两格点两电子Hubbard-Holstein模型极化子的量子纠缠特性  

Two-site Hubbard-Holstein model polaron of quantum entanglement properties

作　　者：任学藻[1] 贺树[1] 丛红璐[2] 王旭文[1] 

机构地区：[1]西南科技大学理学院,绵阳621010 [2]北京交通大学海滨学院,黄骅061100

出　　处：《物理学报》2012年第12期269-275,共7页Acta Physica Sinica

基　　金：国家自然科学基金委员会-中国工程物理研究院联合基金(批准号:10976025/A06)资助的课题~~

摘　　要：本文利用相干态正交化展开方法,对两格点两电子Hubbard-Holstein极化子模型的能谱以及动力学特性进行了精确求解.讨论了耦合强度g、平均声子数n以及电子初态对纠缠演化特性及系统冯诺依曼熵的影响.数值计算结果表明:1)纠缠度随时间的演化呈现出良好的周期性,当其他的参数固定时,演化周期随耦合强度g增大逐渐减小,与平均声子数n无关;2)系统冯诺依曼熵同电子状态占有率表现出严格的同步演化特性;(3)在弱耦合强度和低平均声子数下,初始电子态c_(2↓)^+c_(2↓)^+|0>_e或c_(1↑)^+c_(1↓)|0>_e。较c_(1↑)^+c_(2↓)^+—c_(1↓)^+c_(2↑)^+具有更大的最大冯诺依曼熵,并随耦合强度增大、平均声子数的增加而逐渐接近.We obtain the exact solution of energy spectrum and dynamics for the two-site Hubbard-Holstein model by the coherent states orthogonal expansion method. The influences of coupling strength g, the average number of phonons and the initial electronic state on the evolution of system entanglement and yon Neumann entropy are discussed. Numerical results are as follows. （a） Entanglement evolution with time shows a good periodicity. When the other parameters are fixed, the evolution period decreases as the coupling strength g goes up but it is independent of the average number of phonons h. （b） The yon Neumann entropy of the system demonstrates strict synchronia with the electronic state occupancy probability. （c） Under the weak coupling strength and low average number of phonons, the initial electronic state c2＋↑c2＋↓10） or c1＋↑c1＋↓10）e shows larger maximum von Neumann entropy during its evolution than that of c1＋↑c2＋↓10）-c1＋↑c2＋↓10 ;but they gradually approach to each other with the increase of coupling strength or average number of phouons.

关 键 词：相干态正交化展 Hubbard-Holstein模型 极化子 场熵 

分 类 号：O431.2[机械工程—光学工程]