超导系统下利用量子非破坏性测量制备量子态  

Using prepare fock state in superconducting system by quantum non-demolition measurement

作　　者：张立言 杨传生 ZHANG Li-yan;YANG Chuan-sheng(Key Laboratory of Quantum Information,University of Science and Technology of China,Hefei 230026,China)

机构地区：[1]中国科学技术大学中国科学院量子信息重点实验室,安徽合肥230026

出　　处：《光电子．激光》2018年第11期1200-1205,共6页Journal of Optoelectronics·Laser

基　　金：国家自然科学基金(11674305 11474271)资助项目

摘　　要：基于超导量子电路系统,我们提出了通过量子非破坏性测量的方法来实现光子的量子态制备。由约瑟夫森结构成的两能级超导量子比特,在与腔耦合的情况下,其能级会产生斯塔克位移,位移的大小与腔内光子数成正比。利用超导量子比特能级位移受到腔内光子影响这一性质,在波导与超导量子比特耦合的情况下,通过波导中光子透过率的测量,从而判断出腔内的光子数。这种测量方式对腔内的光子不产生影响,因而是量子非破坏性测量,进而实现腔内光子的量子态制备。此外,我们还讨论了相关参数对制备效果的影响,在此基础之上,提出了通过反馈重复测量的方法来提高制备效率,从而实现目标量子态的快速制备。Based on the superconducting quantum circuit system, we propose a quantum non-demolition measurement for preparing Fock states. In the case of coupling with the cavity, the two-level supercon- ducting qubit formed by Josephson structure will produce a Stark shift, which is proportional to the num- ber of photons in the cavity. Based on the property that the energy level shift of superconducting quantum bit is affected by the photon in the cavity,the number of photons in the cavity can be determined by the measurement of the photon transmittance in the waveguide when the waveguide is coupled with the su perconducting qubit. This measurement method has no influence on the photons in the cavity, so it is a quantum non-demolition measurement, and then the quantum states of the photons in the cavity can be prepared. In addition,we also discuss the influence of relative parameters on the preparation effect. Based on this,we propose a method of feedback repeated measurement to improve the preparation efficiency and realize the rapid preparation of the target quantum state.

关 键 词：超导量子比特 电路量子电动力学 量子非破坏性测量 FOCK态 

分 类 号：O431.2[机械工程—光学工程]