利用双模SU(1,1)相干态场与四能级原子相互作用系统的态函数导出了场熵的计算公式,研究了初始光场参量和原子与光场间的耦合系数对场熵演化的影响.数值计算表明:随着初始场q和ζ参量的增加,场熵的均值逐渐增加,振荡频率增大,场熵演化的周期性随ζ的增加渐趋明显,但振荡幅度却明显减小.同时,随耦合系数的增大,场熵演化曲线的均值变化不明显,而其振荡频率急剧增大,振荡幅度也有所减小且趋于稳定,场熵敏感于原子与光场耦合系数.

Using the method of the systematic state vector the field entropy of the two-mode SU(1,1) coherent states field interacting with four-level atom has been formulated.The influences of the initial field strength and the atom-field coupling constant on the field entropy have been investigated. The results obtained by means of numerical show that. With the increase of the initial field parameter q and ζ, the mean values of the evolution curves of the field entropy increase constantly and so do the oscillation frequency of the evolution curves of the field entropy. The larger the value of ζ is. the more obvious the periodicity of the evolution curves of the initial field entropy are, but the obviously smaller the oscillation amplitude values become. With the increase of the coupling constant, the mean values of the evolution curves of the field entropy do not obviously change, but the oscillation frequency increase largely, the oscillation amplitude decrease a little and get to stability after some time, This show that the field entropy is susceptible to the atom-field coupling constant.