混沌微扰导致的量子退相干  

Decoherence by a classically small influence

作　　者：赵文垒[1,2,3] 王建忠[1] 豆福全[1] 

机构地区：[1]北京理工大学物理学院,北京100081 [2]北京应用物理与计算数学研究所,计算物理国家重点实验室,北京100088 [3]北京大学应用物理与技术研究中心,高能量密度物理数值模拟教育部重点实验室,北京100084

出　　处：《物理学报》2012年第24期25-29,共5页Acta Physica Sinica

基　　金：国家高技术研究发展计划(863计划)(批准号:2011AA120101);国家重点基础研究发展计划(973计划)(批准号:2011CB921503)资助的课题~~

摘　　要：研究了无限深势阱内两个粒子的耦合导致的量子退相干和量子行为趋近于经典混沌运动的过程.当一个粒子的质量减小时,它对另外一个粒子经典混沌扩散的影响逐渐减小.强混沌机理使得轻粒子的作用类似于噪声,从而有效得抑制另外一个粒子的量子相干性.轻粒子的退相干效应随着有效普朗克常数的减小逐渐增强.在这个过程中,另外一个粒子的量子扩散从动力学局域化行为逐渐过渡到经典极限.当有效普朗克常数足够小时,它的量子扩散与经典混沌扩散相符合.该粒子的线性墒随时间演化迅速趋近于饱和值,并且饱和值随着有效普朗克常数减小以指数函数形式从零趋近于1.Via a system of two kicked particles that are coupled in an infinite square well, we numerically show that the interaction with a particle of very small mass is able to lead to a quantum-to-classical transition on condition that the corresponding classical dynamics is almost unaffected. With the decrease of the mass of one of the particles, its effect on the classical dynamics of the other one decreases. Such an effect is even negligible if the mass of the particle is small enough. The classically chaotic dynamics of this small particle is effective for promoting the decoherence of the heavy particle. Therefore its quantum behavior exhibits the transition from the dynamical localization to the classically chaotic diffusion with the decrease of the effective Planck＇s constant h. Under the perturbation from the small particle, the linear entropy is rapidly saturated as time passes by. With the decrease of h, the time-averaged linear entropy exponentially increases from zero to almost unity.

关 键 词：退相干 量子-经典过渡 量子混沌 

分 类 号：O431.2[机械工程—光学工程] O415.5[理学—光学]