Coherent electrical rotations of valley states in Si quantum dots using the phase of the valley-orbit coupling

Wu, Yue; Culcer, Dimitrie

doi:10.1103/physrevb.86.035321

Cited by 21 publications

(30 citation statements)

References 110 publications

(129 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the effective mass (EM) approximation the orbital ground state electron wavefunctions of a multi-valley system with valley ξ = z,z residing in quantum dot q = l, c, r is given by [69][70][71][72][73][74][75]…”

Section: Appendix B: Molecular Orbital Analysismentioning

confidence: 99%

“…The remaining factors describe the confinement along z-direction in a quantum well with length d R q , with z-valley position k ξ = ±k 0 in k-space. The electronic quantum dot wavefunction of a multi-valley system in the first excited orbital state can similarly be approximated by [69,70,[74][75][76][77][78][79][80].…”

Section: Appendix B: Molecular Orbital Analysismentioning

confidence: 99%

See 1 more Smart Citation

Quadrupolar Exchange-Only Spin Qubit

2018

View full text Add to dashboard Cite

We propose a quadrupolar exchange-only spin (QUEX) qubit that is highly robust against charge noise and nuclear spin dephasing, the dominant decoherence mechanisms in quantum dots. The qubit consists of four electrons trapped in three quantum dots, and operates in a decoherencefree subspace to mitigate dephasing due to nuclear spins. To reduce sensitivity to charge noise, the qubit can be completely operated at an extended charge noise sweet spot that is first-order insensitive to electrical fluctuations. Due to on-site exchange mediated by the Coulomb interaction, the qubit energy splitting is electrically controllable and can amount to several GHz even in the "off" configuration, making it compatible with conventional microwave cavities. arXiv:1807.10471v1 [cond-mat.mes-hall] 27 Jul 2018 H eff =     J 0,0J0,1J0,2 0

show abstract

Section: Appendix B: Molecular Orbital Analysismentioning

confidence: 99%

Section: Appendix B: Molecular Orbital Analysismentioning

confidence: 99%

Quadrupolar Exchange-Only Spin Qubit

2018

View full text Add to dashboard Cite

show abstract

“…In a recent proposal, Wu et al [33] suggest using only the valley degree of freedom as a qubit and fix the spin degree of freedom by a strong in-plane magnetic field. Also, for Si quantum dots, the possibilities of valley-only qubit manipulation are currently under theoretical investigation [34][35][36].…”

Section: Introductionmentioning

confidence: 99%

Universal quantum computing with spin and valley states

2012

View full text Add to dashboard Cite

We investigate a two-electron double quantum dot with both spin and valley degrees of freedom as they occur in graphene, carbon nanotubes or silicon and regard the 16-dimensional space with one electron per dot as a four-qubit logic space. In the spin-only case, it is well known that the exchange coupling between the dots combined with arbitrary single-qubit operations is sufficient for universal quantum computation. The presence of valley degeneracy in the electronic band structure alters the form of the exchange coupling and, in general, leads to spin-valley entanglement. Here, we show that universal quantum computation can still be performed by exchange interaction and singlequbit gates in the presence of an additional (valley) degree of freedom. We present an explicit pulse sequence for a spin-only controlled-NOT consisting of the generalized exchange coupling and single-electron spin and valley rotations. We also propose state preparations and projective measurements with the use of adiabatic transitions between states with (1,1) and (0,2) charge distributions similar to the spin-only case, but with the additional requirement of controlling the spin and valley Zeeman energies by an external magnetic field. Finally, we demonstrate a universal two-qubit gate between a spin and a valley qubit, allowing universal gate operations on the combined spin and valley quantum register.

show abstract

“…Electrical tunability in the range from 0.3 to 0.8 meV was demonstrated [45]. Calculations show that while arg(V VO ) is only slightly influenced by an applied electric field [61], it depends on the conduction band offset [29]; thus, a structure with an alternating top layer material, e.g., SiO 2 and SiGe or Si 1−x Ge x with a varying x could provide the difference in arg(V VO ), i.e. ϕ = 0, which is needed in our scheme between dots I and II and between III and IV, while arg(V VO ) should be the same in dot II and IV.…”

mentioning

confidence: 98%

Hybrid Spin and Valley Quantum Computing with Singlet-Triplet Qubits

2014

View full text Add to dashboard Cite

The valley degree of freedom in the electronic band structure of silicon, graphene, and other materials is often considered to be an obstacle for quantum computing (QC) based on electron spins in quantum dots. Here we show that control over the valley state opens new possibilities for quantum information processing. Combining qubits encoded in the singlet-triplet subspace of spin and valley states allows for universal QC using a universal two-qubit gate directly provided by the exchange interaction. We show how spin and valley qubits can be separated in order to allow for single-qubit rotations.

show abstract

Coherent electrical rotations of valley states in Si quantum dots using the phase of the valley-orbit coupling

Cited by 21 publications

References 110 publications

Quadrupolar Exchange-Only Spin Qubit

Quadrupolar Exchange-Only Spin Qubit

Universal quantum computing with spin and valley states

Hybrid Spin and Valley Quantum Computing with Singlet-Triplet Qubits

Contact Info

Product

Resources

About