Approach to nonequilibrium: from anomalous to Brownian diffusion via non-Gaussianity

Fuente: arXiv
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Auteurs principaux: Marchenko, I. G., Marchenko, I. I., Łuczka, J., Spiechowicz, J.
Format: Preprint
Publié: 2025
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author Marchenko, I. G.
Marchenko, I. I.
Łuczka, J.
Spiechowicz, J.
author_facet Marchenko, I. G.
Marchenko, I. I.
Łuczka, J.
Spiechowicz, J.
contents Recent progress in experimental techniques such as single particle tracking allows to analyze both nonequilibrium properties and approach to equilibrium. There are examples showing that processes occurring at finite timescales are distinctly different than their equilibrium counterparts. In this work we analyze a similar problem of approach to nonequilibrium. We consider an archetypal model of nonequilibrium system consisting of a Brownian particle dwelling in a spatially periodic potential and driven by an external time-periodic force. We focus on a diffusion process and monitor its development in time. In the presented parameter regime the excess kurtosis measuring the Gaussianity of the particle displacement distribution evolves in a non-monotonic way: first it is negative (platykurtic form), next it becomes positive (leptokurtic form) and then decays to zero (mesokurtic form). Despite the latter fact diffusion in the long time limit is Brownian, yet non-Gaussian. Moreover, we discover a correlation between non-Gaussianity of the particle displacement distribution and transient anomalous diffusion behavior emerging for finite timescales.
format Preprint
id arxiv_https___arxiv_org_abs_2501_13875
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Approach to nonequilibrium: from anomalous to Brownian diffusion via non-Gaussianity
Marchenko, I. G.
Marchenko, I. I.
Łuczka, J.
Spiechowicz, J.
Statistical Mechanics
Mesoscale and Nanoscale Physics
Soft Condensed Matter
Recent progress in experimental techniques such as single particle tracking allows to analyze both nonequilibrium properties and approach to equilibrium. There are examples showing that processes occurring at finite timescales are distinctly different than their equilibrium counterparts. In this work we analyze a similar problem of approach to nonequilibrium. We consider an archetypal model of nonequilibrium system consisting of a Brownian particle dwelling in a spatially periodic potential and driven by an external time-periodic force. We focus on a diffusion process and monitor its development in time. In the presented parameter regime the excess kurtosis measuring the Gaussianity of the particle displacement distribution evolves in a non-monotonic way: first it is negative (platykurtic form), next it becomes positive (leptokurtic form) and then decays to zero (mesokurtic form). Despite the latter fact diffusion in the long time limit is Brownian, yet non-Gaussian. Moreover, we discover a correlation between non-Gaussianity of the particle displacement distribution and transient anomalous diffusion behavior emerging for finite timescales.
title Approach to nonequilibrium: from anomalous to Brownian diffusion via non-Gaussianity
topic Statistical Mechanics
Mesoscale and Nanoscale Physics
Soft Condensed Matter
url https://arxiv.org/abs/2501.13875