原子能级简并的双光子J-C模型耗散动力学

研究原子能级简并的双光子Jaynes-Cummings模型中原子和系统的耗散动力学，应用密度矩阵主方程对腔耗散常数进行微扰展开的方法，在不同的光腔耗散常数及平均光子敷下，分别计算了系统与原子线性熵随时间的演化关系．结果显示，原子能级的简并增加了系统与原子初始相干性，延长了原子与场之间的纠缠周期，同时压缩了这种纠缠的振幅．另外，光场经典性越强，退相干发生越迅速，系统陷入混乱度越高．

Dissipation dynamics of two-photon Jaynes-Cummings model with degenerate atomic levels

In order to study the dissipative properties of system and atom in the two-photon Jaynes-Cummings model (JCM) with degenerate atomic levels, the method of perturbative expansion of density matrix master equation with respect to cavity dissipation coefficient is employed to calculate the evolution of system and atomic linear entropy versus time respectively, under different cavity dissipation coefficients and mean photon number. The results show that the degeneracy of atomic levels increases the initial coherence of system and atom, prolongs the period of entanglement between the atom and the field and depresses the amplitude of this entanglement. Besides, the larger the classical intensity of the field, the more rapidly the decoherence takes place, and finally the system will fall in much more confused state.