压缩真空态中二能级原子简并双光子过程的广义Bloch-Siegert频移

Generalized Bloch Siegert Shift for a Two level Atom in a Squeezed Vacuum via Degenerate Two photon Processes

用密度算符主方程方法研究了一二能级原子与宽带压缩真空态光场的简并双光子相互作用。我们发现原子偶极矩随时间的变化与压缩真空态光场的压缩参数｜Ｍ｜有关。｜Ｍ｜存在一个阈值Γ４ｇ。阈值之下，原子偶极矩以共振频率振荡；阈值之上，原子偶极矩以三种不同的频率振荡，其中中心频率仍为共振频率，两边频是由中心频率频移而得，这种现象即广义Ｂｌｏｃｈ－Ｓｉｅｇｅｒｔ频移，频移量与压缩真空态场的压缩参数有关。产生广义Ｂｌｏｃｈ－Ｓｉｅｇｅｒｔ频移的原因是双光子过程中压缩真空态光场对原子具有一种“驱动作用”的结果。

The interaction of a two level atom with a broad band squeezed vacuum via degenerate two photon processes is investigated. We find that the atomic dipole moment is dependent on the degree of squeezing . There is a threshold for the squeezing parameter |M|. Below the threshold, the atomic dipole moment oscillates with resonance frequency only. Above the threshold, however, it oscillates with three different frequencies. Two of the frequencies are shifted from the central one. This is called generalized Bloch Siegert shift (GBSS). The reason that gives rise to GBSS is also given.