扩散过程中弱相干光场的退相干

Decoherence of Weak Coherent State in the Diffusion Process

研究了扩散过程中弱相干光场量子特性的演化.利用正规乘积、反正规乘积和Weyl编序算符内的积分技术,采用热纠缠态表象求解密度矩阵主方程,利用Kraus算符给出扩散过程中密度算符解的表达式,导出初态为弱相干态的量子态密度算符演化规律.讨论了扩散对光场压缩效应和反聚束效应的影响.结果表明:随着扩散过程的进行,弱相干场压缩深度和压缩范围均在减小;扩散初期光场呈反聚束效应,扩散时间大于一定值后反聚束效应消失.

The quantum properties of weak cohetent state in terms of squeezing effect and antibunching effect were investigated in the diffusion.Master equation of density operator in the diffusion process can be concisely solved by virtue of thermo-entangled state representation and the technique of integration within an ordered product of operators,which contains normal ordering,antinormal ordering and Weyl ordering.The solution of master equation of density operator in diffusion process was given by Kraus operator.The evolution formula of the field density operator which is in weak coherent state initially was get.Its squeezing effect and antibunching are investigated by the numerical method.The effect of decoherence on its nonclassical property is discussed.Numerical results show that compression depth is weakened and the compression range decreases with diffusion time increasing.On the other hand,the light field displays antibunching effect in the early diffusion.When the diffusion time is greater than a certain value,its antibunching effect disappears.