时变外磁场下海森堡自旋链的热纠缠  

Thermalentanglement in a Heisenberg spin chain with time-varying external magnetic fields

作　　者：黄利元 HUANG Li-Yuan(School of Information Science and Technology, Xiamen University Tan Kah Kee College, Zhangzhou 363105, China)

机构地区：[1]厦门大学嘉庚学院信息科学与技术学院,漳州363105

出　　处：《原子与分子物理学报》2020年第3期413-419,共7页Journal of Atomic and Molecular Physics

基　　金：国家自然科学基金(11374096)。

摘　　要：研究了时变外磁场下两量子比特海森堡XXZ自旋链的热力学纠缠,得到两个角频率ω1、ω2的余弦时变外磁场分别加在两个量子比特上的纠缠度C的解析表达式,并在此基础上进行数值计算.仔细讨论了时变外磁场的角频率ω1、ω2对纠缠度C的影响,同时,分析了在时变外磁场的影响下,纠缠度C随时间演化的情况.结果表明:选取一定时刻,当ω1和ω2取值为不同的组合时,纠缠度C可以取不同的值.当取值恰当时,系统可以维持在较大的纠缠度上.另外,当ω1=ω2时,C虽然会随时间发生周期性变化,但始终能保持较大的值,这对系统需要较大纠缠是有意义的.而当ω1和ω2为其它的倍数关系时,根据C的变化情况可以用作快速反应开关.这些结论在固态系统中进行量子信息研究也将发挥很大的作用.The thermal entanglement of two-qubit Heisenberg XXZ spin chain with two time-varying external magnetic fields in which the angular frequencies areω1 andω2 respectively is investigated by concurrence measure of entanglement C.The influences of the angular frequenciesω1 andω2 on the concurrence C are studied in detail.Meanwhile,the evolution of the C with time under the time-varying external magnetic fields is also analysed.The results show that by choosing a certain moment,the different values of C can be obtained with different combinations ofω1 andω2.When the combination is appropriate,the system can keep larger values of the thermal entanglement.What’s more,whenω1=ω2,although the C varies periodically with time,it can maintain comparatively high values all the time,which is significant when the system needs higher entanglement.In addition,whenω1 is other times asω2,it can be used for fast reaction switch according to the change of the C.These conclusions will be useful in the research of quantum information in solid systems.

关 键 词：量子光学 热纠缠 并发度 海森堡自旋链 时变外磁场 

分 类 号：O431.2[机械工程—光学工程]