利用热纠缠态表象求解密度算符主方程方法,考虑双模压缩真空态中的一模经过激光过程衰减的情况,给出了双模压缩真空态在该过程中密度算符的演化规律。采用数值计算方法,讨论了一模的衰减和压缩参数变化对态的压缩效应、反聚束效应、Cauchy-Schwartze不等式违背和两模间纠缠等量子特性的影响。研究结果表明:随耗散时间增大,光场的压缩效应、反聚束效应、Cauchy-Schwartze不等式违背和两模间纠缠等特性都逐渐减弱,直至消失。另一方面,随双模压缩参数增大,压缩效应、反聚束效应、Cauchy-Schwartze不等式违背和两模间纠缠等量子特性均增强。

Master equation of density operators in laser process can be concisely solved by virtue of thermo-entangled state representation.We consider the case in which one model light field in the two-mode squeezed vacuum state evolves in a laser channel.The evolution formula of the field density operator is given in the two-mode squeezed vacuum state initially.Its nonclassical properties,such as squeezing effect,anti-bunching effect,the violation of Cauchy-Schwartze inequality and the entanglement property between two modes,are investigated.Numerical results show that its nonclassical properties are weakened with the increase of dissipation time,until it disappears.On the other hand,its nonclassical properties are strengthened with the increase of squeezing parameter.