Non-equilibrium work distribution for interacting colloidal particles under friction

TL;DR

This study experimentally examines the non-equilibrium work distribution in a driven colloidal monolayer, revealing Gaussian behavior in static and sliding regimes and non-Gaussian tails during depinning transitions, reflecting complex frictional dynamics.

Contribution

It provides the first experimental analysis of non-equilibrium work distributions in a many-particle colloidal system simulating atomic surface friction.

Findings

Work distribution is Gaussian in static and sliding friction regimes.

Non-Gaussian tails appear during depinning transition.

Shape of work distribution depends on system parameters.

Abstract

We experimentally investigate the distribution of the non-equilibrium work done by an external force on a mesoscopic system with many coupled degrees of freedom: a colloidal monolayer mechanically driven across a periodic light field. Since this system mimics the spatiotemporal dynamics of a crystalline surface moving on a corrugated substrate, our results show general properties of the non-equilibrium work distribution of atomically flat surfaces undergoing friction. We address the role of several parameters which can influence the shape of the work distribution, e.g. the number of particles used to locally probe the system and the time interval to measure the work. We find that, when tuning the control parameters to induce particle depinning from the substrate, there is an abrupt change of the shape of the work distribution. While in the completely static and sliding friction regimes the work distribution is Gaussian, non-Gaussian tails show up due to the spatiotemporal heterogeneity of the particle dynamics during the transition between these two regimes.