laser as a measured laser to test the wavemeter. We need to clarify here that these two lasers are available in our lab now but not locked. So we do not know the real number of the wavelength. There are two methods to count fringes. One way is to use an oscilloscope to save fringes and process data on PC. The other way is to use our Arduino board to count and send counts to the computer automatically. Here we first use an oscilloscope to test our setup. Our result shows the ratios from two methods are in accordance, which shows the counter we made works at least.
===Signal===
Here is the signal from detector directly.
<gallery widths=500px heights=400px>
File:Wavemeter_signal.jpg|thumb|right|800px|Signal from wavemeter
</gallery>

As said in electronic section, we use a circuit to amplify and reshape the signal. After processing, the signal is shown below:

<gallery widths=500px heights=400px>
File:Wavemeter_output.jpg|thumb|right|800px|Signal from wavemeter
</gallery>

===Oscilloscope===
Here we save data from an oscilloscope(the signal from detector). Because the sampling time is much shorter than the period of car moving, we can treat the frequency of sine signal unchanged. We can fit the line and get the frequency of signal directly. Then, the ratio gives us the ratio of laser frequency.
In a 100 <math>\mu s</math> time duration, two beat signals are sine fitted and the ratio of resulted frequency is the ratio of two lasers' frequency.
<gallery widths=500px heights=400px>
File:wavemeter Plot.png|thumb|right|800px|1550nm&701nm plot
</gallery>

<gallery widths=500px heights=400px>
File:wavemeter Y1.png|thumb|right|800px|701nm fitting
</gallery>

<gallery widths=500px heights=400px>
File:wavemeter Y2.png|thumb|right|800px|1550nm fitting
</gallery>

<math>\frac{1550}{701}=2.2111</math> and from fitted line we get ratio <math>\frac{4.698}{2.12}=2.2160</math>

'''Comment''': Whenever possible, try to specify an uncertainty of your measurement result. In this method of determining the wavelength, it would likely be the uncertainty of +/-1 in the zero transitions during a fixed periode of the test beam. Not sure how your code exactly works, but you may or may not have to consider an uncertainty of +/-1 in the reference counts as well. The latter uncertainty you could remove if you count a fixed number of reference events, and use it to control a gate window for the test counts....

===Arduino counter===
For Arduino counter, because we do not limit the start point of counting(do not make sure two signals have the same phase), counts may be different. There is also fluctuation in counts. So we read 20000 samples and plot the histogram here.
<gallery widths=500px heights=400px>
File:Wavemeter_histogram_of_sampling.png|thumb|right|800px|1550nm&701nm plot
</gallery>
The average result shows a ratio of wavelength <math>2.2157</math>, the same as the result from the fitting method.

==Future work==
There exist several problems to be solved here.

First, the wavelength of our laser is unknown. So we can only get a ratio and can not get an absolute value. We plan to use a 804nm laser as reference in the future because this laser is locked and we can read the wavelength from the wavemeter in our lab.

Second, in the result from Arduino board, the result shows discrete distribution. The space between boxes is limited by max counts set in Arduino code. If we want to get a higher resolution, we need higher max counts, which means a longer sampling time.

Third, It is necessary to write an interface window to make this system easier to use. This window should allow people choose max counts and average numbers.

Our project gives a preliminary result here. It can be improved by solving these problems.

==History==
===Mar 9===
We find the optics for our wavemeter and order the retroreflectors. The design files of our air track and car are sent to Bob.

We test our pull-push solenoids and optical switch. We aim to use Arduino UNO as our controller. Today we test using an optical switch to generate the voltage signal.

===Mar 16===
Arduino UNO is tested to do the counter. We try to use the simple functions provided by Arduino compiler environment to do this. The idea is to detect the rising of the signal. So I make the comparison between two samplings with a given time interval to see if there is a rising. The problem is this method is too slow. The function provided by the compiler is actually a bunch of pieces of the atomical operations. The time interval set by function is also limited by an internal timer of the board.

There are two types of timers in this Arduino UNO board, which are actually provided by the microcontroller chip Atmega328P. The chip has an internal clock with 16MHz frequency. Theoretically, our signal is around 1MHz if assuming the speed of our car is around 1m/s. So it seems feasible if we use the internal clock to do this counter. Need to read documents and search to see how other people do this.
===Mar 29===
Sampling and comparing the signal is not good enough to do the counter. This method is useful only for very slow signals such as 1kHz. If the frequency of our signal is 1MHz, if we want to do the counting by comparing the sampling, our sampling should be at least 2MHz to capture all rising. But when we compare the executing of those codes can waste a lot of time, then we will miss a lot of rising signal. So it is not a good idea.

I check some useful documents. It seems use port manipulation will minimize the time used to do the read and write. I can also use the interrupt which is associated with a timer to do some tasks. A good instruction about this can be seen on the sites below.

https://www.arduino.cc/en/Reference/PortManipulation

https://www.instructables.com/Arduino-and-Port-Manipulation/

https://www.instructables.com/Arduino-Timer-Interrupts/

http://gammon.com.au/interrupts
===Apr 5===
Bob finished the mechanical work. We get our air track and car. We are beginning to set up the air track.
===Apr 6===
We use compressed air in our lab as our air source. we put the car on the air track. But their are two problems here.

First, the air port of the car is on one side so the pipe may touch some optics. So we need an L shape adapter to make the pipe vertical.

Then, the pipe connected to the car is hard, which means when we move the car it will be forced by the pipe. We need to find a softer pipe,

Murray suggests using a 90 curved copper pipe to connect the car.
===Apr 7===
Tried the method in https://www.arduino.cc/reference/en/language/functions/external-interrupts/attachinterrupt/. Use the signal to trigger the interrupt. I use two signals from the function generator to test. The result is it can detect a signal no more than 100kHz. So this method is not good and we still need to find a way to do the counting.

Make one 90 curved copper pipe and try it. But it is so heavy that the car tilts and touches one side of the air track. It is better not to use this. We find a curved plastic pipe which is better to do this. We also borrow a soft pipe and the compression spring from Kai's Lab(the spring we bought before is too hard, the k is too high).
[[File:Wavemeter_airtrack.jpeg|300px|thumb|right|Air track and car for the wavemeter]]

===Apr 8===
The clock frequency is designed to be 16MHz so theoretically signal with a lower frequency than 16MHz can all be counted. It also reminds me that the timer inside the chip can be chosen as the counter. Choosing the timer inside needs an understanding of the register inside the microcontroller. Basically, registers can store some bits and the value of these bits can determine how the chip works. Details about this can be found in https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf

Use this method as our counter. It is found the board can work pretty well when we use two MHz signals as input from a function generator. Now the control part can be added in.
===Apr 9===
The picture shows the basic idea about our circuit. [[File:Wavemeter_test_circuit1.jpeg|300px|thumb|right|The circuit for our wavemeter]]Two optical switches and one solenoid are connected to our Arduino UNO board. We want to make sure the board stops counting when the car moves to the edge. So the optical switch 1 is connected to the INT1 pin of Atmega328p which is used to request an interrupt<ref>http://gammon.com.au/interrupts</ref> to pause counting when the signal changes. The optical switch 0 is connected to INT0 and can also pause counting. INT0 is also used to control solenoid. This pull push solenoid is on when the car reaches the edge and pushes the car back. We use a simple transistor to control it.

The result shows our board can count the risings in signal and when one counting reaches a maximum value we set before it will show and then clear the counting.

Use two signals from a function generator as input. One is 1.2MHz and the other one is 1MHz. The counting from our board is 5120000 and 4266671. The ratio is 1.19999878125. The maximum value of counting, 5120000, can be changed to get different precision.

===Apr 12===
Test the circuit which controls the car. Change the position of optical switch 0 a little to make the car keep moving. The result shows the car can move at least several hours if the air pressure is suitable.

===Apr 14===
Use a PCB board found in the workshop and make a board instead of using the breadboard in case someone messes up our circuit.
[[File:wavemeter_circuit_v2.jpg|300px|right|thumb|circuit of wavemeter]]
===Apr 16===
Finish setting up for optics preliminarily. Now we use 701 laser to test our wavemeter.
===Apr 19===
Check the signal from detectors. The signal from 1550nm reference laser is not stable while the signal from 701nm laser is stable. That is because we set up 1550 first and now the optics is optimized for 701 laser. When the car moves, the reference signal shows an oscillating. It is also a problem that the signals are too small for our counter to work. We need to process the signal first.
===Apr 21===
Because the interference is not ideal so there is a DC voltage in our signal. We test a high pass filter to do this.
===Apr 23===
Make a board to process the signal. The board is designed to filter dc signal and amplified the sine signal. The output is designed to be a 0-5V square wave which is more suitable for our counters.
===Apr 26===
Test the wavemeter today. The circuit and counter work well but the result is wrong. The problem is from 1550 reference laser. Because this signal is not stable. When the signal is very small, the counter will miss counts. Then the counts for 1550 will be smaller than the actual number which means our result will be smaller than the real value. So need to check our setup.
===Apr 28===
Check the setup and set smaller max counts. Now the board can work well.

==Reference==
<references />

==Code==
Here is the code for Arduino IDE.
<pre>
//these two lines are used to disable the timer0 defination used in Arduino board. wiring.c should be changed.
//signal <3MHz 2.5V crossing Vpp>1V
#define _DISABLE_ARDUINO_TIMER0_INTERRUPT_HANDLER_
#include <wiring.c>

volatile int counter_0_ovf = 0; //use timer 0 8bit count 256*ovf pin4 detector 0
volatile int counter_1_ovf = 0; //use timer 1 16bit count 65536*ovf pin5 detector 1
volatile long counter0_ovf_result = 0;//store ovf value
volatile long counter1_ovf_result = 0;//store ovf value
volatile int counter0 = 0;//timer0 value
volatile int counter1 = 0;//timer1 value

bool car_state = true; //state of car, initial value true
bool counter0_state = false;//state flag for counter0, initial value false
bool counter1_state = false;//state flag for counter1, initial value false

int state = 0;

long MaxCount0_ovf = 10240; //define max ovf value for counter0
long MaxCount1_ovf = MaxCount0_ovf*256/65536; //define max ovf value for counter1

void counter_reset(){
//clear counter
TCNT0 = 0;
TCNT1 = 0;
//clear ovf_value
counter_0_ovf = 0;
counter_1_ovf = 0;
}

void setup() {
//initila serial setting
Serial.begin(9600);

cli();//disable all interrupt

//enable timer 0 and timer 1 by clearing PRTIM
PRR&=~((1<<PRTIM0)|(1<<PRTIM1));

//set timer 0
TCCR0B|=(1<<CS00)|(1<<CS01)|(1<<CS02); //External clock source on T0 pin4. Clock on rising edge.
//clear WGM to set normal mode
TCCR0A&=~((1<<WGM01)|(1<<WGM00));
TCCR0B&=~(1<<WGM02);
TIMSK0|= (1<<TOIE0); //overflow interrupt is enabled

//set timer 1
TCCR1B|=(1<<CS10)|(1<<CS11)|(1<<CS12); //External clock source on T1 pin5. Clock on rising edge.
//clear WGM to set normal mode
TCCR1A&=~((1<<WGM11)|(1<<WGM10));
TCCR1B&=~((1<<WGM13)|(1<<WGM12));
TIMSK1|= (1<<TOIE1); //overflow interrupt is enabled

//set external interrupt for coil control and pause counting, signal source: optical switch0. use INT0
EIMSK &=~ (1<<INT0);//disable
EICRA |= (1<<ISC00)|(1<<ISC01);//The rising edge of INT0 generates an interrupt request
EIFR |= (1<<INTF0);//clear the flag
EIMSK |= (1<<INT0);//enable

//set external interrupt pause counting, signal source: optical switch1. use INT1
EIMSK &=~ (1<<INT1);//disable
EICRA |= (1<<ISC10)|(1<<ISC11);//The rising edge of INT1 generates an interrupt request
EIFR |= (1<<INTF1);//clear the flag
EIMSK |= (1<<INT1);//enable

//initial the coil(default: off)
DDRB |= (1<<DDB0);//pin set as output to control coil
PORTB&=~(1<<PORTB0);//off

sei();//enable interrupt
}

ISR(INT0_vect){
//toggle the state of car
car_state = !car_state;
//turn on/off the counter
PRR^=((1<<PRTIM0)|(1<<PRTIM1));
//toggle the coil
PORTB^=(1<<PINB0);
}

ISR(INT1_vect){
//toggle the state of car
car_state = !car_state;
//toggle the switch to control counter
PRR^=((1<<PRTIM0)|(1<<PRTIM1));
}

ISR(TIMER0_OVF_vect){
counter_0_ovf++;
if (counter_0_ovf<MaxCount0_ovf){
counter0_state = false;//counter0 not ready
}
else{
counter0_ovf_result = counter_0_ovf;
counter1_ovf_result = counter_1_ovf;
counter0_state = true;//counter0 ready
counter0 = 0;
counter1 = TCNT1;//restore counter1 value
counter_reset();
}
}

ISR(TIMER1_OVF_vect){
counter_1_ovf++;
if (counter_1_ovf<MaxCount1_ovf){
counter1_state = false;//counter1 not ready
}
else{
counter1_ovf_result = counter_1_ovf;
counter0_ovf_result = counter_0_ovf;
counter1_state = true;//counter1 ready
counter1 = 0;
counter0 = TCNT0;//restore counter0 value
counter_reset();
}
}

void loop() {
state = (car_state&&(counter0_state||counter1_state));
switch(state){
case 0:
//not ready
break;
case 1:
//result ready
//send counts to computer
Serial.println("counts pin, pin4 and pin5");
Serial.println((counter0_ovf_result)*256+counter0);
Serial.println((counter1_ovf_result)*65536+counter1);
//clear state in case the board repeats output
counter0_state = false;
counter1_state = false;

break;
}
}
</pre>

Here is the jupyter notebook Python2 code for getting result:
<pre>

import serial
import numpy as np
from matplotlib import pyplot as plt

arduino = serial.Serial('COM5', 9600, timeout=.1)

def group_sampling(lines):
counter0=[]
counter1=[]
i = 0
while i+2 < len(lines):
if lines[i] == 'counts pin, pin4 and pin5':
counter0.append(float(lines[i+1]))
counter1.append(float(lines[i+2]))
i += 1
return [np.array(counter0),np.array(counter1)]

w0 = 1550e-9 #wavelength of reference laser

#read data
Maxsampling = 20000 #groups of sampling
lines=[]
i = 0
for i in list(range(3*Maxsampling)):
read = arduino.readline()[:-2]
if read:
lines.append(read)

[counter0,counter1] = group_sampling(lines)

ratio = counter0/counter1
ratio.sort()
ratio = ratio[10000:-1000]

result = w0*ratio
f = 299792458/result/1e6

sample = result

fig, ax = plt.subplots()

num_bins = 50

# the histogram of the data
n, bins, patches = ax.hist(sample, num_bins, density = True)

# add a 'best fit' line
#y = ((1 / (np.sqrt(2 * np.pi) * sigma)) *
# np.exp(-0.5 * (1 / sigma * (bins - mu))**2))
#ax.plot(bins, y, '--')
ax.set_xlabel('Wavelength')
ax.set_ylabel('Probability density')
ax.set_title(r'Histogram of sampling: $\mu={:.2f}$, $\sigma={:.2f}$'.format(np.mean(sample),np.std(sample)))

# Tweak spacing to prevent clipping of ylabel
fig.tight_layout()
plt.show()

</pre>

Wavemeter based on interferometer

2021-05-05T11:15:06Z

Chris: /* Signal Process */

This project aims to build a wavemeter which can be used to measure laser in our lab precisely.

Team: Qin Qichen, Zhao Qi, Zhang Zhao.

==Introduction==
There are many methods to measure the wavelength of laser. One easy idea is to use an interferometer. The fringes of interference is associated with wavelength of laser. So by comparing it with the result of a reference laser the wavelength can be measured. Now there is something wrong with the wavemeter in our lab. Hence, we aim to build a wavemeter to measure laser in our lab. The range of wavelength our wavemeter can detect aim to be around 1100nm - 1700nm, determined by optics. A precision around 100MHz is expected.

==Theory==
Michelson interferometer is a good tool to measure the length if there is a good laser. Similarly, it can also be used to measure the unknown wavelength of a laser by calculating the ratio of wavelengths between the unknown and a known laser. Here we use a 1550nm laser as our reference. By counting zeros in the signal, we can get the ratio between wavelengths.

[[File:Optical_setup.jpg|500px|thumb|Optical setup of wavemeter]]
In Michelson interferometer<ref>https://en.wikipedia.org/wiki/Michelson_interferometer</ref>, an input beam is splitted into two and reflected back by their respective mirror. The two beams with a phase difference caused by travelling different optical path lengths would form an interference pattern after overlapping. If we change the optical path length difference of the two beams, i.e. change the length of one arm by moving the mirror, the interference pattern would change simultaneously.

Consider the planar wave case, the two reflected beams could be written as <math>E_1=\frac{A_0}{2} e^{i(\omega t+knx_0)}</math> and <math>E_2=\frac{A_0}{2} e^{i(\omega t+knx_0-2knx(t))}</math>, where <math>A_0</math> is the amplitude of the input beam, <math>\omega</math> is the angular frequency, <math>k</math> is the wavenumber, <math>n</math> is the refractive index of air, <math>x_0</math> is the length of one constant arm and <math>x(t)</math> is the length difference changing with time of the other arm.

Then the total electrical field at the output would be

<math>E=\frac{A_0}{2} e^{i(\omega t+knx_0)} (1+e^{-2iknx(t)})</math>

The intensity would thus be

<math>I= \frac{1}{2} \epsilon E E^*=\frac{\epsilon A_0^2}{2} (1+cos(2knx(t))</math>

For <math>x(t)=x</math>, the number of zero-crossings of the interference pattern would be <math>N=\frac{2knx}{\pi}</math>. According to this equation, we can relate the ratio of wavelengths of two lasers <math>\lambda_1</math> and <math>\lambda_2</math> with their number of zero-crossings as

<math>\frac{N_1}{N_2} =\frac{\frac{2k_1nx}{\pi}}{\frac{2k_2nx}{\pi}} =\frac{k_1}{k_2} =\frac{\lambda_2}{\lambda_1}</math>.

==Components==
[[File:pic1.jpg|500px|thumb|Wavemeter setup]]
===Optics===
;List of all the optic components used:

:Silver mirror x6 (to adapt broadband laser that might be measured)

:BB1-E04 mirror x2 (for 1550nm reference laser)

:50/50 Beamsplitter 1100nm-1600nm x1

:C220-c Aspherical lens x2 (for fiber input of two lasers)

:TS975M-M01B Retroreflector x2

:f50mm lens x1 (for unknown-laser detector)

:f35mm lens x1 (for 1550nm detector)

:PDA10CS-EC detector x1

:PDA50B-EC detector x1

===Air track===
The whole setup including air track and optics is built on a 750mmx750mm breadboard table. The aluminum linear stage is 550mmx50mm with a 150mmx50mm sledge sliding on its V-shape surface. The friction is reduced by producing an air cushion between the two surfaces using 10 small holes on the bottom of sledge that is provided with compressed air via a silicon tube. Two springs are attached to both ends of the sledge and fixed around two long screws. Besides the force provided by springs when reflected from ends, the kinetic energy loss is also compensated by a small push pull solenoid fixed on one end of the stage. Two optical switches are mounted on board to detect the signal when sledge reaches ends by a piece of paper fixed on sledge, controlling the solenoid.

===Signal Process===
The circuit for processing signal. The signals generated by photodetectors are small and dc biased. To enable our counter, we need to transfer the signal to a 0-5V signal. We first use a high pass filter to get rid of the dc part. Then a monolithic amplifier is used to amplify the ac signal before we put it into our comparator. The comparator is used to generate the 5V signal. The output port of LM339AN can be seen as a transistor so use a pullup resistor connected to 5V we can accomplish it.

<gallery widths=500px heights=400px>
File:Signal circuit.png|800px|thumb|signal processing circuit

</gallery>

'''Comment''': Congratulation, obviously it worked ;) However, the MAR amplifiers would need a resistor at the positive supply feeding in DC current for them to actually amplify the signal. Maybe you did not need it in the case here... Also, keep in mind these amplifiers are internally terminated with 50 Ohm to ground: The additional resistors with 150 Ohm at their input only lowers the total input impedance to 1/(1/50+1/150)=37.5Ohm, so you likely have a higher cutoff frequency than what you thought. But hey, it worked!

;Components we use:
[[File:Signal board.jpg|200px|right|thumb|board for this circuit]]
:2 Resistors for high pass filter <math>150\Omega</math>
:2 Capacitors for high pass filter <math>0.1\mu F</math>
:2 Resistors for low pass filter <math>3.3k\Omega</math>
:2 Capacitors for low pass filter <math>1\mu F</math>
:1 Quad Differential Comparators LM339AN
:2 Monolithic Amplifiers MAR-3SM+
:1 Voltage Regulator L7805SCV
:2 Potentiometer

===Control Circuit===
The schematic of the circuit for control is shown below. Arduino UNO<ref>https://store.arduino.cc/usa/arduino-uno-rev3</ref> board is used to control and count signals and should be connected to a computer to power it and get reading. Two optical switches are used to get rid of signal change when car gets pushed back. The optical switch 0 is also used to turn on/off solenoid. A push pull solenoid is used to push the car and compensate for energy loss in motion.

<gallery widths=500px heights=400px>
File:wavemeter circuit.png|thumb|right|800px|control circuit

</gallery>

;Components we use:

:2 Optical switches OPB881T55Z

:1 Push-Pull solenoid TAU0730TM-14

:2 Optical detectors PDA10CS-EC and PDA50B-EC

:2 Resistors for photodiode <math>240\Omega</math>

:2 Resistors for phototransistor <math>6.7k\Omega</math>

:1 Resistor for transistor base <math>1k\Omega</math>

:1 Transistor 2N2222A

:1 diode to protect 1N4007G

<gallery widths=300px heights=200px>
File:wavemeter_optical_switch.jpg|thumb|300px|optical switch
File:wavemeter_solenoid.jpg|thumb|300px|push pull solenoid

</gallery>

==Program==
The main program consists of two parts.

[[File:wavemeter_picture_forprogram.png|500px|thumb|right|when the optical switch is blocked]]
One is to control the car. When the car passes across the optical switch 0 and move to the edge, the program will receive a signal change from OS0 and then turn on the solenoid. Then the small solenoid will be driven and push the car. So the position of optical switch 0 should be suitable because if the solenoid is on when the car moves towards the edge, the car will be decelerated. The right timing is to push the car when the spring is compressed to the minimum length. This can be done by changing the position of OS0.

The other part is two counters, for reference and measured laser. We make use of Arduino UNO to do this. There are three timers inside Atmega328P<ref>https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf</ref>(this chip is the core controller of Arduino UNO). Timer0 and Timer2 are 8bit timer and Timer1 is a 16bit timer. Normally when you enable the timer, it will use the internal 16MHz clock and count the clock signal. For example, if you set no prescale(which means the clock frequency is 16/1 = 16Mhz), the timer register will increase every 1/16M second. Then it will be cleared when its value overflows. For 8 bit timer the range of register is from 0 to 255. Then we use these timers to count the rising in the interferometer signal. As tested before, it should be noticed the frequency should be no more than 3MHz and the transition must cross 2.5V and Vpp must be larger than 1V. Otherwise, the timer will lose signals.

As shown here, the initial state of the wavemeter should be like this, the car should be between two optical switches. That's because the setting in code. The circuit does not know where the car is and it only knows whether the car passes across optical switches. So I set the initial state variable as 1 which means the car is between two optical switches and the counters are working. The program will pause the counter by cutting off power for counters when the car passes across optical switches. Because we want to get rid of the signal when the car changes its direction.

==Result==
Here we use 1550nm laser as our reference, 701nm laser as a measured laser to test the wavemeter. We need to clarify here that these two lasers are available in our lab now but not locked. So we do not know the real number of the wavelength. There are two methods to count fringes. One way is to use an oscilloscope to save fringes and process data on PC. The other way is to use our Arduino board to count and send counts to the computer automatically. Here we first use an oscilloscope to test our setup. Our result shows the ratios from two methods are in accordance, which shows the counter we made works at least.
===Signal===
Here is the signal from detector directly.
<gallery widths=500px heights=400px>
File:Wavemeter_signal.jpg|thumb|right|800px|Signal from wavemeter
</gallery>

As said in electronic section, we use a circuit to amplify and reshape the signal. After processing, the signal is shown below:

<gallery widths=500px heights=400px>
File:Wavemeter_output.jpg|thumb|right|800px|Signal from wavemeter
</gallery>

===Oscilloscope===
Here we save data from an oscilloscope(the signal from detector). Because the sampling time is much shorter than the period of car moving, we can treat the frequency of sine signal unchanged. We can fit the line and get the frequency of signal directly. Then, the ratio gives us the ratio of laser frequency.
In a 100 <math>\mu s</math> time duration, two beat signals are sine fitted and the ratio of resulted frequency is the ratio of two lasers' frequency.
<gallery widths=500px heights=400px>
File:wavemeter Plot.png|thumb|right|800px|1550nm&701nm plot
</gallery>

<gallery widths=500px heights=400px>
File:wavemeter Y1.png|thumb|right|800px|701nm fitting
</gallery>

<gallery widths=500px heights=400px>
File:wavemeter Y2.png|thumb|right|800px|1550nm fitting
</gallery>

<math>\frac{1550}{701}=2.2111</math> and from fitted line we get ratio <math>\frac{4.698}{2.12}=2.2160</math>

===Arduino counter===
For Arduino counter, because we do not limit the start point of counting(do not make sure two signals have the same phase), counts may be different. There is also fluctuation in counts. So we read 20000 samples and plot the histogram here.
<gallery widths=500px heights=400px>
File:Wavemeter_histogram_of_sampling.png|thumb|right|800px|1550nm&701nm plot
</gallery>
The average result shows a ratio of wavelength <math>2.2157</math>, the same as the result from the fitting method.

==Future work==
There exist several problems to be solved here.

First, the wavelength of our laser is unknown. So we can only get a ratio and can not get an absolute value. We plan to use a 804nm laser as reference in the future because this laser is locked and we can read the wavelength from the wavemeter in our lab.

Second, in the result from Arduino board, the result shows discrete distribution. The space between boxes is limited by max counts set in Arduino code. If we want to get a higher resolution, we need higher max counts, which means a longer sampling time.

Third, It is necessary to write an interface window to make this system easier to use. This window should allow people choose max counts and average numbers.

Our project gives a preliminary result here. It can be improved by solving these problems.

==History==
===Mar 9===
We find the optics for our wavemeter and order the retroreflectors. The design files of our air track and car are sent to Bob.

We test our pull-push solenoids and optical switch. We aim to use Arduino UNO as our controller. Today we test using an optical switch to generate the voltage signal.

===Mar 16===
Arduino UNO is tested to do the counter. We try to use the simple functions provided by Arduino compiler environment to do this. The idea is to detect the rising of the signal. So I make the comparison between two samplings with a given time interval to see if there is a rising. The problem is this method is too slow. The function provided by the compiler is actually a bunch of pieces of the atomical operations. The time interval set by function is also limited by an internal timer of the board.

There are two types of timers in this Arduino UNO board, which are actually provided by the microcontroller chip Atmega328P. The chip has an internal clock with 16MHz frequency. Theoretically, our signal is around 1MHz if assuming the speed of our car is around 1m/s. So it seems feasible if we use the internal clock to do this counter. Need to read documents and search to see how other people do this.
===Mar 29===
Sampling and comparing the signal is not good enough to do the counter. This method is useful only for very slow signals such as 1kHz. If the frequency of our signal is 1MHz, if we want to do the counting by comparing the sampling, our sampling should be at least 2MHz to capture all rising. But when we compare the executing of those codes can waste a lot of time, then we will miss a lot of rising signal. So it is not a good idea.

I check some useful documents. It seems use port manipulation will minimize the time used to do the read and write. I can also use the interrupt which is associated with a timer to do some tasks. A good instruction about this can be seen on the sites below.

https://www.arduino.cc/en/Reference/PortManipulation

https://www.instructables.com/Arduino-and-Port-Manipulation/

https://www.instructables.com/Arduino-Timer-Interrupts/

http://gammon.com.au/interrupts
===Apr 5===
Bob finished the mechanical work. We get our air track and car. We are beginning to set up the air track.
===Apr 6===
We use compressed air in our lab as our air source. we put the car on the air track. But their are two problems here.

First, the air port of the car is on one side so the pipe may touch some optics. So we need an L shape adapter to make the pipe vertical.

Then, the pipe connected to the car is hard, which means when we move the car it will be forced by the pipe. We need to find a softer pipe,

Murray suggests using a 90 curved copper pipe to connect the car.
===Apr 7===
Tried the method in https://www.arduino.cc/reference/en/language/functions/external-interrupts/attachinterrupt/. Use the signal to trigger the interrupt. I use two signals from the function generator to test. The result is it can detect a signal no more than 100kHz. So this method is not good and we still need to find a way to do the counting.

Make one 90 curved copper pipe and try it. But it is so heavy that the car tilts and touches one side of the air track. It is better not to use this. We find a curved plastic pipe which is better to do this. We also borrow a soft pipe and the compression spring from Kai's Lab(the spring we bought before is too hard, the k is too high).
[[File:Wavemeter_airtrack.jpeg|300px|thumb|right|Air track and car for the wavemeter]]

===Apr 8===
The clock frequency is designed to be 16MHz so theoretically signal with a lower frequency than 16MHz can all be counted. It also reminds me that the timer inside the chip can be chosen as the counter. Choosing the timer inside needs an understanding of the register inside the microcontroller. Basically, registers can store some bits and the value of these bits can determine how the chip works. Details about this can be found in https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf

Use this method as our counter. It is found the board can work pretty well when we use two MHz signals as input from a function generator. Now the control part can be added in.
===Apr 9===
The picture shows the basic idea about our circuit. [[File:Wavemeter_test_circuit1.jpeg|300px|thumb|right|The circuit for our wavemeter]]Two optical switches and one solenoid are connected to our Arduino UNO board. We want to make sure the board stops counting when the car moves to the edge. So the optical switch 1 is connected to the INT1 pin of Atmega328p which is used to request an interrupt<ref>http://gammon.com.au/interrupts</ref> to pause counting when the signal changes. The optical switch 0 is connected to INT0 and can also pause counting. INT0 is also used to control solenoid. This pull push solenoid is on when the car reaches the edge and pushes the car back. We use a simple transistor to control it.

The result shows our board can count the risings in signal and when one counting reaches a maximum value we set before it will show and then clear the counting.

Use two signals from a function generator as input. One is 1.2MHz and the other one is 1MHz. The counting from our board is 5120000 and 4266671. The ratio is 1.19999878125. The maximum value of counting, 5120000, can be changed to get different precision.

===Apr 12===
Test the circuit which controls the car. Change the position of optical switch 0 a little to make the car keep moving. The result shows the car can move at least several hours if the air pressure is suitable.

===Apr 14===
Use a PCB board found in the workshop and make a board instead of using the breadboard in case someone messes up our circuit.
[[File:wavemeter_circuit_v2.jpg|300px|right|thumb|circuit of wavemeter]]
===Apr 16===
Finish setting up for optics preliminarily. Now we use 701 laser to test our wavemeter.
===Apr 19===
Check the signal from detectors. The signal from 1550nm reference laser is not stable while the signal from 701nm laser is stable. That is because we set up 1550 first and now the optics is optimized for 701 laser. When the car moves, the reference signal shows an oscillating. It is also a problem that the signals are too small for our counter to work. We need to process the signal first.
===Apr 21===
Because the interference is not ideal so there is a DC voltage in our signal. We test a high pass filter to do this.
===Apr 23===
Make a board to process the signal. The board is designed to filter dc signal and amplified the sine signal. The output is designed to be a 0-5V square wave which is more suitable for our counters.
===Apr 26===
Test the wavemeter today. The circuit and counter work well but the result is wrong. The problem is from 1550 reference laser. Because this signal is not stable. When the signal is very small, the counter will miss counts. Then the counts for 1550 will be smaller than the actual number which means our result will be smaller than the real value. So need to check our setup.
===Apr 28===
Check the setup and set smaller max counts. Now the board can work well.

==Reference==
<references />

==Code==
Here is the code for Arduino IDE.
<pre>
//these two lines are used to disable the timer0 defination used in Arduino board. wiring.c should be changed.
//signal <3MHz 2.5V crossing Vpp>1V
#define _DISABLE_ARDUINO_TIMER0_INTERRUPT_HANDLER_
#include <wiring.c>

volatile int counter_0_ovf = 0; //use timer 0 8bit count 256*ovf pin4 detector 0
volatile int counter_1_ovf = 0; //use timer 1 16bit count 65536*ovf pin5 detector 1
volatile long counter0_ovf_result = 0;//store ovf value
volatile long counter1_ovf_result = 0;//store ovf value
volatile int counter0 = 0;//timer0 value
volatile int counter1 = 0;//timer1 value

bool car_state = true; //state of car, initial value true
bool counter0_state = false;//state flag for counter0, initial value false
bool counter1_state = false;//state flag for counter1, initial value false

int state = 0;

long MaxCount0_ovf = 10240; //define max ovf value for counter0
long MaxCount1_ovf = MaxCount0_ovf*256/65536; //define max ovf value for counter1

void counter_reset(){
//clear counter
TCNT0 = 0;
TCNT1 = 0;
//clear ovf_value
counter_0_ovf = 0;
counter_1_ovf = 0;
}

void setup() {
//initila serial setting
Serial.begin(9600);

cli();//disable all interrupt

//enable timer 0 and timer 1 by clearing PRTIM
PRR&=~((1<<PRTIM0)|(1<<PRTIM1));

//set timer 0
TCCR0B|=(1<<CS00)|(1<<CS01)|(1<<CS02); //External clock source on T0 pin4. Clock on rising edge.
//clear WGM to set normal mode
TCCR0A&=~((1<<WGM01)|(1<<WGM00));
TCCR0B&=~(1<<WGM02);
TIMSK0|= (1<<TOIE0); //overflow interrupt is enabled

//set timer 1
TCCR1B|=(1<<CS10)|(1<<CS11)|(1<<CS12); //External clock source on T1 pin5. Clock on rising edge.
//clear WGM to set normal mode
TCCR1A&=~((1<<WGM11)|(1<<WGM10));
TCCR1B&=~((1<<WGM13)|(1<<WGM12));
TIMSK1|= (1<<TOIE1); //overflow interrupt is enabled

//set external interrupt for coil control and pause counting, signal source: optical switch0. use INT0
EIMSK &=~ (1<<INT0);//disable
EICRA |= (1<<ISC00)|(1<<ISC01);//The rising edge of INT0 generates an interrupt request
EIFR |= (1<<INTF0);//clear the flag
EIMSK |= (1<<INT0);//enable

//set external interrupt pause counting, signal source: optical switch1. use INT1
EIMSK &=~ (1<<INT1);//disable
EICRA |= (1<<ISC10)|(1<<ISC11);//The rising edge of INT1 generates an interrupt request
EIFR |= (1<<INTF1);//clear the flag
EIMSK |= (1<<INT1);//enable

//initial the coil(default: off)
DDRB |= (1<<DDB0);//pin set as output to control coil
PORTB&=~(1<<PORTB0);//off

sei();//enable interrupt
}

ISR(INT0_vect){
//toggle the state of car
car_state = !car_state;
//turn on/off the counter
PRR^=((1<<PRTIM0)|(1<<PRTIM1));
//toggle the coil
PORTB^=(1<<PINB0);
}

ISR(INT1_vect){
//toggle the state of car
car_state = !car_state;
//toggle the switch to control counter
PRR^=((1<<PRTIM0)|(1<<PRTIM1));
}

ISR(TIMER0_OVF_vect){
counter_0_ovf++;
if (counter_0_ovf<MaxCount0_ovf){
counter0_state = false;//counter0 not ready
}
else{
counter0_ovf_result = counter_0_ovf;
counter1_ovf_result = counter_1_ovf;
counter0_state = true;//counter0 ready
counter0 = 0;
counter1 = TCNT1;//restore counter1 value
counter_reset();
}
}

ISR(TIMER1_OVF_vect){
counter_1_ovf++;
if (counter_1_ovf<MaxCount1_ovf){
counter1_state = false;//counter1 not ready
}
else{
counter1_ovf_result = counter_1_ovf;
counter0_ovf_result = counter_0_ovf;
counter1_state = true;//counter1 ready
counter1 = 0;
counter0 = TCNT0;//restore counter0 value
counter_reset();
}
}

void loop() {
state = (car_state&&(counter0_state||counter1_state));
switch(state){
case 0:
//not ready
break;
case 1:
//result ready
//send counts to computer
Serial.println("counts pin, pin4 and pin5");
Serial.println((counter0_ovf_result)*256+counter0);
Serial.println((counter1_ovf_result)*65536+counter1);
//clear state in case the board repeats output
counter0_state = false;
counter1_state = false;

break;
}
}
</pre>

Here is the jupyter notebook Python2 code for getting result:
<pre>

import serial
import numpy as np
from matplotlib import pyplot as plt

arduino = serial.Serial('COM5', 9600, timeout=.1)

def group_sampling(lines):
counter0=[]
counter1=[]
i = 0
while i+2 < len(lines):
if lines[i] == 'counts pin, pin4 and pin5':
counter0.append(float(lines[i+1]))
counter1.append(float(lines[i+2]))
i += 1
return [np.array(counter0),np.array(counter1)]

w0 = 1550e-9 #wavelength of reference laser

#read data
Maxsampling = 20000 #groups of sampling
lines=[]
i = 0
for i in list(range(3*Maxsampling)):
read = arduino.readline()[:-2]
if read:
lines.append(read)

[counter0,counter1] = group_sampling(lines)

ratio = counter0/counter1
ratio.sort()
ratio = ratio[10000:-1000]

result = w0*ratio
f = 299792458/result/1e6

sample = result

fig, ax = plt.subplots()

num_bins = 50

# the histogram of the data
n, bins, patches = ax.hist(sample, num_bins, density = True)

# add a 'best fit' line
#y = ((1 / (np.sqrt(2 * np.pi) * sigma)) *
# np.exp(-0.5 * (1 / sigma * (bins - mu))**2))
#ax.plot(bins, y, '--')
ax.set_xlabel('Wavelength')
ax.set_ylabel('Probability density')
ax.set_title(r'Histogram of sampling: $\mu={:.2f}$, $\sigma={:.2f}$'.format(np.mean(sample),np.std(sample)))

# Tweak spacing to prevent clipping of ylabel
fig.tight_layout()
plt.show()

</pre>

Main Page

2021-04-13T10:38:37Z

Chris: /* Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well) */

Project wiki for the Module QT5201U (Quantum control technology) - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

Deadline for the reports will be 30 April 23:59SGT!

==Project proposals==
===[[Wavemeter based on interferometer]]===
Basically, we are now trying to build a wavemeter based on Michelson interferometer. The goal is to measure laser with a wavelength from 1200nm to 1800nm which can be used for these lasers in our lab. This project consists of work about optics and electronic control. The control system is mainly implemented by using a Arduino UNO board and some basic circuits.

===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Control over the atomic spins within certain molecules by NMR technique]]===
NMR has been the workhorse for the experimental implementation of quantum protocols, allowing exquisite control of systems up to seven qubits in size. However, there exists some experimental limitations in terms of the cross-talk, coupled evolution, instrumental errors and so on.
Thanks to the current advanced pulse techniques, we can reduce these influences and extend this technique to a new stage that the experimental limits can be neglected. In this experiment, we try to use composite pulses to compensate RF field strength variations and frequency offsets.

===[[Optical control of TMDCs valley pseudospin qubits]]===
Quantum dots or single electron transistors, allow for individual control of single charge or spin. In addition, some semiconductor monolayers possess a sizeable direct bandgap of ≈1.5–2 eV in the optical range allowing electrostatic confinement and optical manipulation of carriers. Therefore, we try to adopt the method of this theoretical paper, and see if we can control single qubit or couple 2 qubits optically.

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

===[[Microwave control of superconducting cavity and qubit]]===
This project aims to perform a trial pre-experiment based on the cQED architecture including simulation, calibration, microwave control pulse programming, and so on. The 3D superconducting cavity sample is anchored to the MXC flange inside the Bluefors dilution refrigerator to reach a temperature of around 10mK. On the other hand, the generation of microwave control pulses and the acquisition of output signals are handled by a QM quantum control device, connecting the sample via the control lines and the output lines accordingly. Hence, we can realize several bosonic states via cavity driving and qubit control.

===[[A Nanosecond Pulse Generator based on the Reconfigurable Phase-Locked Loop (PLL) Module in Field Programmable Gate Arrays (FPGAs)]]===
Field Programmable Gate Arrays (FPGAs) are digital integrated circuits (ICs) that contain blocks of logic and interconnects which can be configured and reconfigured even after it is being deployed "in the field". This enables flexible tunability in the function of FPGA-based devices. We seek to replicate the works of Zhu & Wang (2015) to utilise the Phase-Locked Loop (PLL) module in FPGA to implement a nanosecond pulse generator with adjustable frequency and pulse width. Our circuit was designed with Quartus Prime.

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1.2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1.2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1.2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1.2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021||[https://youtu.be/WfP5mahZrWU Optical modulators, part 2]

|-
| 15.2.2021
|[https://youtu.be/m_F4DOHMNeU Homodyne detection techniques] || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques. These techniques, similar to their radiofrequency counterparts, rely on multiplying field amplitudes.

|-
| 1.3.2021
|[https://youtu.be/YkVlxxucLuA Frequency control of laser systems, part 1]
| rowspan="2" |Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions or solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.
|-
| 2.3.2021
|[https://youtu.be/72aVZwI4BHU Frequency control of laser systems, part 2]

|-
| 8.3.2021
|[https://youtu.be/jolUa_EGZEs Interface to computers]
| High level interfacing between computers and electronic hardware: Standard device languages; some serial protocols, some aspects of microcontrollers and FPGAs

|-
| 15.3.2021
|[https://youtu.be/1S0EAnooQMc Pulses in quantum control]
| Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. This covers how they are used, and present a few techniques to generate such control pulses

|-
| 22.3.2021
|[https://youtu.be/PHx-da7RLE8 High voltage techniques]
| Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|-
|12.4.2021
|[https://youtu.be/K0U9ySRyvjs Control loops]
| Many experimental activities in controlling quantum systems require the control of classical systems, like the temperature stabilization of some device, or the frequency stabilization of a laser. This lecture gives a brief overview of some simple control concepts.

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in LaTeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>
* Should you miss any module or functionality of this wiki, please contact me (Christian Kurtsiefer).

Main Page

2021-04-05T08:03:04Z

Chris:

Project wiki for the Module QT5201U (Quantum control technology) - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

Deadline for the reports will be 30 April 23:59SGT!

==Project proposals==
===[[Wavemeter based on interferometer]]===
Basically we are now trying to build a wavemeter which can measure wavelength from 1200nm to 1800nm because the measurement tool for these lasers is not available now in our lab. It is based on Michelson interferometer.
===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Control over the atomic spins within certain molecules by NMR technique]]===
NMR has been the workhorse for the experimental implementation of quantum protocols, allowing exquisite control of systems up to seven qubits in size. However, there exists some experimental limitations in terms of the cross-talk, coupled evolution, instrumental errors and so on.
Thanks to the current advanced pulse techniques, we can reduce these influences and extend this technique to a new stage that the experimental limits can be neglected. In this experiment, we try to use composite pulses to compensate RF field strength variations and frequency offsets.

===[[Optical control of TMDCs valley pseudospin qubits]]===
Quantum dots or single electron transistors, allow for individual control of single charge or spin. In addition, some semiconductor monolayers possess a sizeable direct bandgap of ≈1.5–2 eV in the optical range allowing electrostatic confinement and optical manipulation of carriers. Therefore, we try to adopt the method of this theoretical paper, and see if we can control single qubit or couple 2 qubits optically.

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

===[[Microwave control of superconducting cavity and qubit]]===
This project aims to perform a trial pre-experiment based on the cQED architecture including simulation, calibration, microwave control pulse programming, and so on. The 3D superconducting cavity sample is anchored to the MXC flange inside the Bluefors dilution refrigerator to reach a temperature of around 10mK. On the other hand, the generation of microwave control pulses and the acquisition of output signals are handled by a QM quantum control device, connecting the sample via the control lines and the output lines accordingly. Hence, we can realize several bosonic states via cavity driving and qubit control.

===[[A Nanosecond Pulse Generator based on the Reconfigurable Phase-Locked Loop (PLL) Module in Field Programmable Gate Arrays (FPGAs)]]===
Field Programmable Gate Arrays (FPGAs) are digital integrated circuits (ICs) that contain blocks of logic and interconnects which can be configured and reconfigured even after it is being deployed "in the field". This enables flexible tunability in the function of FPGA-based devices. We seek to replicate the works of Zhu & Wang (2015) to utilise the Phase-Locked Loop (PLL) module in FPGA to implement a nanosecond pulse generator with adjustable frequency and pulse width. Our circuit was designed with Quartus Prime.

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1.2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1.2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1.2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1.2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021||[https://youtu.be/WfP5mahZrWU Optical modulators, part 2]

|-
| 15.2.2021
|[https://youtu.be/m_F4DOHMNeU Homodyne detection techniques] || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques. These techniques, similar to their radiofrequency counterparts, rely on multiplying field amplitudes.

|-
| 1.3.2021
|[https://youtu.be/YkVlxxucLuA Frequency control of laser systems, part 1]
| rowspan="2" |Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions or solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.
|-
| 2.3.2021
|[https://youtu.be/72aVZwI4BHU Frequency control of laser systems, part 2]

|-
| 8.3.2021
|[https://youtu.be/jolUa_EGZEs Interface to computers]
| High level interfacing between computers and electronic hardware: Standard device languages; some serial protocols, some aspects of microcontrollers and FPGAs

|-
| 15.3.2021
|[https://youtu.be/1S0EAnooQMc Pulses in quantum control]
| Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. This covers how they are used, and present a few techniques to generate such control pulses

|-
| 22.3.2021
|[https://youtu.be/PHx-da7RLE8 High voltage techniques]
| Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in LaTeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>
* Should you miss any module or functionality of this wiki, please contact me (Christian Kurtsiefer).

Main Page

2021-04-05T08:01:44Z

Chris:

Project wiki for the Module QT5201U (Quantum control technology) - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

Deadline for the reports will be 30 April 23:59SGT!

==Project proposals==
===[[Wavemeter based on interferometer]]===
Basically we are now trying to build a wavemeter which can measure wavelength from 1200nm to 1800nm because the measurement tool for these lasers is not available now in our lab. It is based on Michelson interferometer.
===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Control over the atomic spins within certain molecules by NMR technique]]===
NMR has been the workhorse for the experimental implementation of quantum protocols, allowing exquisite control of systems up to seven qubits in size. However, there exists some experimental limitations in terms of the cross-talk, coupled evolution, instrumental errors and so on.
Thanks to the current advanced pulse techniques, we can reduce these influences and extend this technique to a new stage that the experimental limits can be neglected. In this experiment, we try to use composite pulses to compensate RF field strength variations and frequency offsets.

===[[Optical control of TMDCs valley pseudospin qubits]]===
Quantum dots or single electron transistors, allow for individual control of single charge or spin. In addition, some semiconductor monolayers possess a sizeable direct bandgap of ≈1.5–2 eV in the optical range allowing electrostatic confinement and optical manipulation of carriers. Therefore, we try to adopt the method of this theoretical paper, and see if we can control single qubit or couple 2 qubits optically.

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

===[[Microwave control of superconducting cavity and qubit]]===
This project aims to perform a trial pre-experiment based on the cQED architecture including simulation, calibration, microwave control pulse programming, and so on. The 3D superconducting cavity sample is anchored to the MXC flange inside the Bluefors dilution refrigerator to reach a temperature of around 10mK. On the other hand, the generation of microwave control pulses and the acquisition of output signals are handled by a QM quantum control device, connecting the sample via the control lines and the output lines accordingly. Hence, we can realize several bosonic states via cavity driving and qubit control.

===[[A Nanosecond Pulse Generator based on the Reconfigurable Phase-Locked Loop (PLL) Module in Field Programmable Gate Arrays (FPGAs)]]===
Field Programmable Gate Arrays (FPGAs) are digital integrated circuits (ICs) that contain blocks of logic and interconnects which can be configured and reconfigured even after it is being deployed "in the field". This enables flexible tunability in the function of FPGA-based devices. We seek to replicate the works of Zhu & Wang (2015) to utilise the Phase-Locked Loop (PLL) module in FPGA to implement a nanosecond pulse generator with adjustable frequency and pulse width. Our circuit was designed with Quartus Prime.

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1.2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1.2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1.2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1.2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021||[https://youtu.be/WfP5mahZrWU Optical modulators, part 2]

|-
| 15.2.2021
|[https://youtu.be/m_F4DOHMNeU Homodyne detection techniques] || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques. These techniques, similar to their radiofrequency counterparts, rely on multiplying field amplitudes.

|-
| 1.3.2021
|[https://youtu.be/YkVlxxucLuA Frequency control of laser systems, part 1]
| rowspan="2" |Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions or solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.
|-
| 2.3.2021
|[https://youtu.be/72aVZwI4BHU Frequency control of laser systems, part 2]

|-
| 8.3.2021
|[https://youtu.be/jolUa_EGZEs Interface to computers]
| High level interfacing between computers and electronic hardware: Standard device languages; some serial protocols, some aspects of microcontrollers and FPGAs

|-
| 15.3.2021
|[https://youtu.be/1S0EAnooQMc Pulses in quantum control]
| Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. This covers how they are used, and present a few techniques to generate such control pulses

|-
| 22.3.2021
|[https://youtu.be/PHx-da7RLE8 High voltage techniques]
| Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in LaTeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>
* Should you miss any module or functionality of this wiki, please contact me (Christian Kurtsiefer).

Main Page

2021-03-25T01:22:09Z

Chris: /* Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well) */

Project wiki for the Module QT5201U (Quantum control technology) - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
===[[Wavemeter based on interferometer]]===
Basically we are now trying to build a wavemeter which can measure wavelength from 1200nm to 1800nm because the measurement tool for these lasers is not available now in our lab. It is based on Michelson interferometer.
===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Control over the atomic spins within certain molecules by NMR technique]]===
NMR has been the workhorse for the experimental implementation of quantum protocols, allowing exquisite control of systems up to seven qubits in size. However, there exists some experimental limitations in terms of the cross-talk, coupled evolution, instrumental errors and so on.
Thanks to the current advanced pulse techniques, we can reduce these influences and extend this technique to a new stage that the experimental limits can be neglected. In this experiment, we try to use composite pulses to compensate RF field strength variations and frequency offsets.

===[[Optical control of TMDCs valley pseudospin qubits]]===
Quantum dots or single electron transistors, allow for individual control of single charge or spin. In addition, some semiconductor monolayers possess a sizeable direct bandgap of ≈1.5–2 eV in the optical range allowing electrostatic confinement and optical manipulation of carriers. Therefore, we try to adopt the method of this theoretical paper, and see if we can control single qubit or couple 2 qubits optically.

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

===[[Microwave control of superconducting cavity and qubit]]===
This project aims to perform a trial pre-experiment based on the cQED architecture including simulation, calibration, microwave control pulse programming, and so on. The 3D superconducting cavity sample is anchored to the MXC flange inside the Bluefors dilution refrigerator to reach a temperature of around 10mK. On the other hand, the generation of microwave control pulses and the acquisition of output signals are handled by a QM quantum control device, connecting the sample via the control lines and the output lines accordingly. Hence, we can realize several bosonic states via cavity driving and qubit control.

===[[A Nanosecond Pulse Generator based on the Reconfigurable Phase-Locked Loop (PLL) Module in Field Programmable Gate Arrays (FPGAs)]]===
Field Programmable Gate Arrays (FPGAs) are digital integrated circuits (ICs) that contain blocks of logic and interconnects which can be configured and reconfigured even after it is being deployed "in the field". This enables flexible tunability in the function of FPGA-based devices. We seek to replicate the works of Zhu & Wang (2015) to utilise the Phase-Locked Loop (PLL) module in FPGA to implement a nanosecond pulse generator with adjustable frequency and pulse width. Our circuit was designed with Quartus Prime.

===[[Laminar Air Flow-Based Acusto-Optical Modulator]]===
'''Not an active project! Just a random idea, might be fun to try.''' As discussed during the AOM lecture, a media with a slow speed of sound is preferred for construction of AOMs. The most common material through which the speed of sound is very very slow would be air. Unfortunately, atmospheric air by itself is very chaotic and is not optimal for use in the context of an AOM. Given these considerations, is it possible for a small chamber of a laminar flow of air, modulated by some acoustic frequency, act as an effective AOM?

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1.2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1.2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1.2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1.2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021||[https://youtu.be/WfP5mahZrWU Optical modulators, part 2]

|-
| 15.2.2021
|[https://youtu.be/m_F4DOHMNeU Homodyne detection techniques] || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques. These techniques, similar to their radiofrequency counterparts, rely on multiplying field amplitudes.

|-
| 1.3.2021
|[https://youtu.be/YkVlxxucLuA Frequency control of laser systems, part 1]
| rowspan="2" |Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions or solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.
|-
| 2.3.2021
|[https://youtu.be/72aVZwI4BHU Frequency control of laser systems, part 2]

|-
| 8.3.2021
|[https://youtu.be/jolUa_EGZEs Interface to computers]
| High level interfacing between computers and electronic hardware: Standard device languages; some serial protocols, some aspects of microcontrollers and FPGAs

|-
| 15.3.2021
|[https://youtu.be/1S0EAnooQMc Pulses in quantum control]
| Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. This covers how they are used, and present a few techniques to generate such control pulses

|-
| 22.3.2021
|[https://youtu.be/PHx-da7RLE8 High voltage techniques]
| Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in LaTeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>
* Should you miss any module or functionality of this wiki, please contact me (Christian Kurtsiefer).

Main Page

2021-03-16T05:43:20Z

Chris: /* Project proposals */

Project wiki for the Module QT5201U (Quantum control technology) - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
===[[Wavemeter based on interferometer]]===
Basically we are now trying to build a wavemeter which can measure wavelength from 1200nm to 1800nm because the measurement tool for these lasers is not available now in our lab. It is based on Michelson interferometer.
===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Control over the atomic spins within certain molecules by NMR technique]]===
NMR has been the workhorse for the experimental implementation of quantum protocols, allowing exquisite control of systems up to seven qubits in size. However, there exists some experimental limitations in terms of the cross-talk, coupled evolution, instrumental errors and so on.
Thanks to the current advanced pulse techniques, we can reduce these influences and extend this technique to a new stage that the experimental limits can be neglected. In this experiment, we try to use composite pulses to compensate RF field strength variations and frequency offsets.

===[[Optical control of qubits built on quantum simulator]]===
Quantum dots or single electron transistors, allow for individual control of single charge or spin. In addition, some semiconductor monolayers possess a sizeable direct bandgap of ≈1.5–2 eV in the optical range allowing electrostatic confinement and optical manipulation of carriers. Therefore, we try to adopt the method of this theoretical paper, and see if we can control single qubit or couple 2 qubits optically.

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

===[[Microwave control of superconducting cavity and qubit]]===
This project aims to perform a trial pre-experiment based on the cQED architecture including simulation, calibration, microwave control pulse programming, and so on. The 3D superconducting cavity sample is anchored to the MXC flange inside the Bluefors dilution refrigerator to reach a temperature of around 10mK. On the other hand, the generation of microwave control pulses and the acquisition of output signals are handled by a QM quantum control device, connecting the sample via the control lines and the output lines accordingly. Hence, we can realize several bosonic states via cavity driving and qubit control.

===[[Laminar Air Flow-Based Acusto-Optical Modulator]]===
'''Not an active project! Just a random idea, might be fun to try.''' As discussed during the AOM lecture, a media with a slow speed of sound is preferred for construction of AOMs. The most common material through which the speed of sound is very very slow would be air. Unfortunately, atmospheric air by itself is very chaotic and is not optimal for use in the context of an AOM. Given these considerations, is it possible for a small chamber of a laminar flow of air, modulated by some acoustic frequency, act as an effective AOM?

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1.2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1.2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1.2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1.2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021||[https://youtu.be/WfP5mahZrWU Optical modulators, part 2]

|-
| 15.2.2021
|[https://youtu.be/m_F4DOHMNeU Homodyne detection techniques] || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques. These techniques, similar to their radiofrequency counterparts, rely on multiplying field amplitudes.

|-
| 1.3.2021
|[https://youtu.be/YkVlxxucLuA Frequency control of laser systems, part 1]
| rowspan="2" |Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions or solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.
|-
| 2.3.2021
|[https://youtu.be/72aVZwI4BHU Frequency control of laser systems, part 2]

|-
| 8.3.2021
|[https://youtu.be/jolUa_EGZEs Interface to computers]
| High level interfacing between computers and electronic hardware: Standard device languages; some serial protocols, some aspects of microcontrollers and FPGAs

|-
| 15.3.2021
|[https://youtu.be/1S0EAnooQMc Pulses in quantum control]
| Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. This covers how they are used, and present a few techniques to generate such control pulses

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|-
| ||High voltage techniques || Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in LaTeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>
* Should you miss any module or functionality of this wiki, please contact me (Christian Kurtsiefer).

Main Page

2021-03-16T05:35:13Z

Chris: /* Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well) */

Project wiki for the Module QT5201U (Quantum control technology) - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
Here, links/short descriptions to projects should be listed.
===[[Example project]]===
This is just a dummy project.
===[[Wavemeter based on interferometer]]===
Basically we are now trying to build a wavemeter which can measure wavelength from 1200nm to 1800nm because the measurement tool for these lasers is not available now in our lab. It is based on Michelson interferometer.
===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Control over the atomic spins within certain molecules by NMR technique]]===
NMR has been the workhorse for the experimental implementation of quantum protocols, allowing exquisite control of systems up to seven qubits in size. However, there exists some experimental limitations in terms of the cross-talk, coupled evolution, instrumental errors and so on.
Thanks to the current advanced pulse techniques, we can reduce these influences and extend this technique to a new stage that the experimental limits can be neglected. In this experiment, we try to use composite pulses to compensate RF field strength variations and frequency offsets.

===[[Optical control of qubits built on quantum simulator]]===
Quantum dots or single electron transistors, allow for individual control of single charge or spin. In addition, some semiconductor monolayers possess a sizeable direct bandgap of ≈1.5–2 eV in the optical range allowing electrostatic confinement and optical manipulation of carriers. Therefore, we try to adopt the method of this theoretical paper, and see if we can control single qubit or couple 2 qubits optically.

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

===[[Microwave control of superconducting cavity and qubit]]===
This project aims to perform a trial pre-experiment based on the cQED architecture including simulation, calibration, microwave control pulse programming, and so on. The 3D superconducting cavity sample is anchored to the MXC flange inside the Bluefors dilution refrigerator to reach a temperature of around 10mK. On the other hand, the generation of microwave control pulses and the acquisition of output signals are handled by a QM quantum control device, connecting the sample via the control lines and the output lines accordingly. Hence, we can realize several bosonic states via cavity driving and qubit control.

===[[Laminar Air Flow-Based Acusto-Optical Modulator]]===
'''Not an active project! Just a random idea, might be fun to try.''' As discussed during the AOM lecture, a media with a slow speed of sound is preferred for construction of AOMs. The most common material through which the speed of sound is very very slow would be air. Unfortunately, atmospheric air by itself is very chaotic and is not optimal for use in the context of an AOM. Given these considerations, is it possible for a small chamber of a laminar flow of air, modulated by some acoustic frequency, act as an effective AOM?

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1.2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1.2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1.2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1.2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021||[https://youtu.be/WfP5mahZrWU Optical modulators, part 2]

|-
| 15.2.2021
|[https://youtu.be/m_F4DOHMNeU Homodyne detection techniques] || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques. These techniques, similar to their radiofrequency counterparts, rely on multiplying field amplitudes.

|-
| 1.3.2021
|[https://youtu.be/YkVlxxucLuA Frequency control of laser systems, part 1]
| rowspan="2" |Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions or solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.
|-
| 2.3.2021
|[https://youtu.be/72aVZwI4BHU Frequency control of laser systems, part 2]

|-
| 8.3.2021
|[https://youtu.be/jolUa_EGZEs Interface to computers]
| High level interfacing between computers and electronic hardware: Standard device languages; some serial protocols, some aspects of microcontrollers and FPGAs

|-
| 15.3.2021
|[https://youtu.be/1S0EAnooQMc Pulses in quantum control]
| Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. This covers how they are used, and present a few techniques to generate such control pulses

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|-
| ||High voltage techniques || Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in LaTeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>
* Should you miss any module or functionality of this wiki, please contact me (Christian Kurtsiefer).

Main Page

2021-03-09T01:39:32Z

Chris: /* Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well) */

Project wiki for the Module QT5201U (Quantum control technology) - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
Here, links/short descriptions to projects should be listed.
===[[Example project]]===
This is just a dummy project.
===[[Wavemeter based on interferometer]]===
Basically we are now trying to build a wavemeter which can measure wavelength from 1200nm to 1800nm because the measurement tool for these lasers is not available now in our lab. It is based on Michelson interferometer.
===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Control over the atomic spins within certain molecules by NMR technique]]===
NMR has been the workhorse for the experimental implementation of quantum protocols, allowing exquisite control of systems up to seven qubits in size. However, there exists some experimental limitations in terms of the cross-talk, coupled evolution, instrumental errors and so on.
Thanks to the current advanced pulse techniques, we can reduce these influences and extend this technique to a new stage that the experimental limits can be neglected. In this experiment, we try to use composite pulses to compensate RF field strength variations and frequency offsets.

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

===[[Microwave control of superconducting cavity and qubit]]===
This project aims to perform a trial pre-experiment based on the cQED architecture including simulation, calibration, microwave control pulse programming, and so on. The 3D superconducting cavity sample is anchored to the MXC flange inside the Bluefors dilution refrigerator to reach a temperature of around 10mK. On the other hand, the generation of microwave control pulses and the acquisition of output signals are handled by a QM quantum control device, connecting the sample via the control lines and the output lines accordingly. Hence, we can realize several bosonic states via cavity driving and qubit control.

===[[Laminar Air Flow-Based Acusto-Optical Modulator]]===
'''Not an active project! Just a random idea, might be fun to try.''' As discussed during the AOM lecture, a media with a slow speed of sound is preferred for construction of AOMs. The most common material through which the speed of sound is very very slow would be air. Unfortunately, atmospheric air by itself is very chaotic and is not optimal for use in the context of an AOM. Given these considerations, is it possible for a small chamber of a laminar flow of air, modulated by some acoustic frequency, act as an effective AOM?

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1.2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1.2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1.2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1.2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021||[https://youtu.be/WfP5mahZrWU Optical modulators, part 2]

|-
| 15.2.2021
|[https://youtu.be/m_F4DOHMNeU Homodyne detection techniques] || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques. These techniques, similar to their radiofrequency counterparts, rely on multiplying field amplitudes.

|-
| 1.3.2021
|[https://youtu.be/YkVlxxucLuA Frequency control of laser systems, part 1]
| rowspan="2" |Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions or solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.
|-
| 2.3.2021
|[https://youtu.be/72aVZwI4BHU Frequency control of laser systems, part 2]

|-
| 8.3.2021
|[https://youtu.be/jolUa_EGZEs Interface to computers]
| High level interfacing between computers and electronic hardware: Standard device languages; some serial protocols, some aspects of microcontrollers and FPGAs

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|-
| ||Generating pulse sequences || Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. We present a few techniques to generate such control pulses

|-
| ||High voltage techniques || Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in LaTeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>
* Should you miss any module or functionality of this wiki, please contact me (Christian Kurtsiefer).

Main Page

2021-03-03T05:20:01Z

Chris: /* Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well) */

Project wiki for the Module QT5201U (Quantum control technology) - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
Here, links/short descriptions to projects should be listed.
===[[Example project]]===
This is just a dummy project.
===[[Wavemeter based on interferometer]]===
Basically we are now trying to build a wavemeter which can measure wavelength from 1200nm to 1800nm because the measurement tool for these lasers is not available now in our lab. It is based on Michelson interferometer.
===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Control over the atomic spins within certain molecules by NMR technique]]===
NMR has been the workhorse for the experimental implementation of quantum protocols, allowing exquisite control of systems up to seven qubits in size. However, there exists some experimental limitations in terms of the cross-talk, coupled evolution, instrumental errors and so on.
Thanks to the current advanced pulse techniques, we can reduce these influences and extend this technique to a new stage that the experimental limits can be neglected. In this experiment, we try to use composite pulses to compensate RF field strength variations and frequency offsets.

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

===[[Microwave control of superconducting cavity and qubit]]===
This project aims to perform a trial pre-experiment based on the cQED architecture including simulation, calibration, microwave control pulse programming, and so on. The 3D superconducting cavity sample is anchored to the MXC flange inside the Bluefors dilution refrigerator to reach a temperature of around 10mK. On the other hand, the generation of microwave control pulses and the acquisition of output signals are handled by a QM quantum control device, connecting the sample via the control lines and the output lines accordingly. Hence, we can realize several bosonic states via cavity driving and qubit control.

===[[Laminar Air Flow-Based Acusto-Optical Modulator]]===
'''Not an active project! Just a random idea, might be fun to try.''' As discussed during the AOM lecture, a media with a slow speed of sound is preferred for construction of AOMs. The most common material through which the speed of sound is very very slow would be air. Unfortunately, atmospheric air by itself is very chaotic and is not optimal for use in the context of an AOM. Given these considerations, is it possible for a small chamber of a laminar flow of air, modulated by some acoustic frequency, act as an effective AOM?

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1.2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1.2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1.2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1.2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021||[https://youtu.be/WfP5mahZrWU Optical modulators, part 2]

|-
| 15.2.2021
|[https://youtu.be/m_F4DOHMNeU Homodyne detection techniques] || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques. These techniques, similar to their radiofrequency counterparts, rely on multiplying field amplitudes.

|-
| 1.3.2021
|[https://youtu.be/YkVlxxucLuA Frequency control of laser systems, part 1]
| rowspan="2" |Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions or solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.
|-
| 2.3.2021
|[https://youtu.be/72aVZwI4BHU Frequency control of laser systems, part 2]

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|-
| ||Generating pulse sequences || Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. We present a few techniques to generate such control pulses

|-
| ||Interface to computers || High level interfacing between computers and electronic hardware: Simple python scripting, standard device languages

|-
| ||High voltage techniques || Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in LaTeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>
* Should you miss any module or functionality of this wiki, please contact me (Christian Kurtsiefer).

Main Page

2021-03-03T05:13:18Z

Chris:

Project wiki for the Module QT5201U (Quantum control technology) - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
Here, links/short descriptions to projects should be listed.
===[[Example project]]===
This is just a dummy project.
===[[Wavemeter based on interferometer]]===
Basically we are now trying to build a wavemeter which can measure wavelength from 1200nm to 1800nm because the measurement tool for these lasers is not available now in our lab. It is based on Michelson interferometer.
===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Control over the atomic spins within certain molecules by NMR technique]]===
NMR has been the workhorse for the experimental implementation of quantum protocols, allowing exquisite control of systems up to seven qubits in size. However, there exists some experimental limitations in terms of the cross-talk, coupled evolution, instrumental errors and so on.
Thanks to the current advanced pulse techniques, we can reduce these influences and extend this technique to a new stage that the experimental limits can be neglected. In this experiment, we try to use composite pulses to compensate RF field strength variations and frequency offsets.

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

===[[Microwave control of superconducting cavity and qubit]]===
This project aims to perform a trial pre-experiment based on the cQED architecture including simulation, calibration, microwave control pulse programming, and so on. The 3D superconducting cavity sample is anchored to the MXC flange inside the Bluefors dilution refrigerator to reach a temperature of around 10mK. On the other hand, the generation of microwave control pulses and the acquisition of output signals are handled by a QM quantum control device, connecting the sample via the control lines and the output lines accordingly. Hence, we can realize several bosonic states via cavity driving and qubit control.

===[[Laminar Air Flow-Based Acusto-Optical Modulator]]===
'''Not an active project! Just a random idea, might be fun to try.''' As discussed during the AOM lecture, a media with a slow speed of sound is preferred for construction of AOMs. The most common material through which the speed of sound is very very slow would be air. Unfortunately, atmospheric air by itself is very chaotic and is not optimal for use in the context of an AOM. Given these considerations, is it possible for a small chamber of a laminar flow of air, modulated by some acoustic frequency, act as an effective AOM?

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1.2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1.2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1.2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1.2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021||[https://youtu.be/WfP5mahZrWU Optical modulators, part 2]

|-
| 15.2.2021
|[https://youtu.be/m_F4DOHMNeU Homodyne detection techniques] || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques. These techniques, similar to their radiofrequency counterparts, rely on multiplying field amplitudes.

|-
| 1.3.2021
|[https://youtu.be/YkVlxxucLuA Frequency control of laser systems, part 1]
| rowspan="2" |Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions or solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.
|-
| 2.3.2021
|Frequency control of laser systems, part 2

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|-
| ||Generating pulse sequences || Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. We present a few techniques to generate such control pulses

|-
| ||Interface to computers || High level interfacing between computers and electronic hardware: Simple python scripting, standard device languages

|-
| ||High voltage techniques || Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in LaTeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>
* Should you miss any module or functionality of this wiki, please contact me (Christian Kurtsiefer).

Main Page

2021-03-03T01:43:48Z

Chris: /* Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well) */

Project wiki for the Module QT5201U - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
Here, links/short descriptions to projects should be listed.
===[[Example project]]===
This is just a dummy project.
===[[Wavemeter based on interferometer]]===
Basically we are now trying to build a wavemeter which can measure wavelength from 1200nm to 1800nm because the measurement tool for these lasers is not available now in our lab. It is based on Michelson interferometer.
===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Control over the atomic spins within certain molecules by NMR technique]]===
NMR has been the workhorse for the experimental implementation of quantum protocols, allowing exquisite control of systems up to seven qubits in size. However, there exists some experimental limitations in terms of the cross-talk, coupled evolution, instrumental errors and so on.
Thanks to the current advanced pulse techniques, we can reduce these influences and extend this technique to a new stage that the experimental limits can be neglected. In this experiment, we try to use composite pulses to compensate RF field strength variations and frequency offsets.

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

===[[Microwave control of superconducting cavity and qubit]]===
This project aims to perform a trial pre-experiment based on the cQED architecture including simulation, calibration, microwave control pulse programming, and so on. The 3D superconducting cavity sample is anchored to the MXC flange inside the Bluefors dilution refrigerator to reach a temperature of around 10mK. On the other hand, the generation of microwave control pulses and the acquisition of output signals are handled by a QM quantum control device, connecting the sample via the control lines and the output lines accordingly. Hence, we can realize several bosonic states via cavity driving and qubit control.

===[[Laminar Air Flow-Based Acusto-Optical Modulator]]===
'''Not an active project! Just a random idea, might be fun to try.''' As discussed during the AOM lecture, a media with a slow speed of sound is preferred for construction of AOMs. The most common material through which the speed of sound is very very slow would be air. Unfortunately, atmospheric air by itself is very chaotic and is not optimal for use in the context of an AOM. Given these considerations, is it possible for a small chamber of a laminar flow of air, modulated by some acoustic frequency, act as an effective AOM?

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1.2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1.2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1.2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1.2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021||[https://youtu.be/WfP5mahZrWU Optical modulators, part 2]

|-
| 15.2.2021
|[https://youtu.be/m_F4DOHMNeU Homodyne detection techniques] || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques. These techniques, similar to their radiofrequency counterparts, rely on multiplying field amplitudes.

|-
| 1.3.2021
|[https://youtu.be/YkVlxxucLuA Frequency control of laser systems, part 1]
| rowspan="2" |Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions or solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.
|-
| 2.3.2021
|Frequency control of laser systems, part 2

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|-
| ||Generating pulse sequences || Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. We present a few techniques to generate such control pulses

|-
| ||Interface to computers || High level interfacing between computers and electronic hardware: Simple python scripting, standard device languages

|-
| ||High voltage techniques || Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in LaTeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>
* Should you miss any module or functionality of this wiki, please contact me (Christian Kurtsiefer).

Main Page

2021-02-16T02:02:38Z

Chris: /* Getting started */

Project wiki for the Module QT5201U - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
Here, links/short descriptions to projects should be listed.
===[[Example project]]===
This is just a dummy project.
===[[Wavemeter based on interferometer]]===
Basically we are now trying to build a wavemeter which can measure wavelength from 1200nm to 1800nm because the measurement tool for these lasers is not available now in our lab. It is based on Michelson interferometer.
===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Control over the atomic spins within certain molecules by NMR technique]]===
NMR has been the workhorse for the experimental implementation of quantum protocols, allowing exquisite control of systems up to seven qubits in size. However, there exists some experimental limitations in terms of the cross-talk, coupled evolution, instrumental errors and so on.
Thanks to the current advanced pulse techniques, we can reduce these influences and extend this technique to a new stage that the experimental limits can be neglected. In this experiment, we try to use composite pulses to compensate RF field strength variations and frequency offsets.

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

===[[Microwave control of superconducting cavity and qubit]]===
This project aims to perform a trial pre-experiment based on the cQED architecture including simulation, calibration, microwave control pulse programming, and so on. The 3D superconducting cavity sample is anchored to the MXC flange inside the Bluefors dilution refrigerator to reach a temperature of around 10mK. On the other hand, the generation of microwave control pulses and the acquisition of output signals are handled by a QM quantum control device, connecting the sample via the control lines and the output lines accordingly. Hence, we can realize several bosonic states via cavity driving and qubit control.

===[[Laminar Air Flow-Based Acusto-Optical Modulator]]===
'''Not an active project! Just a random idea, might be fun to try.''' As discussed during the AOM lecture, a media with a slow speed of sound is preferred for construction of AOMs. The most common material through which the speed of sound is very very slow would be air. Unfortunately, atmospheric air by itself is very chaotic and is not optimal for use in the context of an AOM. Given these considerations, is it possible for a small chamber of a laminar flow of air, modulated by some acoustic frequency, act as an effective AOM?

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1.2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1.2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1.2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1.2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021||[https://youtu.be/WfP5mahZrWU Optical modulators, part 2]

|-
| 15.2.2021
|[https://youtu.be/m_F4DOHMNeU Homodyne detection techniques] || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques. These techniques, similar to their radiofrequency counterparts, rely on multiplying field amplitudes.

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|-
| ||Frequency control of laser systems || Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions of solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.

|-
| ||Generating pulse sequences || Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. We present a few techniques to generate such control pulses

|-
| ||Interface to computers || High level interfacing between computers and electronic hardware: Simple python scripting, standard device languages

|-
| ||High voltage techniques || Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in LaTeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>
* Should you miss any module or functionality of this wiki, please contact me (Christian Kurtsiefer).

Main Page

2021-02-16T01:59:25Z

Chris: /* Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well) */

Project wiki for the Module QT5201U - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
Here, links/short descriptions to projects should be listed.
===[[Example project]]===
This is just a dummy project.
===[[Wavemeter based on interferometer]]===
Basically we are now trying to build a wavemeter which can measure wavelength from 1200nm to 1800nm because the measurement tool for these lasers is not available now in our lab. It is based on Michelson interferometer.
===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Control over the atomic spins within certain molecules by NMR technique]]===
NMR has been the workhorse for the experimental implementation of quantum protocols, allowing exquisite control of systems up to seven qubits in size. However, there exists some experimental limitations in terms of the cross-talk, coupled evolution, instrumental errors and so on.
Thanks to the current advanced pulse techniques, we can reduce these influences and extend this technique to a new stage that the experimental limits can be neglected. In this experiment, we try to use composite pulses to compensate RF field strength variations and frequency offsets.

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

===[[Microwave control of superconducting cavity and qubit]]===
This project aims to perform a trial pre-experiment based on the cQED architecture including simulation, calibration, microwave control pulse programming, and so on. The 3D superconducting cavity sample is anchored to the MXC flange inside the Bluefors dilution refrigerator to reach a temperature of around 10mK. On the other hand, the generation of microwave control pulses and the acquisition of output signals are handled by a QM quantum control device, connecting the sample via the control lines and the output lines accordingly. Hence, we can realize several bosonic states via cavity driving and qubit control.

===[[Laminar Air Flow-Based Acusto-Optical Modulator]]===
'''Not an active project! Just a random idea, might be fun to try.''' As discussed during the AOM lecture, a media with a slow speed of sound is preferred for construction of AOMs. The most common material through which the speed of sound is very very slow would be air. Unfortunately, atmospheric air by itself is very chaotic and is not optimal for use in the context of an AOM. Given these considerations, is it possible for a small chamber of a laminar flow of air, modulated by some acoustic frequency, act as an effective AOM?

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1.2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1.2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1.2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1.2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021||[https://youtu.be/WfP5mahZrWU Optical modulators, part 2]

|-
| 15.2.2021
|[https://youtu.be/m_F4DOHMNeU Homodyne detection techniques] || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques. These techniques, similar to their radiofrequency counterparts, rely on multiplying field amplitudes.

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|-
| ||Frequency control of laser systems || Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions of solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.

|-
| ||Generating pulse sequences || Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. We present a few techniques to generate such control pulses

|-
| ||Interface to computers || High level interfacing between computers and electronic hardware: Simple python scripting, standard device languages

|-
| ||High voltage techniques || Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in TeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>

Main Page

2021-02-10T03:29:51Z

Chris: /* Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well) */

Project wiki for the Module QT5201U - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
Here, links/short descriptions to projects should be listed.
===[[Example project]]===
This is just a dummy project.
===[[Wavemeter based on interferometer]]===
Basically we are now trying to build a wavemeter which can measure wavelength from 1200nm to 1800nm because the measurement tool for these lasers is not available now in our lab. It is based on Michelson interferometer.
===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Optical Control of Semiconductor Qubits]]===
Quantum dots or single electron transistors, allow for individual control of single charge or spin. In addition, some semiconductor monolayers possess a sizeable direct bandgap of ≈1.5–2 eV in the optical range allowing electrostatic confinement and optical manipulation of carriers. Therefore, we try to adopt the method of this theoretical paper, and see if we can control single qubit or couple 2 qubits optically.
* Paper link (PDF): [https://s3.us-west-2.amazonaws.com/secure.notion-static.com/b4131068-af98-4ff0-993e-d3c2fdd85d37/PhysRevB.93.045313.pdf?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAT73L2G45O3KS52Y5%2F20210126%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20210126T085925Z&X-Amz-Expires=86400&X-Amz-Signature=7d1660e6d0f736d6fc739a2abb2f634b36990c1520ed037f0a92f35bfd025746&X-Amz-SignedHeaders=host&response-content-disposition=filename%20%3D%22Spin-valley%2520qubit%2520in%2520nanostructures%2520of%2520monolayer%2520semiconductors%253A%2520Optical%2520control%2520and%2520hyperfine%2520interaction.pdf%22 📑]
* Paper link (Original): [https://journals.aps.org/prb/abstract/10.1103/PhysRevB.93.045313 📑], [[Media:PhysRevB.93.045313.pdf|local copy here]]

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

===[[Laminar Air Flow-Based Acusto-Optical Modulator]]===
'''Not an active project! Just a random idea, might be fun to try.''' As discussed during the AOM lecture, a media with a slow speed of sound is preferred for construction of AOMs. The most common material through which the speed of sound is very very slow would be air. Unfortunately, atmospheric air by itself is very chaotic and is not optimal for use in the context of an AOM. Given these considerations, is it possible for a small chamber of a laminar flow of air, modulated by some acoustic frequency, act as an effective AOM?

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1. 2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1. 2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1. 2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1. 2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021||[https://youtu.be/WfP5mahZrWU Optical modulators, part 2]

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|-
| ||Frequency control of laser systems || Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions of solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.

|-
| ||Homodyne detection techniques || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques.

|-
| ||Generating pulse sequences || Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. We present a few techniques to generate such control pulses

|-
| ||Interface to computers || High level interfacing between computers and electronic hardware: Simple python scripting, standard device languages

|-
| ||High voltage techniques || Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in TeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>

Main Page

2021-02-09T05:29:20Z

Chris: /* Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well) */

Project wiki for the Module QT5201U - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
Here, links/short descriptions to projects should be listed.
===[[Example project]]===
This is just a dummy project.
===[[Wavemeter based on interferometer]]===
Basically we are now trying to build a wavemeter which can measure wavelength from 1200nm to 1800nm because the measurement tool for these lasers is not available now in our lab. It is based on Michelson interferometer.
===[[Coincidence Time Measurement of Pulsed Lasers & "Useful" Applications]]===
Proof-of-concept experiment to show how one may use commonly-available materials to measure difference in laser path lengths to sub-millimeter precision with a copper target (TBC). This experiment is done using a 355nm, 120 MHz, 10ps pulsed laser. Upon showing that such a measurement is possible, we shall go on to explore some for-fun applications of this "technology" and see how far and precise we can get.

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Optical Control of Semiconductor Qubits]]===
Quantum dots or single electron transistors, allow for individual control of single charge or spin. In addition, some semiconductor monolayers possess a sizeable direct bandgap of ≈1.5–2 eV in the optical range allowing electrostatic confinement and optical manipulation of carriers. Therefore, we try to adopt the method of this theoretical paper, and see if we can control single qubit or couple 2 qubits optically.
* Paper link (PDF): [https://s3.us-west-2.amazonaws.com/secure.notion-static.com/b4131068-af98-4ff0-993e-d3c2fdd85d37/PhysRevB.93.045313.pdf?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAT73L2G45O3KS52Y5%2F20210126%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20210126T085925Z&X-Amz-Expires=86400&X-Amz-Signature=7d1660e6d0f736d6fc739a2abb2f634b36990c1520ed037f0a92f35bfd025746&X-Amz-SignedHeaders=host&response-content-disposition=filename%20%3D%22Spin-valley%2520qubit%2520in%2520nanostructures%2520of%2520monolayer%2520semiconductors%253A%2520Optical%2520control%2520and%2520hyperfine%2520interaction.pdf%22 📑]
* Paper link (Original): [https://journals.aps.org/prb/abstract/10.1103/PhysRevB.93.045313 📑], [[Media:PhysRevB.93.045313.pdf|local copy here]]

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1. 2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1. 2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1. 2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1. 2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| 8.2.2021||[https://youtu.be/xblN-KzMz0Y Optical modulators, part 1]
| rowspan = "2" | Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.
|-
| 9.2.2021|| Optical modulators, part 2

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|-
| ||Frequency control of laser systems || Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions of solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.

|-
| ||Homodyne detection techniques || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques.

|-
| ||Generating pulse sequences || Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. We present a few techniques to generate such control pulses

|-
| ||Interface to computers || High level interfacing between computers and electronic hardware: Simple python scripting, standard device languages

|-
| ||High voltage techniques || Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in TeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>

Main Page

2021-02-02T05:15:41Z

Chris: /* Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well) */

Project wiki for the Module QT5201U - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
Here, links/short descriptions to projects should be listed.
===[[Example project]]===
This is just a dummy project.
===[[Pulsed laser inteferometry]]===
Interferometry between pulsed Raman beams driving qubit transition in Ytterbium 171+ ions

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Optical Control of Semiconductor Qubits]]===
Quantum dots or single electron transistors, allow for individual control of single charge or spin. In addition, some semiconductor monolayers possess a sizeable direct bandgap of ≈1.5–2 eV in the optical range allowing electrostatic confinement and optical manipulation of carriers. Therefore, we try to adopt the method of this theoretical paper, and see if we can control single qubit or couple 2 qubits optically.
* Paper link (PDF): [https://s3.us-west-2.amazonaws.com/secure.notion-static.com/b4131068-af98-4ff0-993e-d3c2fdd85d37/PhysRevB.93.045313.pdf?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAT73L2G45O3KS52Y5%2F20210126%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20210126T085925Z&X-Amz-Expires=86400&X-Amz-Signature=7d1660e6d0f736d6fc739a2abb2f634b36990c1520ed037f0a92f35bfd025746&X-Amz-SignedHeaders=host&response-content-disposition=filename%20%3D%22Spin-valley%2520qubit%2520in%2520nanostructures%2520of%2520monolayer%2520semiconductors%253A%2520Optical%2520control%2520and%2520hyperfine%2520interaction.pdf%22 📑]
* Paper link (Original): [https://journals.aps.org/prb/abstract/10.1103/PhysRevB.93.045313 📑], [[Media:PhysRevB.93.045313.pdf|local copy here]]

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1. 2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1. 2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1. 2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1. 2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| 1.2.2021||[https://youtu.be/h2LeznCpPTk Optical fiber technology] || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|-
| ||Frequency control of laser systems || Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions of solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.

|-
| ||Homodyne detection techniques || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques.

|-
| ||Generating pulse sequences || Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. We present a few techniques to generate such control pulses

|-
| ||Interface to computers || High level interfacing between computers and electronic hardware: Simple python scripting, standard device languages

|-
| ||High voltage techniques || Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|-
| ||Electro-optics, Accousto-optics, liquid crystals || Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in TeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>

Main Page

2021-02-01T06:48:43Z

Chris: /* Optical Control of Semiconductor Qubits */

Project wiki for the Module QT5201U - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
Here, links/short descriptions to projects should be listed.
===[[Example project]]===
This is just a dummy project.
===[[Pulsed laser inteferometry]]===
Interferometry between pulsed Raman beams driving qubit transition in Ytterbium 171+ ions

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Optical Control of Semiconductor Qubits]]===
Quantum dots or single electron transistors, allow for individual control of single charge or spin. In addition, some semiconductor monolayers possess a sizeable direct bandgap of ≈1.5–2 eV in the optical range allowing electrostatic confinement and optical manipulation of carriers. Therefore, we try to adopt the method of this theoretical paper, and see if we can control single qubit or couple 2 qubits optically.
* Paper link (PDF): [https://s3.us-west-2.amazonaws.com/secure.notion-static.com/b4131068-af98-4ff0-993e-d3c2fdd85d37/PhysRevB.93.045313.pdf?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAT73L2G45O3KS52Y5%2F20210126%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20210126T085925Z&X-Amz-Expires=86400&X-Amz-Signature=7d1660e6d0f736d6fc739a2abb2f634b36990c1520ed037f0a92f35bfd025746&X-Amz-SignedHeaders=host&response-content-disposition=filename%20%3D%22Spin-valley%2520qubit%2520in%2520nanostructures%2520of%2520monolayer%2520semiconductors%253A%2520Optical%2520control%2520and%2520hyperfine%2520interaction.pdf%22 📑]
* Paper link (Original): [https://journals.aps.org/prb/abstract/10.1103/PhysRevB.93.045313 📑], [[Media:PhysRevB.93.045313.pdf|local copy here]]

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1. 2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1. 2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1. 2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1. 2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| ||Optical fiber technology || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|-
| ||Frequency control of laser systems || Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions of solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.

|-
| ||Homodyne detection techniques || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques.

|-
| ||Generating pulse sequences || Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. We present a few techniques to generate such control pulses

|-
| ||Interface to computers || High level interfacing between computers and electronic hardware: Simple python scripting, standard device languages

|-
| ||High voltage techniques || Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|-
| ||Electro-optics, Accousto-optics, liquid crystals || Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in TeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>

File:PhysRevB.93.045313.pdf

2021-02-01T06:47:23Z

Chris:

Main Page

2021-01-27T03:50:10Z

Chris: /* Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well) */

Project wiki for the Module QT5201U - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually. If you have not yet created an account, do let me know - Christian.

==Project proposals==
Here, links/short descriptions to projects should be listed.
===[[Example project]]===
This is just a dummy project.
===[[Pulsed laser inteferometry]]===
Interferometry between pulsed Raman beams driving qubit transition in Ytterbium 171+ ions

===[[Saturated Absorption Spectroscopy + Frequency Modulation Locking on the D2 line of Rubidium 87]]===
With a combination of the Saturation Spectroscopy and Frequency Modulation techniques, we aim at stabilizing the wavelength of a Diode Laser at approximately 780.241 nm which corresponds to the transition <math>5S_{1/2} \rightarrow 5P_{3/2}</math> (also known as D2 line) of Rubidium 87. Additionally we will implement in the experiment a Red Pitaya, which is a minicomputer capable of replacing things like an Oscilloscope, Function Generator and PID controller. Therefore reducing the space needed for the experiment.

===[[Optical Control of Semiconductor Qubits]]===
Quantum dots or single electron transistors, allow for individual control of single charge or spin. In addition, some semiconductor monolayers possess a sizeable direct bandgap of ≈1.5–2 eV in the optical range allowing electrostatic confinement and optical manipulation of carriers. Therefore, we try to adopt the method of this theoretical paper, and see if we can control single qubit or couple 2 qubits optically.
* Paper link (PDF): [https://s3.us-west-2.amazonaws.com/secure.notion-static.com/b4131068-af98-4ff0-993e-d3c2fdd85d37/PhysRevB.93.045313.pdf?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAT73L2G45O3KS52Y5%2F20210126%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20210126T085925Z&X-Amz-Expires=86400&X-Amz-Signature=7d1660e6d0f736d6fc739a2abb2f634b36990c1520ed037f0a92f35bfd025746&X-Amz-SignedHeaders=host&response-content-disposition=filename%20%3D%22Spin-valley%2520qubit%2520in%2520nanostructures%2520of%2520monolayer%2520semiconductors%253A%2520Optical%2520control%2520and%2520hyperfine%2520interaction.pdf%22 📑]
* Paper link (Original): [https://journals.aps.org/prb/abstract/10.1103/PhysRevB.93.045313 📑]

===[[A temperature-tunable etalon for optical telecommunication wavelength]]===
This project aims to build a Fabry-perot interferometer (also called Etalon) that works at the optical telecommunication wavelengths (1260nm-1625nm). This depicted etalon is made out of a single piece of polished silicon wafer with a thickness of about 100μm. The free spectral range (FSR) of the etalon can be adjusted by changing its thickness through temperature tuning. We will also explore the possibility of applying highly reflective (HR) coatings to the silicon wafer to achieve a high cavity finesse and a narrow transmission line-width.

==Material requests==
Please add stuff we should organize one way or the other here:
* more space
* cookies...

==Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well)==
Feel free to add topics or aspects to this list. At the moment, this is just a copy of the tentative syllabus:

{| class="wikitable"
!Date !! Topic !! Description

|-
| 18.1. 2021
|[https://youtu.be/vDIOn2SHLJE Paraxial optics, part 1]
| rowspan = "2" | Optical systems often work with Gaussian beams. We cover practical design techniques like the ABCD matrix formalism for simple optical systems.
|-
| 19.1. 2021
|[https://youtu.be/yO3JcuCOVoc Paraxial optics, part 2] (only first part of lecture)
|-
| 25.1. 2021||[https://youtu.be/nNU1eEOaPdY Optical cavities, part 1] || Many optical techniques require to work with optical cavities. We cover how to design them, and how to couple light into very basic devices. This lecture covered some theory basics.
|-
| 26.1. 2021||[https://youtu.be/ekfhUi2JjFM Optical cavities, part 2]|| Some more aspects of optical cavities, and dielectric coatings for mirrors and such

|-
| ||Optical fiber technology || Some properties of optical fibers as the most common optical waveguide are covered, including optical mode spectrum, dispersion and transmission properties.

|-
| ||Practical aspects of superconducting systems || We cover different materials, transition temperatures, temperature measurement techniques and thermal insulation / conduction techniques.

|-
| ||Frequency control of laser systems || Many laser systems in quantum technologies require to have a well-defined frequency relationship with atomic transitions of solid state qubits. We cover typical techniques how laser systems can be controlled to a high enough accuracy, utilizing spectroscopy techniques and control systems.

|-
| ||Homodyne detection techniques || Measurement of optical fields in many continuous variable scenarios require knowledge of optical homodyning and heterodyning techniques.

|-
| ||Generating pulse sequences || Many quantum systems require short control pulses, either in form of optical pulses or radiofrequency pulses. We present a few techniques to generate such control pulses

|-
| ||Interface to computers || High level interfacing between computers and electronic hardware: Simple python scripting, standard device languages

|-
| ||High voltage techniques || Working with high voltages requires a spectrum of techniques that is differing from more conventional electronics. A few aspects (field emission, dielectric strength, specific components) are covered.

|-
| ||Electro-optics, Accousto-optics, liquid crystals || Many optical modulation techniques require rely on devices or materials where optical properties can be changed electrically; we cover accousto-optical and electro-optical devices, as well as liquid crystal systems.

|}

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in TeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>

Main Page

2021-01-26T02:35:14Z

Chris: /* Stuff to be covered in the lecture slots on Mondays (sometimes Tuesdays as well) */

Main Page

2021-01-25T10:49:58Z

Chris: /* Stuff to be covered in the lecture slots on Mondays */

Main Page

2021-01-20T10:50:55Z

Chris: /* Stuff to be covered in the lecture slots on Mondays */

Main Page

2021-01-14T08:09:20Z

Chris:

MZ Interferometer/AOM Imaging/Atomic Spectroscopy (Mu Young & Wen Yi)

2021-01-14T08:08:17Z

Chris: /* Atomic Spectroscopy */

Team Members: Kim Mu Young & Tan Wen Yi

==Mach-Zehnder Interferometer==
Aim: Carry out the MZ Interferometer experiment using a laser source. Observe constructive & destructive interference, and measure phase shift caused by different commonly-used optical elements

==AOM Imaging==
Context: Some experiments require the scanning of AOM frequencies. However, this results in the beam being deflected at slightly different angles. This can become an issue in ion trap systems where beam waists are very small (~10 um) and ion-beam alignment important.

Aim: We propose the use of a composite lens system on a movable platform, controlled by an actuator, so that a beam shift caused by a change in driving AOM frequency is automatically compensated for.

==Atomic Spectroscopy==
Aim: Observing Doppler-free spectrum of an iodine cell.

Material Required: The 739nm at Dzmitry lab is currently semi-available and thus may be used. Still need an iodine cell though. - Comment CK: if 780nm lasers are ok, we have probably many of them around. Will try to source an iodine cell. What line width are you aiming at?

==Comments==

New page with a sensible name

2021-01-12T06:14:19Z

Chris: Created page with "here you are"

here you are

Example project

2021-01-12T06:14:10Z

Chris: /* Method */

This page should aim as the main project page, stating who worked on it, and keeping track of results. Feel free to add additional pages, but make sure they are all linked this page so they can be found.

Also add the team members here. My name...

==Aim / description==
This is to see if referencing works<ref>B.E.A. Saleh, M.C. Teich: Funamentals of Photonics, Wiley Interscience, ISBN 0-471-83965-5</ref>.

==Method==
*<math>a^2=b^2+c^2</math>
* [[new page with a sensible name]]

==Results==

==References==
<references />

Example project

2021-01-12T06:13:08Z

Chris:

This page should aim as the main project page, stating who worked on it, and keeping track of results. Feel free to add additional pages, but make sure they are all linked this page so they can be found.

Also add the team members here. My name...

==Aim / description==
This is to see if referencing works<ref>B.E.A. Saleh, M.C. Teich: Funamentals of Photonics, Wiley Interscience, ISBN 0-471-83965-5</ref>.

==Method==
<math>a^2==b^2+c^2</math>

==Results==

==References==
<references />

Example project

2021-01-12T05:26:23Z

Chris: /* Results */

This page should aim as the main project page, stating who worked on it, and keeping track of results. Feel free to add additional pages, but make sure they are all linked this page so they can be found.

Also add the team members here.

==Aim / description==
This is to see if referencing works<ref>B.E.A. Saleh, M.C. Teich: Funamentals of Photonics, Wiley Interscience, ISBN 0-471-83965-5</ref>.

==Method==

==Results==

==References==
<references />

Example project

2021-01-12T05:25:23Z

Chris: /* Aim / description */

This page should aim as the main project page, stating who worked on it, and keeping track of results. Feel free to add additional pages, but make sure they are all linked this page so they can be found.

Also add the team members here.

==Aim / description==
This is to see if referencing works<ref>B.E.A. Saleh, M.C. Teich: Funamentals of Photonics, Wiley Interscience, ISBN 0-471-83965-5</ref>.

==Method==

==Results==

Example project

2021-01-12T05:11:05Z

Chris: Created page with "This page should aim as the main project page, stating who worked on it, and keeping track of results. Feel free to add additional pages, but make sure they are all linked thi..."

Main Page

2021-01-12T05:07:49Z

Chris:

Main Page

2021-01-11T02:47:43Z

Chris:

Project wiki for the Module QT5201U - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually, as I have not yet figured out how to use the NUS login.

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* Math can be entered in TeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>

Main Page

2021-01-11T02:47:14Z

Chris:

Project wiki for the Module QT5201U - AY20/21S2

Welcome to the wiki project page. This will be the place for documenting projects. To be able to write something to this wiki, we need to create a user login manually, as I have not yet figured out how to use the NUS login.

== Getting started ==
Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* [https://lists.wikimedia.org/mailman/listinfo/mediawiki-announce MediaWiki release mailing list]
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Localisation#Translation_resources Localise MediaWiki for your language]
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:Combating_spam Learn how to combat spam on your wiki]
* Math can be entered in TeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>

Main Page

2021-01-10T06:46:29Z

Chris:

MediaWiki has been installed.

Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.

== Getting started ==
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:Configuration_settings Configuration settings list]
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* [https://lists.wikimedia.org/mailman/listinfo/mediawiki-announce MediaWiki release mailing list]
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Localisation#Translation_resources Localise MediaWiki for your language]
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:Combating_spam Learn how to combat spam on your wiki]
* Math can be entered in TeX style: <code><nowiki><math>r^2=\sqrt{x^2+y^2}</math></nowiki></code> renders as <math>r^2=\sqrt{x^2+y^2}</math>