增光子相干态光场与二能级原子相互作用中的含时维格纳函数

Time-Dependent Wigner Function of the Photo-added Coherent Light Interacting with a Two-level Atom

关键词:  量子光学  增光子相干态光场  维格纳函数  约化密度算符

Key words:  quantum optics  photo-added coherent states  Wigner function  reduced-density operator

摘要:

利用相互作用表象中增光子相干态光场与二能级原子作用的系统动力学波函数,通过约化密度算符和维格纳函数福克基矢展开技术得到描述光场随时间演化的含时维格纳函数,并用数值模拟分析该维格纳函数随时间演化及随光场振幅变化的特点.模拟结果显示,在随时间演化时,维格纳函数的负值性在单光子过程中不具周期性,在双光子过程中具有周期性;在随光场振幅变化时,维格纳函数的负值性随光场振幅的增强而逐渐减弱,光场的非经典特性逐渐趋近于经典特性.

Abstract:

By using the dynamical wave function,the evolution of the system of the photo-added coherent light and a two-level atom in the interaction picture are described.The time-dependent Wigner function can be obtained from these technologies by reducing-density operator and the expansion in Fock states. The properties of wigner function changed by the time and the amplitude of the light field are analyzed by the numerical simulation. And the results show that the negative of the Wigner function varying with the time takes on certain periodicities in the two-photon process,but not in the one-photon process. Meanwhile, the negative value of the Wigner function is gradually decreased when the amplitudes of light field increase, which means the non-classical characteristic tends to be the classical one.