等距离耦合腔系统中的非局域性

Dynamics of nonlocality in the three equidistance cavities coupled by fibers

本文研究的物理系统由3个二能级原子和3个等距离单模腔构成.3个单模腔分别处于等边三角形的3个顶点,腔与腔之间通过光纤耦合.采用Mermin-Ardehali-Belinksii-Klyshko不等式(简称MABK不等式)表征三体量子态的非局域性.本文利用数值计算方法,研究了原子初态或腔场初态为W态情况下三体系统量子态的MABK不等式违背,讨论了腔模与光纤模间的耦合系数变化对MABK不等式违背的影响.计算结果表明:三原子量子态和三腔场量子态均呈现出MABK不等式违背,并且随腔模与光纤模间耦合系数增大,三原子量子态的非局域性增强.

Entanglement and nonlocality,two most striking features of quantum mechanics,are fundamental resources for quantum information processing.They play an important role in quantum information processing.Therefore,studying the dynamics of quantum nonlocality and entanglement is of importance for both fundamental research and practical applications.In this paper we consider the case that three identical two-level atoms are trapped respectively in the three separated equidistance single-mode cavities,which are placed at the vertices of an equilateral triangle and are coupled by three fibers.Each atom resonantly interacts with cavity via a one-photon hopping.The evolution of the state vector of the system is given by solving the schrodinger equation when the total excitation number of the system equals one.The dynamics of nonlocality in the system is investigated via Mermin-Ardehali-Belinksii-Klyshko（MABK）inequality.By the numerical calculations,the MABK inequality is studied when the initial state vector of three atoms is W state or the initial state vector of three cavities is also W state.The influence of cavity-fiber coupling constant on the MABK inequality is discussed.The evolution curves of the MABK parameters Ba and Bc are plotted.The curves show that Ba and Bc both display periodic oscillations,and their oscillation frequencies all increase with the increase of cavity-fiber coupling constant.Ba and Bc are both larger than 1 when the scaling time gt takes a certain value.The results show that the quantum state of three atoms or that of three cavities displays nonlocality.On the other hand,the nonlocality of three-atom quantum state is strengthened with the increase of cavity-fiber coupling constant.