激光过程中真空态和单光子叠加态的量子特性  

Nonclassical properties of superposition of vacuum state and singlephoton state in laser process

作　　者：卢道明[1] 

机构地区：[1]武夷学院机电工程学院

出　　处：《光电子．激光》2014年第7期1432-1437,共6页Journal of Optoelectronics·Laser

基　　金：福建省自然科学基金(2011J01018)资助项目

摘　　要：采用热纠缠态表象和有序算符内的积分技术,通过求解密度矩阵主方程,导出了真空态和单光子叠加态在激光过程中的Wigner函数和光子数分布的解析表达式。采用数值计算方法,给出了腔场的增益和衰减常数等参数取确定值时真空态和单光子叠加态的Wigner函数、负部体积和光子数分布的演化曲线。通过比较Wigner函数负值区域的变化,讨论了耗散过程对该量子态量子特性的影响。研究结果表明:随耗散过程进行,态的Wigner函数负值范围和负值深度都在逐渐减小,直至负值消失。Master equations of density operators can be concisely solved by virtue of thermo entangled state representation and t he technique of integration within an ordered product of operators.The solution of master equations of density operators is given.We get the Wigner function evolution formula in phase space and photon number distribution formula of the state, which is a superposition of vacuum state and single-photon state initially in laser process.By numerical calculation we plot its Wigner function and photon number distributi on evolution curves,when cavity gain constant and cavity loss constant are both equal to cert ain values.The effect of decoherence on nonclassical property of the state is discussed by comparing n egative area size and the depth of negativity of Wigner function.Numerical results show that the negativity area size and the depth of negativity of its Wigner function decrease and then v anish with dissipation. In addition,we calculate the variation of negative volume of Wigner fun ction with dissipation time.We find that it decreases with dissipation time increasing.These results s how that the nonclassical properties of the state are weakened and then disappe ar with dissipation time increasing.

关 键 词：激光过程 真空态和单光子叠加态 WIGNER函数 光子数分布 

分 类 号：O431.2[机械工程—光学工程]