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arXiv 1006.0433cond-mat.stat-mech
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过阻尼棘轮中的低温量子涨落

Low-temperature quantum fluctuations in overdamped ratchets

Stefan A. Maier, Joachim Ankerhold

摘要:

在低温和强摩擦下,位置密度分布的时间演化遵循量子Smoluchowski方程。最近,也已系统地导出了量子涨落对漂移和扩散系数的高阶贡献。作为一种非平凡的情形,为了揭示次级量子修正的影响和证明微扰级数的收敛性质,研究了棘轮中的定向输运。结果表明,扰动级数通常具有非单调的行为。根据对称性,高阶贡献甚至可以补偿由领先的量子涨落引起的电流反转。这个分析演示了如何一致地处理过阻尼量子系统的动力学在低温下也在数值应用。

英文摘要:

At low temperatures and strong friction the time evolution of the density distribution in position follows a quantum Smoluchowski equation. Recently, also higher-order contributions of quantum fluctuations to drift and diffusion coefficients have been systematically derived. As a non-trivial situation to reveal the impact of subleading quantum corrections and to demonstrate convergence properties of the perturbation series, directed transport in ratchets is studied. It is shown that the perturbation series typically has a non-monotonous behavior. Depending on symmetry properties higher order contributions may even compensate current reversals induced by leading quantum fluctuations. This analysis demonstrates how to consistently treat the dynamics of overdamped quantum systems at low temperatures also in numerical applications.

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