QUANTUM MANIPULATIONS OF TRAPPED ELECTRONS ON LIQUID HELIUM

Transcription

1 QUANTUM MANIPULATIONS OF TRAPPED ELECTRONS ON LIQUID HELIUM L. F. Wei Quanum Opoelecronics Laboraory QOL, Sowhwes Jiaoong Universiy, Chengdu, China & Sae Key of Opoelecric Maerials and echnolies, Sun Ya-sen Universiy, Guangzhou, China Collaborae wih: M. Zhang, Q. Wei, Y. W. Wang, and X. Shi a SWJTU

2

3 OUTLINE Backgrounds and Inroducion Coheren manipulaions of surface-elecron saes by conrolling heir evoluion-imes Quanum logic gae wih surface-elecron saes by populaion passages Applicaion o quanum devices Conclusions and Discussions

4 BACKGROUNDS AND INTRODUCTION: We are working on Circui QEDs Theory and Exp. Single phoons: generaions and manipulaions Exp. Trapped ions Theory V Trapped elecrons on liquid Helium Theory and fuure Exp. Superconducing Single-phoon deecions Exp.

5 Elecrons rapped on Liquid Helium +Q V Z ε b ε -Q Image poenial

6 Single elecrons on liquid Helium A single elecron is weakly araced and rapped by an image poenial of he form V z = - Λe z,, z z > 1GHz ~ 5K Quanum coheren manipulaion requires very low-emperaure: <1K!

7 Quanum compuaion wih surface-sae elecrons: Plazman-Dykman Model cos, H x z ω σ σ ω = Ω Ω Ω + = h h Single-qubi gaes achieved by precisely conrolling Rabi oscillaions A A i A U x, ] sin[ ] cos[ = Ω + = σ + M. I. Dykman e al., PRB 67,

8 Quanum compuaion wih surface-sae elecrons: Plazman-Dykman Model ξ = C xx 1 P. M. Plazman and M. I. Dykman, Science 84, M. J. Lea e al., Forschr. Phys. 48, 119.

9 BACKGROUNDS AND INTRODUCTION Two kinds of ways-four approaches o quanum compuing QC QC by Adiabaic coninuous evoulaions AQC wihou gaes Farhi e al., Science One - way measuremens Universal gaes GQC geomeric phases finie - ime evoluions Barenco e al., PRA,

10 Evoulion-ime sensiive and insensiive QGs Single-qubi gaes σ x - roaions by usual Rabi oscillaions Pσ x cos ω ω Evoluion-ime sensiive oscillaion successful probabiliy 1 = [1 cos ]/ Our approach: Chirping qubi s level 1 Ω cos ω ω H in 1 = Ω Ω Bidirecional adiabaic populaion ransfers 1 1 σ x 1 : 1

11 Evoulion-ime sensiive and insensiive QGs Two-qubi gaes H Inerbi ineracion ime is usually required o be precisely se for implemening wo-qubi quanum gaes. For example ω K σ + σ σ z + = i i j i= 1, i j T Kd = π Our approach: chirping one qubi s level o impelemen ETIQG. H in ω K z + z H = σ i + σ i σ j + σ i= 1, i j 1 = K K i -SWAP gae: evoluion ime insensiive: i - SWAP gae evoluion ime sensiive :, i 1, 1 i

12 A O B Ω

13 AQC Ground sae of Hi is easily accessible. Ground sae of Hf encodes he soluion o a hard compuaional problem. i f Adiabaically, AQC is evoluion-ime insensiive bu no universal, in principle. GQC Universal compuing Implemened by a series of evoluion-ime sensiive quanum gaes H Z X ψ T ψ Moivaion: Proposes an evoluion-ime insensiive GQC wih EH

14 Evoluion-ime dependen quanum manipulaions Laser induced orbi-orbi couplings of an elecron on he liquid Helium M. Zhang, H. Y. Jia, and L. F. Wei, Phys. Rev. A,

15 Evoluion-ime dependen quanum manipulaions Evoluion-ime sensiive quanum gae wih a single EH Quanum gae wih a single EH could be implemened using he ion-rap echnique: C. Monroe e al, PRL, 75, M. Zhang, H. Y. Jia, and L. F. Wei, Phys. Rev. A,

16 Evoluion-ime dependen quanum manipulaions Quanum manipulaions of EHs by conrollable spin-orbial ineracions Why spins?

17 Evoluion-ime dependen quanum manipulaions Quanum manipulaions of EHs by conrollable spin-orbial ineracions Why spins? Inerspin couplings are implemened by he magneic dipoledipole ineracion beween he spins Alernaively, he elecric dipole-dipole ineracion could also be uilized o realize he spin-spin couplings! --Our moivaion.

18 Evoluion-ime dependen quanum manipulaions Quanum manipulaions of EHs by conrollable spin-orbial ineracions Spin-orbi coupling wih a single rapped elecron

19 Evoluion-ime dependen quanum manipulaions Quanum manipulaions of EHs by conrollable spin-orbial ineracions Spin-orbi JC coupling beween he disan elecrons Large-deuning Orbial Coulomb ineracion: M. Zhang and L. F. Wei, ArXiv: v1, 19 Mar 1

20 Consider he reverse field and he Sark shif field, he Hamilonian of he sysem is Evoluion-ime insensiive quanum manipulaions: adiabaic populaion passages for single-qubi gae ]/ [ 1 sin cos 1 cos sin + Ω ± = = + = ± + µ ϑ ϑ λ ϑ ϑ λ Ω Ω = 1 in H an Ω = θ Liquid helium h z x [ ] << + Ω Ω Ω = d d d d β Adiabaic parameer

21 Numerical simulaions Pulse inensiy 1 5 Sark pusle Pump pusle a Populaion 1.5 > 1> > b β 1 =.13 Pulse inensiy ns c 6 4 Sark pusle Pump pusle 5 5 ns Populaion 5 5 ns 1 d.5 > 1> > 5 5 ns β =.9

22 Two-qubi gae by adiabaic populaion passages In order o implemen he general i-swap gae, we fix he field applied o he firs qubi and change ha applied o he second one, hen he oal Hamilonian is h 1 z d x Liquid helium V1 V

23 Numerical simulaions Energy ev x > 3 1 1> 1 a 1> Populaion b 1> 1> > 1 1 ns..1 β =.1 ns

24 Evoluion-ime insensiive quanum manipulaions: ime-evoluion operaor We consider a wo level sysem described by he Hamilionian H ˆ = A σˆ + z B σˆ x U ˆ = e iα σˆ x e iβ σˆ y e iγ σˆ z The corresponding ime evoluion operaor deermined by α& = A cos[α ]an[β ] B & β = A sin[α ] cos[α ] & γ = A α = β = γ = cos[β ]

25 Single-qubi quanum gae achieved non-adiabaically = e ξ x z dc i z e z z ee H σ ξ σ ˆ ˆ ˆ = = E dc e β 1 =.7

26 Single-qubi quanum gae achieved non-adiabaically The dynamics of he driven wo-qubi sysem can be described by β =.5

27 Applicaion o quanum devices Double-frequency device M. Zhang e al., arxiv:14.966v1

28 Applicaion o quanum devices TGHz radiaion sources ~mm M. Zhang e al., Opics Leers,

29 Fuure Works: wih our experimeal sysems Cryofree diluion refrigeraor: <15mK Wih elecrons on Helium: 1. Quanum devices wih EHs based on single-quanum manipulaions. Invesigae quanum phase ransiions wih EHs.

30 Conclusions and Discussions EHs could be manipulaed coherenly Quanum gaes could be deerminisically implemened by evoulion-ime insensiive populaion passages Quanum manipulaions of EHs could be uilized o design novel quanum devices Readou of single-quanum sae is a challenge for he curren echnique.

31 Thank you and Welcome o Chengdu