与光场依赖强度耦合下运动纠缠双原子的周期量子回声  

Periodic Quantum Echo of Moving and Entangled Two-atom via Light Field Intensity-dependent Coupling

作　　者：刘小娟[1] 周并举[1] 姜春蕾[1] 彭朝晖[1] 刘明伟[1] 

机构地区：[1]湖南科技大学物理学院,湖南湘潭411201

出　　处：《光子学报》2012年第11期1347-1353,共5页Acta Photonica Sinica

基　　金：国家自然科学基金(No.11074072);湖南省自然科学湘潭联合基金(No.10JJ9002);湖南省教育厅重点项目(No.10A032);中国科学院红外物理国家重点实验室(No.201118;No.201119)资助

摘　　要：本文将Tavis-Cummings(T-C)模型推广到同时考虑原子运动及与光场依赖强度耦合的情况.运用全量子理论,研究了与光场依赖强度耦合下运动纠缠双原子量子态保真度演化.采用数值计算的方法,探讨了双原子初始纠缠因子、光场平均光子数n-以及场模结构参量p对双原子量子态保真度演化的影响,解析分析了双原子周期量子回声的形成规律,揭示了其物理实质.结果表明,在场模结构参量p=1的情况下,无论光强和双原子初始纠缠因子如何取值,双原子均产生周期2π的量子回声;在强相干场n-=30条件下,改变p从1到小于800时,Bell态双原子产生2π/p周期量子回声.当p≥800时,无论光场是真空场、弱相干场或强相干场,双原子量子态保真度恒为1,即第一类Bell态原子持续处于保真态;而当双原子初始纠缠因子为3π/4时,无论n-、p取何值,双原子量子态保真度保持为1,双原子持续处于第二类Bell态的保真态.其结论表明,该推广模型具有很好的双原子周期量子回声性质,为纠缠双原子信息高保真输出及噪音环境下量子信息处理的实验实现提供了理论参量和物理载体.In this paper,the Tavis-Cummings(TC) model is generalized to simultaneously consider atomic motions and fields via intensity dependent coupling.Evolution of the fidelity of quantum states of entangled two-atom with motion interacting with light field via intensity-dependence coupling is investigated by means of the full quantum theory.The effects on the evolution of the fidelity of quantum states from the initial entanglement factor  of the two-atom and the average photon number n-and field-mode structure parameter p of the field are researched by numerical calculations.The formation rule of quantum echoes of two-atoms is analyzed,and its physical essence is revealed.The results show that period quantum echo of the two-atom is always produced in the case of field-mode structure parameter p=1,independent of light intensity n-and the initial entanglement factor  of the two-atom.Bell-state atoms can produce quantum echo with 2π/p cycle on the conditions of strongly coherent field,via changing the p of from 1 to any value less than 800.When p≥800,no matter what value of  takes,the light field is a vacuum field,weakly coherent field or strong coherent field,the fidelity of quantum states of the two-atom is always 1,that is the first class Bell state-atoms is in the fidelity state continuously.But when the initial entanglement factor  of two-atom is 3π/4,no matter how both values of n-,p are,the fidelity of quantum states of the two-atom maintains 1,namely the two-atom is in the fidelity state of the second class Bell-state continuously.The conclusions show that the extension model has good properties of periodic quantum echoes of two-atom,and provides the theoretical parameters and physical carrier for high fidelity output of entangled two-atoms information and experimental implementation of quantum information processing in the noise environment.

关 键 词：依赖强度耦合 运动纠缠双原子 量子态保真度 周期量子回声 

分 类 号：O431.2[机械工程—光学工程]