活性涨落驱动的周期系统中的反常输运
Anomalous transport in periodic systems driven by active fluctuations
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中文总结 AI 辅助
本文研究活性涨落驱动布朗粒子在周期势中的反常输运，揭示巨输运增强、绝对负迁移率和棘轮效应，并建立跳跃-弛豫模型及超简约模型以解释机制。
中文摘要 AI 辅助
本论文研究了在周期性势垒景观中由活性涨落驱动的布朗粒子的输运现象。与热噪声不同，活性涨落破坏了细致平衡并违反了涨落耗散定理。它们模拟了生物和合成微系统中的自推进机制和活性浴相互作用。通过聚焦于具有非高斯振幅统计的白泊松散粒噪声，本工作系统地揭示了控制三种主要输运反常的机制：巨输运增强、绝对负迁移率和棘轮效应。结合蒙特卡洛模拟和解析建模，本工作证明遵循双向偏斜正态振幅分布的活性涨落相比自由粒子可将定向速度增强数个数量级。这种巨输运增强通过一个现象学的跳跃-弛豫模型被完全量化，该模型将粒子位移分解为瞬时随机跳跃和向势能最小值的确定性弛豫。将该模型扩展到惯性动力学揭示，有限粒子质量 m 充当动态控制参数，能够根据噪声方差增强、减弱、建设性诱导或完全抑制输运增强。此外，在一维纯过阻尼系统中建立了一个用于绝对负迁移率的超简约模型，表明不连续散粒噪声在不需要粒子惯性、空间周期势的非线性或显式时间周期驱动的情况下，驱动输运方向与外加偏置相反。相反，在平均随机力的另一种缩放下，涨落振幅的不对称分布通过零偏置极限中的倾斜棘轮效应产生净定向输运。
英文摘要
This dissertation investigates the transport of Brownian particles driven by active fluctuations in periodic potential landscapes. Unlike thermal noise, active fluctuations break detailed balance and violate the fluctuation-dissipation theorem. They model self-propulsion mechanisms and active-bath interactions in biological and synthetic micro-systems. By focusing on white Poisson shot noise with non-Gaussian amplitude statistics, this work systematically uncovers the mechanisms governing three major transport anomalies: giant transport enhancement, absolute negative mobility, and the ratchet effect. Combining Monte Carlo simulations with analytical modeling, this work demonstrates that active fluctuations adhering to a bidirectional skew-normal amplitude distribution enhance directed velocity compared to the free-particle by several orders of magnitude. This giant transport enhancement is fully quantified via a phenomenological jump-relaxation model that decouples particle displacement into instantaneous stochastic jumps and deterministic relaxation towards potential minimum. Extending this model to inertial dynamics reveals that finite particle mass m acts as a dynamic control parameter capable of strengthening, weakening, constructively inducing, or completely suppressing transport enhancement depending on noise variance. Furthermore, an ultra-minimal model for absolute negative mobility is established in a one-dimensional, purely overdamped system, showing that discontinuous shot noise drives transport opposite to an applied bias without requiring particle inertia, nonlinearity of spatially periodic potential, or explicit time-dependent periodic driving. Conversely, under an alternative scaling of the average stochastic force, an asymmetric distribution of fluctuation amplitudes generates net directed transport through a tilting ratchet effect in the zero-bias limit.
发表机构
- University of Silesia in Katowice（卡托维兹西里西亚大学）
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