失谐量对多模场非简并多光子Jaynes-Cummings模型量子场熵演化的影响

利用Von Neumann约化熵理论研究了多模相干态场与二能级原子非简并多光子相互作用系统中量子场熵的时间演化特性,得到了含有失谐量的多模场熵的解析表达式,并通过数值计算讨论了光场为三模场时频率失谐量对场熵演化的影响.结果发现：当近共振时,失谐量几乎不影响场与原子之间的纠缠特性;而当远离共振时,量子场熵很强地依赖于失谐量的大小,特别是当失谐量足够大时,场与原子几乎总是处于纠缠态.

Influence of Frequency Detuning on Evolution of Quantum Field Entropy in Multimode Nondegenerate Multi-Photon Jaynes-Cummings Model

The time evolution of the field quantum entropy in the system of a multi-mode coherent field interacting with a two-level atom through the non-degenerate multi-photon process is investigated using the Von Neumann reduced entropy, the analytical expression of the multimode field entropy including the frequency detuning is obtained. The numerical results for the three-mode field interacting with the atom are presented. The influence of the frequency detuning on the field quantum entropy is discussed. It is found that the frequency detuning has nearly no effect on the entanglement between the three-mode coherent field and the two-level atom when the field and the atom are near resonance, but the time evolution of the field quantum entropy is strongly dependent on the values of the frequency detuning when the field and the atom are far from resonance, especially when the frequency detuning is large enough, the field and the atom are nearly always in entangled states.