耗散腔中简并Raman耦合系统中光场的相位特性

利用Pegg-Barnett相位理论,研究了耗散腔中两个A型原子与相干态光场在Raman相互作用下光场的相位特性,并讨论了光场平均光子数和腔场耗散系数对光场相位特性的影响.结果表明:当腔不存在损耗时,光场相位分布概率以π/λ作周期性振荡;且在t=nπ/λ时刻,光场和原子是退纠缠的,相位分布概率曲线在极坐标图中呈单叶型结构;但在演化周期内,由于光场与原子的相互作用相位分布概率曲线会劈裂为多叶型结构.当腔场存在损耗时,相位分布概率的叶型结构会向中心扩散最终变为一个圆,即表明在考虑腔场耗散时光场的相位最终会变为随机分布;而且腔的耗散系数越大,光场相位越快趋于随机分布.另外,随光场的平均光子数增大,光场相位分布趋于集中.光场相位涨落受到腔场耗散的影响呈现出衰减周期振荡最终达到稳定值,而且达稳定值所需时间随耗散系数的增大而缩短.

The Phase Properties of the Field Interacting with A-type Atoms via Raman Coupling in a Dissipative Cavity

By means of Pegg and Barnett phase formalism, the phase properties of the field interacting with two A-type three-level atoms via Raman coupling in a phase damped cavity is discussed. The influences of decay coefficient of the cavity and the intensity of the field on the phase distribution as well as its fluctuation are discussed. The results show: if there is absence of the phase damping, the phase distribution oscillates with the period π/λ. It presents single leaf at t=nπ/λ, but it splits into multi-leaf construction during the evolution period due to the interaction between the field and the atoms. If there is presence of the phase damping, the obvious leaf construction of the phase distribution become obscure and contract into a circle, which indicates the random distribution of the phase. Moreover, the larger the decay coefficient is, the more rapidly the phase becomes random distribution. The narrowing of the leaf and the increasing amplitude of the phase distribution corresponds to a stronger field. The phase fluctuation shows damped oscillatory behavior and ultimately reaches a steady value in the phase damped cavity. The time for it to approach the steady value shortens when decay coefficient increases.