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arXiv quant-ph/0411189quant-ph
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开放量子系统

Open quantum systems

A. Isar, A. Sandulescu, H. Scutaru, E. Stefanescu, W. Scheid

摘要:

在开放量子系统的Lindblad理论框架下研究了谐振子的阻尼。本文对阻尼量子振子主方程中的量子力学扩散系数的基本约束进行了推广,明确给出了林德布拉德方程的薛定谔、海森堡和Weyl-Wigner-Moyal表示.在这些表示的基础上,它表明,文献中使用的阻尼量子振荡器的各种主方程是林德布拉德方程的特殊情况,并不是所有这些方程都满足量子力学扩散系数的约束。将主方程转化为准概率分布的Fokker-Planck方程,并对Glauber $P$表象、反正规序$Q$表象和Wigner $W$表象进行了比较研究.密度矩阵通过生成函数表示,生成函数通过求解从主方程导出的时间相关的线性偏微分方程获得。本文用阻尼谐振子描述了在深度非弹性反应中观察到的电荷平衡模式。对于由两个谐振子组成的系统,得到了期望值、Wigner函数和Weyl算子的时间依赖性,并讨论了它们的性质。此外,模型的阻尼角动量进行了研究。将该理论应用于原子与光场的共振相互作用,得到了描述原子与光场通过环境耦合的新的光学方程。

英文摘要:

The damping of the harmonic oscillator is studied in the framework of the Lindblad theory for open quantum systems. A generalization of the fundamental constraints on quantum mechanical diffusion coefficients which appear in the master equation for the damped quantum oscillator is presented; the Schrödinger, Heisenberg and Weyl-Wigner-Moyal representations of the Lindblad equation are given explicitly. On the basis of these representations it is shown that various master equations for the damped quantum oscillator used in the literature are particular cases of the Lindblad equation and that not all of these equations are satisfying the constraints on quantum mechanical diffusion coefficients. The master equation is transformed into Fokker-Planck equations for quasiprobability distributions and a comparative study is made for the Glauber $P$ representation, the antinormal ordering $Q$ representation and the Wigner $W$ representation. The density matrix is represented via a generating function, which is obtained by solving a time-dependent linear partial differential equation derived from the master equation. The damped harmonic oscillator is applied for the description of the charge equilibration mode observed in deep inelastic reactions. For a system consisting of two harmonic oscillators the time dependence of expectation values, Wigner function and Weyl operator are obtained and discussed. In addition models for the damping of the angular momentum are studied. Using this theory to the quantum tunneling through the nuclear barrier, besides Gamow's transitions with energy conservation, additional transitions with energy loss, are found. When this theory is used to the resonant atom-field interaction, new optical equations describing the coupling through the environment are obtained.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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