关于多比特电路量子动力学系统中光子自由度的消除方案研究  

On the scheme of cavity photon elimination in multi-qubit circuit-quantum electrodynamics system

作　　者：孟建宇[1] 王培月[1] 冯伟[1] 杨国建[1] 李新奇[1] 

机构地区：[1]北京师范大学物理系,北京100875

出　　处：《物理学报》2012年第24期43-51,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:101202101;10874176);国家科技部973项目(批准号:2011CB808502;2012CB932704)资助的课题~~

摘　　要：基于超导传输线和超导量子比特相互耦合的电路量子电动力学(quantum electrodynamics,QED)系统,是研究固态量子信息和量子测量与控制的理想实验平台.本文在已有工作(单比特电路QED)基础上,进一步研究多比特电路QED系统.具体通过对两比特系统的量子测量和量子控制动力学的模拟,检验了"绝热消除"和"极化子变换"两种消除微腔光子自由度方法的适用条件.和单比特情况不同,我们特别检验了两比特系统Bell纠缠态的"确定性"制备问题.在量子路径水平上模拟发现,由于反馈操作引起量子比特状态翻转,使得极化子变换方法失效,它所导出的"有效测量算符"(其中含有非平庸的"宇称项")此时也将变得没有意义.Solid-state superconducting circuit-quantum electrodynamics （QED） system is a promising candidate for quantum information processing and an ideal platform for quantum measurement and quantum control studies. As an extension to our previous simulation for single qubit circuit-QED, in this work we simulate the quantum measurement and control of multi-qubit system. Particularly, we consider the deterministic generation of a two-qubit Bell state. In this context we examine the validity conditions of two cavity- photon-elimination scheme. On the level of quantum trajectory simulation, we find that, owing to the qubit flip caused by feedback, the advanced polaron-transformation scheme is no longer applicable if the measurement is not weak, which also makes meaningless the elegant effective measurement operator.

关 键 词：电路QED 绝热消除 极化子变换 量子反馈控制 

分 类 号：O413.2[理学—理论物理]