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arXiv 0910.0356quant-phcond-mat.mes-hall
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强交流驱动下的耗散二能级系统：Floquet和Van Vleck微扰理论的结合

The dissipative two-level system under strong ac-driving: a combination of Floquet and Van Vleck perturbation theory

Johannes Hausinger, Milena Grifoni

备注：
21 pages, 18 figures; published version
发表信息：
Phys. Rev. A 81, 022117 (2010)
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摘要：

研究了强交流驱动下的二能级系统的耗散动力学。通过在TLS隧道矩阵元中结合Floquet理论和Van Vleck微扰理论，我们对角化了含时哈密顿量，并对TLS的重整化Rabi频率进行了修正，这些修正对有偏和无偏TLS都有效，并超越了已知的高频和行波结果.为了模拟环境对TLS的影响，我们将系统弱耦合到热浴，并解析求解相应的Floquet-Bloch-Redfield主方程。我们给出了TLS弛豫和退相速率的封闭表达式，并讨论了它们在驱动振幅变化下的行为。此外，我们还研究了相干破坏隧穿（CDT）和驱动诱导隧穿振荡（DITO）的鲁棒性。我们表明，也为一个温和的驱动频率几乎完全抑制隧穿可以实现短时间内，并证明DITO的外部参数的变化的敏感性。

英文摘要：

We study the dissipative dynamics of a two-level system (TLS) exposed to strong ac driving. By combing Floquet theory with Van Vleck perturbation theory in the TLS tunneling matrix element, we diagonalize the time-dependent Hamiltonian and provide corrections to the renormalized Rabi frequency of the TLS, which are valid for both a biased and unbiased TLS and go beyond the known high-frequency and rotating-wave results. In order to mimic environmental influences on the TLS, we couple the system weakly to a thermal bath and solve analytically the corresponding Floquet-Bloch-Redfield master equation. We give a closed expression for the relaxation and dephasing rates of the TLS and discuss their behavior under variation of the driving amplitude. Further, we examine the robustness of coherent destruction of tunneling (CDT) and driving-induced tunneling oscillations (DITO). We show that also for a moderate driving frequency an almost complete suppression of tunneling can be achieved for short times and demonstrate the sensitiveness of DITO to a change of the external parameters.

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