Theory of damped Rabi oscillations at finite temperatures
Theory of damped Rabi oscillations at finite temperatures
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DOI：
10.1088/1742-6596/150/2/022056
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发表时间：
2009-02
期刊：
影响因子：
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通讯作者：
S. Matsuo;T. Fujii;N. Kosugi;N. Hatakenaka
中科院分区：
文献类型：
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作者：
S. Matsuo;T. Fujii;N. Kosugi;N. Hatakenaka
在有限温度下，对存在耗散时的拉比振荡进行了理论研究.我们所考虑的系统是一个在交变场作用下既有内部弛豫又有外部衰变的量子二能级系统。采用由无限多个谐振子组成的集合建模的环境，以便将温度引入系统中。在Born-Markov近似下，得到了耦合到Caldeira-Leggett型环境中的量子二能级系统的密度矩阵（Liouville方程）的运动方程.利用Redfield理论将系统的内部弛豫纳入Liouville方程，得到弛豫速率与温度相关的Liouville方程。采用基于拉普拉斯变换的Torrey方法得到了精确解。阻尼拉比振荡的解可以分为基本的弛豫过程，如简单衰减和阻尼振荡。由于解的系数涉及对应于过程的物理弛豫速率，所以所有弛豫速率（诸如失相速率）通过这些不同弛豫过程中的系数的简单计算来确定。
Rabi oscillations in the presence of dissipation are theoretically studied at finite temperatures. The system that we consider is a quantum two-level system with both internal relaxations and external decays under an alternating field. The environment modeled by a set consisting of an infinite number of harmonic oscillators is employed in order to introduce temperature into the system. The equations of motion for the density matrix (Liouville equation) of such a quantum two-level system coupled to a Caldeira-Leggett-type environment are obtained with the Born-Markov approximation. Internal relaxations of the system are incorporated into the Liouville equations using the Redfield theory, resulting in Liouville equations with temperature-dependent relaxation rates. The exact solutions are obtained by using the Torrey method based on the Laplace transform. The solution for damped Rabi oscillations can be divided into elementary relaxation processes such as a simple decay and a damped oscillation. Since the coefficients of the solution involve physical relaxation rates corresponding to the processes, all the relaxation rates such as the dephasing rate are determined by simple calculations of the coefficients in these different relaxation processes.