场频率变化时原子与场的相互作用

The interactions between an atom and a field with a time-varying frequency

讨论了场频率随时间变化时二能级原子与相干态光场的相互作用 .分析了两种典型的情况 ,即场频率随时间作正弦变化以及作脉冲变化的情况 .研究发现 :当场频率随时间作正弦变化时 ,原子布居数反转的崩塌和回复现象将消失 ;当场频率随时间作脉冲变化时 ,布居数反转随时间的演化将诱发出新的崩塌和回复过程 .

In this paper, the interactions between a two-level atom and a coherent field with a time-varying frequency have been studied. The two typical cases, in which the frequency of the field varies with time in the form of sine or impulse, have been considered. It is found that the collapse and revival phenomena of the atomic population inversion will disappear as the frequency changing with time in sine form; and the frequency varying in impulse form can lead to some new collapses and new revivals in the evolution of the atomic population inversion.