Depinning transition of self-propelled particles

TL;DR

This paper investigates how self-propulsion and active noise influence the depinning transition of colloidal particles from a landscape, revealing different critical behaviors and diffusion phenomena depending on particle reorientation speed.

Contribution

It introduces a detailed analysis of how active noise affects depinning transitions, highlighting the dependence on reorientation speed and dimensionality, and extends to systems with saddle-node bifurcations.

Findings

Drift velocity exhibits critical exponent 1/2 for quickly reorienting particles.

Drift velocity scales as $d/2$ for slow reorienting particles.

Different giant diffusion phenomena occur in the two regimes.

Abstract

Depinning transitions occur when a threshold force must be applied to drive an otherwise immobile system. For the depinning of colloidal particles from a corrugated landscape, we show how active noise due to self-propulsion impacts the nature of this transition, depending on the speed and the dimensionality $d$ of rotational Brownian motion: the drift velocity exhibits the critical exponent 1/2 for quickly reorienting particles, which changes to $d/2$ for slow ones; in between these limits, the drift varies superexponentially. Different giant diffusion phenomena emerge in the two regimes. Our predictions extend to systems with a saddle-node bifurcation in the presence of a bounded noise. Moreover, our findings suggest that nonlinear responses are a sensitive probe of nonequilibrium behavior in active matter.