Kerr介质中受激三能级原子的场熵演化特性

Entropy Evolution Properties of the Field in Kerr Medium with an Excited Three-level Atom

本文研究了在Kerr介质中单模相干场与“A”型三能级原子相互作用的场熵演化规律,讨论了Kerr介质及初始场的平均光子数(初始场强)对场熵演化的影响。研究结果表明:初始场的平均光子数n影响了场熵演化的周期性,在初始场强n不太大(约n<40)的情况下,随着n的增加,场熵演化曲线的均值不断增大,光场与原子的关联程度增强;而在强场条件下(约n>40),初始场强n的增加将导致光场与原子的关联程度逐渐减弱直至脱耦。Kerr介质强度系数μ同样影响着场熵演化的周期性,随着μ的增大,场熵演化曲线的Rabi振荡频率明显变快,而其最大值却不断减小,这表明:场熵敏感于Kerr介质的非线性相互作用,非线性Kerr介质的存在会削弱场与原子的相互作用。

In this paper, the evolution of field entropy of the interaction between A-type three-level atom and single-mode coherent field in a Kerr medium is studied. The influences of the Kerr medium and of the initial mean photon number n (the initial field intensity) on the entropy is discussed. It has been shown that the periodicity of the evolution curves of the field-entropy is influenced by the initial mean photon number n. With the increase of the initial field intensity n, the mean values of the evolution curves of the field entropy increase constantly when the initial field intensity n is not big (about n<40), therefore, the related degree of the field-atom strengthens. And in the condition of strong field (about n > 40), with the increase of the initial field intensity n, the related degree of the field-atom decreases constantly and disappears. The Kerr medium intensity parameter μ also has influences on the periodicity of the evolution curves of the field- entropy. With the increase of μ, the Rabi oscillation frequency of the evolution curves of the field entropy becomes rapid obviously. But its maximal value decreases constantly. This shows that the field entropy is susceptible to the non-linearity action of Kerr medium. And the non-linearity action of Kerr medium can weaken the interaction of the field-atom.