Optical control of TMDCs valley pseudospin qubits

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Description

  • The strategies and materials for building universal quantum computers are being actively researched, and various platforms for holding qubits have been proposed and tested[1][2][3][4][5]. Within all the options such as superconducting qubits and ion trap qubits, solid-state qubits have illustrated great benefits of the compatibility with the existing semiconductor technology, which attracts lots of attention to this platform. Moreover, because of the direct band gap and strong spin-orbit coupling discovered in the monolayer transition metal dichalcogenides (TMDCs), especially 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[6][7], chances are TMDCs materials have the potential to become the promising platform for fabricating qubits. There are four main types of TMDCs that have been suggested as advantageous in acting qubits, WS2 , WSe2 , MoS 2 and MoSe2 . Kormányos et al used DFT calculations to confirm that WS2 and WSe2 , are better than MoS2 and MoSe2 in terms of the spin-valley coupling[8], which is really important since spin-valley coupling is regarded as a key factor that can improve the coherence lifetime of spin-valley states. As a result, as inspired by the idea from the paper[9], we intend to build a quantum simulator and control the spin-valley action within in optically manner.

Q & A

What are K & K' points?

K & K' points
  • K-points are sampling points of Brillouin zone in reciprocal lattice

Choose monolayer TMDCs materials or 2D heterostructure?

  • There are four main carrier properties that optimal Opto-valleytronics should possess.
    1. long carrier lifetime
    2. long valley lifetime
    3. high valley polarization
    4. long valley coherence time
  • By adopting 2D heterostructure TMDCs materials, we can create these conditions for building promising quantum platform. (eg. Due to the type II band alignment and weak hybridization of van der Waals heterostructure, the electron–hole layer separation, the electron–hole exchange interaction is greatly reduced, resulting in a long cryogenic lifetime (ns to μs)and valley lifetime (~ 10 ns) of the interlayer exciton[10])

Method

Principle

Experimental setup

Quantum simulator

  • We intend to use WSe2 2D heterostructure encapsulated in hexagonal boron nitride (h-BN) as the physical platform, and ...

Qubit initialisation

Qubit control

Qubit readout

Results

References

  1. ↑ Experimental perfect state transfer of an entangled photonic qubit[1]
  2. ↑ Superconducting Qubits: Current State of Play[2]
  3. ↑ Two-qubit entangling gates within arbitrarily long chains of trapped ions[3]
  4. ↑ Digital Coherent Control of a Superconducting Qubit[4]
  5. ↑ Fast quantum logic gates with trapped-ion qubits[5]
  6. ↑ Atomically Thin MoS2: A New Direct-Gap Semiconductor[6]
  7. ↑ Emerging Photoluminescence in Monolayer MoS2[7]
  8. ↑ Spin-Orbit Coupling, Quantum Dots, and Qubits in Monolayer Transition Metal Dichalcogenides[8]
  9. ↑ Spin-valley qubit in nanostructures of monolayer semiconductors: Optical control and hyperfine interaction[9]
  10. ↑ Opto-valleytronics in the 2D van der Waals heterostructure[10]
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