耗散腔场中两个∧型原子的纠缠特性

利用超算符方法求解幅值损耗腔中两个∧型三能级原子与相干光场相互作用系统的主方程,并利用量子条件熵研究了两个初始为|Ψa(0)＞和|Φa(0)＞纠缠态的原子与光场作用过程中原子的纠缠演化特性.讨论了不同初始原子纠缠度,不同耗散系数以及不同平均光子数对两原子纠缠度的影响.结果表明:①当原子初始处于|Ψa(0)＞类纠缠态时,其纠缠度随光场强度以及腔场衰减系数演化.当腔不存在耗散时,纠缠度呈周期性振荡;当腔存在耗散时,纠缠度呈衰减振荡并趋于稳定值;且光强越弱,其稳定值越大;衰减系数越大纠缠达到稳定值所需时间越短.②原子初始处于|Φa(0)＞类纠缠态时,其纠缠度只与原子初始纠缠度有关,不随其他因素变化.

The Entanglement Properties of Two A-type atoms in a Dissipative Cavity

The entanglement between two A-type three-level atoms interacting with coherent field in a dissipative cavity is investigated by means of the entanglement degree of quantum conditional entropy.A solution of the master equation is obtained by super operator method.The authors discuss the entanglement between the two atoms based on two kinds of different initial states(|Ψa(0)＞,|Φa(0)＞)and analyze the influence of decay coefficient of the cavity and mean photon number of the field on entanglement degree.In conclusion,when the atoms are initially in entangled state |Ψa(0)＞,the evolution of the entanglement degree depends on decay coefficient of the cavity and intensity of the field.If there is absence of dissipation,the entanglement degree evolves periodically;otherwise,the entanglement degree decays sharply and approaches a stable value.The weaker the intensity of the field is,the greater the stable value becomes.The greater the decay coefficient is,the faster it reaches the stable value.But for the other initial entangled state |Φa(O)＞,the entanglement between the two atoms doesnt evolve with the time.It implies that the entangled state|Φa(0)＞can be preserved in such a dissipative system.