在非旋波近似下, 对Tavis-Cummings模型的能谱和量子纠缠进行了精确求解; 将该非旋波近似下的能谱精确解与旋波近似下的结果进行了比较。讨论了初始时刻原子状态参数θ, 以及光场与原子间的耦合强度对量子纠缠的影响。结果表明, 当耦合强度较小时, 旋波近似下的能谱与精确解相符; 当耦合强度较大时, 二者存在明显差异。随着θ的增大, 纠缠度逐渐增加; 随着耦合强度的增大, 两原子间出现纠缠突然死亡的现象, 且首次出现纠缠突然死亡的时间变短, 纠缠死亡持续时间逐渐增加。

The energy spectrum and the quantum entanglement in the Tavis-Cummings model are exactly solved, without the rotating wave approximation, and this exact solution of the energy spectrum is compared with the result under the rotating wave approximation. The influences of the atom state parameter θ and the atom-field coupling intensity at the initial time on the quantum entanglement are discussed. The results show that, when the coupling intensity is relatively weak, the energy spectrum under the rotating wave approximation is consistent with the exact solution. When the coupling intensity is relatively strong, there exist obvious differences between them. With the increase of θ, the entanglement degree increases gradually. With the increase of the coupling intensity, the phenomenon of entanglement sudden death between two atoms occurs. Moreover, the first occurrence time of entanglement sudden death becomes short and the duration of the entanglement death increases gradually.