耗散腔中多光子J-C模型中的密度算符间距

研究了腔场存在相位耗散时多光子J-C模型中光场、原子和系统的密度算符间距;讨论了原子初始态、光场强度以及腔场耗散系数对密度算符间距的影响;且比较了不同跃迁光子数下体系的密度算符间距.结果发现:①密度算符间距与原子的初始态密切相关.②光场和系统的密度算符间距在耗散腔中作减幅周期振荡最终达到稳定,达到稳定所需时间随腔的耗散系数增大而缩短;而原子的密度算符间距与腔的耗散无关.③随着光场初始强度的增加,光场和系统与各自初始态的偏离程度增大.④对于双光子跃迁,当腔场存在相位损耗时光场和系统的密度算符间距仍作减幅周期振荡,原子仍周期性的回到纯态.但由于光场与原子的纠缠和退纠缠速率加快,密度算符间距在每个周期内振荡加剧.

The distances between density operators in Multi-photon J-C Model in a phase damping cavity

In the multi-photon J-C Model in the presence of phase damping of the cavity, the distances between density operators of the field, atom and system are investigated .The effects of atomic initial states, the damping coefficient of cavity and the intensity of field on the distances are discussed. It is found that the distances depend closely on the initial states of atom. The distances of the field and the whole system show damped oscillatory behavior and their amplitudes decrease due to the phase damping. The larger the damping coefficient becomes, the more rapidly the distances of the field and system decay. However, the atomic distance is independent of the phase damping. On the other hand, the stronger the initial intensity of field is, the farer the field and system departure from their initial states. Finally the distances between density operators in this model with one-photon and two-photon transition are compared. For the two-photon transition, the atom still returns to pure state in the same period as that in single-photon transition. But due to the rate of disentanglement and entanglement between atom and field becomes more rapid, the distances oscillate more rapidly within each period.