利用全量子化理论, 在非旋波近似下对双模相干态光场与级联型三能级原子相互作用的量子纠缠进行了精确求解.讨论了初始时刻原子能级的叠加和平均光子数对量子纠缠演化的影响.数值计算结果表明: 初始时刻原子处于单一能级时, 量子纠缠演化曲线的周期随着平均光子数的增加逐渐变大；初始时刻原子能级的叠加导致初始阶段纠缠度显著降低, 纠缠达到最大值的时间随着平均光子数的增大逐渐变长, 且初始时刻原子能级的叠加使得量子纠缠的周期性消失；无论初始时刻原子能级处于哪种能级的叠加态, 随着平均光子数的增大, 由虚光子效应引起的小锯齿状的振荡逐渐增强.

The quantum entanglement of the two mode coherent field interacting with a cascade three-level atom was calculated accurately with non-rotating wave approximation by using the complete quantum theory. The influences of the superposition between different atomic energy level at the initial time and the mean photon number on quantum entanglement evolution were considered. The results obtained by the numerical method show that the period of the quantum entanglement evolution becomes longer with the increase of the mean photon number when the atom initially at the single energy level, the quantum entanglement at the first few periods is reduced notably due to the fact of the atom is initially in the superposition state, it takes longer time for the entanglement to reach the maximum value with the increase of the mean photon number, moreover, because of the atom is initially in the superposition state, the periodic disappears. No matter which atom state, the quick oscillation due to the virtual photon process increases with the increasing of the mean photon number.