Regensburg 2025 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 4: Focus Session: Nonlinear Dynamics and Stochastic Processes – Advances in Theory and Applications I
DY 4.9: Vortrag
Montag, 17. März 2025, 12:15–12:30, H43
Memory effects and non-linear responses in colloidal depinning — Arthur V. Straube1,2 and •Felix Höfling2,1 — 1Zuse-Institut Berlin — 2Institut für Mathematik, Freie Universität Berlin
Particle transport in inhomogeneous environments is complex and typically exhibits non-Markovian responses. The latter can be quantified by a memory function within the framework of the linear generalised Langevin equation (GLE). Here, we exemplify the implications of steady driving on the memory of a colloidal model system for Brownian motion in a corrugated potential landscape, a prototypical set-up to study depinning and non-linear responses far from equilibrium [1,2]. Relying on exact solutions of the model, we show that the random force entering the GLE displays a bias far from equilibrium, which corroborates a recent more general prediction. Based on Brownian dynamics simulations, we show that already moderate driving accelerates the decay of the memory function by several orders of magnitude in time. Moreover in equilibrium, the memory persists much longer than suggested by the timescales of the mean-square displacement. Furthermore, the memory function changes from a monotonic decay to non-monotonic, damped oscillations, which can be understood from a competition of confined motion and depinning. The simulated transport process also is pronouncedly non-Gaussian, which questions the usual Gaussian approximation of the random force in the GLE.
[1] A. V. Straube & F. Höfling, J. Phys. A 57, 295003 (2024).
[2] A. V. Straube & F. Höfling, Phys. Rev. E 110, L06260x (2024).
Keywords: depinning transition; non-Markovian dynamics; non-linear response; non-equilibrium processes