中文摘要：

研究了非旋波近似下频率随时间变化的相干态光场与二能级原子的相互作用，主要讨论了光场频率随时间作正弦和方波变化两种典型情况下，原子布居数反转随时间的演化特性．当光场频率随时间作正弦变化时，原子布居数反转的崩塌．回复过程和由虚光子过程引起的快速振荡均会受到影响．当光场频率随时间以方波形式变化时，脉冲调制不仅在原子布居数反转随时间演化过程中诱导出新的崩塌．回复过程，而且可以引起虚光子快速振荡的突变．

英文摘要：

The interactions between a two-level atom and a coherent field with a time-varying frequency without rotating-wave approximation have been investigated.. The typical cases of the frequency of the field varying with time in the sine and rectangle forms have been considered. It is found that the collapse-revival phenomena and quick oscillations due to virtual photon processes of the atomic population inversion are deformed as the frequency changes with time in the sine form. The rectangular frequency modulation can lead to some new collapses and revivals in the evolution of the atomic population inversion. The sudden jumping of the field frequency can also lead to the sudden change of the quick oscillations due to virtual photon processes.