New approach for deriving the exact time evolution of density operator for diffusive anharmonic oscillator and its Wigner distribution function |
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Authors: | Meng Xiang-Guo Wang Ji-Suo Liang Bao-Long |
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Institution: | a Department of Physics, Liaocheng University, Liaocheng 252059, China;b Shandong Provincial Key Laboratory of Laser Polarization and Information Technology, College of Physics and Engineering,Qufu Normal University, Qufu 273165, China |
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Abstract: | Using the 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 calculation of the WF to an overlap between two pure states in an enlarged Fock space. It is found that this formula brings us much convenience to investigate 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 the diffusive AHO. |
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Keywords: | diffusive anharmonic oscillator thermal entangled state representation infinitive operator-sum representation Wigner function |
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