New approach for deriving the exact time evolution of the density operator for a diffusive anharmonic oscillator and its Wigner distribution function  

作　　者：孟祥国 王继锁 梁宝龙 

机构地区：[1]Department of Physics,Liaocheng University [2]Shandong Provincial Key Laboratory of Laser Polarization and Information Technology,College of Physics and Engineering, Qufu Normal University

出　　处：《Chinese Physics B》2013年第3期146-151,共6页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China (Grant Nos. 11147009 and 11244005);the Natural Science Foundation of Shandong Province,China (Grant No. ZR2012AM004)

摘　　要：Using thermal entangled state representation,we solve the master equation of a diffusive anharmonic oscillator（AHO） to obtain the exact time evolution formula for the density operator in the infinitive operator-sum representation.We present a new evolution formula of the Wigner function（WF） for any initial state of the diffusive AHO by converting the WF calculation into an overlap between two pure states in an enlarged Fock space.It is found that this formula is very convenient in investigating the WF＇s evolution of any known initial state.As applications,this formula is used to obtain the evolution of the WF for a coherent state and the evolution of the photon-number distribution of diffusive AHOs.Using thermal entangled state representation,we solve the master equation of a diffusive anharmonic oscillator（AHO） to obtain the exact time evolution formula for the density operator in the infinitive operator-sum representation.We present a new evolution formula of the Wigner function（WF） for any initial state of the diffusive AHO by converting the WF calculation into an overlap between two pure states in an enlarged Fock space.It is found that this formula is very convenient in investigating the WF＇s evolution of any known initial state.As applications,this formula is used to obtain the evolution of the WF for a coherent state and the evolution of the photon-number distribution of diffusive AHOs.

关 键 词：diffusive anharmonic oscillator thermal entangled state representation infinitive operator-sum representation Wigner function 

分 类 号：O413[理学—理论物理] O174[理学—物理]