内禀退相干下薛定谔猫态光场与原子相互作用系统的场熵演化

通过求解系统的Milburn方程，研究了二能级原子与薛定谔猫态光场相互作用系统中的场熵演化特性.讨论了内禀退相干，光场强度，相干态间的相位角对场熵演化的影响.结果表明: 内禀退相干下，随着时间的演化，场熵振荡逐渐减弱，光场与原子的纠缠度逐渐趋于恒值.并且光场与原子的最大纠缠度值只取决光场强度和相干态间的相位角，与内禀退相干因子无关.光场强度较小时，奇相干态光场与原子的纠缠度最大；偶相干态光场与原子的纠缠度值为最小；Yurke-Stoler相干态光场与原子的纠缠度值介于两者之间. 当内禀退相干因子不变、光场强度较大时，分别处于Yurke-Stoler相干态、偶相干态和奇相干态的光场与原子的纠缠度值趋近于相同.

The Field Entropy Evolution of Schrödinger Cat State Light Field interacting with the Atom under Intrinsic Decoherence Condition

The field entropy evolution in a system of the Schrödinger cat state light field interacting with a two-level atom was studied by solving Milburn equation. The influences of intrinsic decoherence, the strength of light field and the phase angle between the two coherence states on the field entropy evolution was discussed. The results show that the field entropy vibration will be weak gradually because of the intrinsic decoherence, and the degree of entanglement in the field-atom system approaches to a certain value with time evolution. Furthermore, the max degree of entanglement in the field-atom system only depends on the strength of light field and the phase angle between the two coherence states, and have nothing to do with intrinsic decoherence. When the strength of light field is relatively small, the degree of entanglement is maximum in a system of a two-level atom interacting with an odd coherence state light field, and it is minimum in a system of a two-level atom interacting with an even coherence state light field; it is intermediate for a system of a two-level atom interacting with Yurke-Stoler coherence state light field. When the intrinsic decoherence is fixed and the strength of light field is relatively large, the degree of entanglement in the field-atom system existing in the Yurke-stoler, the even coherence state and odd coherence state tend to the same.