本文采用时间演化算符方法和数值计算研究了相干光场与混合态二能级原子双光子过程的粒子数反转特性，结果表明：量子崩塌与复苏性质和原子初始的混合程度无关，但振荡最大幅值受原子初始混合程度的支配，随着原子初始混合程度的增大，原子反转几率减小；在强场作用下，这种量子崩塌与复苏性质，将随着ｎ值的不断增大而重复地出现复苏收缩现象，且场与原子的非线性耦合越来越强 In this paper, we use the time-evolution operator method and the numerical calculation to study the inversion of the number of particles in the two-photon process of coherent light field and mixed two-level atom. The results show that the nature of quantum collapse and recovery is not related to the initial mixing degree of atoms, The maximum amplitude is governed by the initial mixing degree of the atoms. As the initial mixing degree of the atoms increases, the probability of atomic inversion decreases. Under the action of a strong field, the nature of the quantum collapse and recovery will increase as the value of n increases Larger and more repeated shrinkage phenomenon occurs, and the coupling of field and atom is stronger and stronger