量子光场连续测量的随机主方程理论  

Stochastic Master Equation Theory for the Continuous Measurements of Quantum Optical Field

作　　者：董莹[1] 杨垂平[1] 

机构地区：[1]杭州师范大学理学院,浙江杭州310036

出　　处：《杭州师范大学学报（自然科学版）》2015年第3期225-228,246,共5页Journal of Hangzhou Normal University(Natural Science Edition)

摘　　要：利用一束二能级原子束,使之穿过光场并与其发生相互作用,通过探测穿过光场后原子的状态,获得关于光场内光子数的信息,从而实现一个关于光子数的连续弱测量过程.根据量子连续测量理论及Wiener随机过程的相关理论,推导出描述这一连续测量过程的随机Schr¨odinger方程与随机主方程.由所得方程的形式可见,如果原子与光场的相互作用为色散性的,则可以实现光场的非破坏测量,这种测量可以保证光场内的光子数在测量后不发生改变.反之如果相互作用是吸收性的,则可以实现吸收性的测量,这种测量等效于给光场附加了一个额外的真空热库,将导致光场内光子数的减少.To realize the continuous weak measurement for photon number ,a beam of two‐level atoms passes through a quantum optical field and then reads out the information about the photon number by detecting the state of the atoms leaving the optical field .According to the quantum continuous measurement theory and the Wiener stochastic process theory ,a stochastic master equation and a stochastic Schr＆168;odinger equation to describe the measurement process can be derived .The forms of the resulting equations show that if the interaction between the atom and the photon is dispersive in nature ,then the photon number in the optical field can be conserved and a quantum non‐demolition （QND） measurement can be realized .If the interaction is absorptive ,then the absorption measurement can be realized ,which corresponds to add to the optical field an additional vacuum reservoir and leads to the dissipation of the optical field .

关 键 词：连续量子测量 非破坏测量 随机主方程 

分 类 号：O431.2[机械工程—光学工程]