介质腔中场-原子作用系统密度算符间距的演化  

Evolution of the Distance of Density Operators of Field-atom Interacting System in a Medium Cavity

作　　者：赖振讲[1] 许曼[1] 冯少康[1] 贺树芳[1] 

机构地区：[1]河南师范大学物理系,河南新乡453007

出　　处：《量子光学学报》2008年第4期372-378,共7页Journal of Quantum Optics

基　　金：河南省自然科学基金(No.0511010600);河南省教育厅自然科学基金(No.2006140005)

摘　　要：利用密度算符间距的概念,关注克尔介质腔中非关联双模相干态光场与V形三能级原子相互作用系统中两子系统(原子和光场)间的信息差异,通过数值计算、图形分析,讨论了不同的原子初始态和克尔效应对系统以及子系统密度算符间距的时间演化特性的影响,结果表明:首先,当不存在克尔介质时,无论原子初始处于哪种状态,系统和原子密度算符间距的振荡均呈现崩塌、复原现象。其次,随着克尔效应的增强,(1)原子初始态为激发态时,系统中原子和光场密度算符间距的演化曲线呈现周期性变化,且克尔效应越强周期性越明显;(2)原子初态为基态时,原子间距的演化曲线逐渐变成一条直线,原子末态几乎不随时间变化,处于稳态,光场间距的演化曲线在不断振荡。最后,激发态和基态原子两种情况下,随着克尔效应的增强,原子间距的值越来越小,即原子末态离初态愈来愈"近",表现了克尔介质的态囚禁效应;光场间距的值增大,即光场末态离初态越来越"远";系统间距的演化曲线保持在1,即在正交态附近振荡。By using the distance of density operators （ DDO）, we pay attention to the information differences between the field and the atom subsystems in the interacting system combined by a uncorrelated two-mode coherent field and a V-type three-level atom in a cavity filled with a Kerr-like medium is researched in the paper. Through numerical calculation and picture methods, the influence of initial states of the atom and Kerr strength on the DDO time-dependent evolution of the whole system as well as that of the two subsystems is discussed and the results show that： First, in the absent of kerr-like medium, for arbitrary initial states of the atom （ i. e. excited and basis state） , the DDO evolution of the system and atom present collapse and revival phenomenon. Second, with the increase of the Kerr strength, （ 1 ） when atom is in excited state initially, the DDO evolution of the atom and field present periodic change, and the larger the Kerr strength is the clearer the periodicity is. （2） When atom is in basic state initially, the DDO evolution of the atom approaches a line, the final state of the atom remains unchangable approximately during the interacting time, but the DDO evolution of the field is oscillating all the time. Finally, in the two initial conditions （i. e. the atom is in excited and ground states） , with the Kerr strength increasing, the DDO of the atom is decreasing, it is to say that the atom is prefer to staying in initial state, and that reflects the trapped effects of Kerr-like medium; the DDO of the field become larger, the distance between the initial and final state of the field becomes farther, this case is due to the interaction of the field and Kerr-like medium; the DDO evolution of the whole system maintain oscillating at the unity （i. e. orthogonal state） hereabout.

关 键 词：密度算符间距 非关联双模相干光场 克尔介质 V形三能级原子 

分 类 号：O431[机械工程—光学工程]