Escape dynamics of active particles in multistable potentials

TL;DR

This study investigates how active particles escape from metastable states in multistable potentials, revealing an optimal correlation time for transition rates and introducing a new experimental platform for non-equilibrium dynamics.

Contribution

The paper presents the first experimental observation of an active turnover in escape rates of active particles, supported by a theoretical model, advancing understanding of non-equilibrium escape dynamics.

Findings

Existence of an optimal correlation time for maximum transition rate

Observation of an active turnover phenomenon

Quantitative agreement with a one-dimensional theoretical model

Abstract

Rare transitions between long-lived metastable states underlie a great variety of physical, chemical and biological processes. Our quantitative understanding of reactive mechanisms has been driven forward by the insights of transition state theory. In particular, the dynamic framework developed by Kramers marks an outstanding milestone for the field. Its predictions, however, do not apply to systems driven by non-conservative forces or correlated noise histories. An important class of such systems are active particles, prominent in both biology and nanotechnology. Here, we trap a silica nanoparticle in a bistable potential. To emulate an active particle, we subject the particle to an engineered external force that mimics self-propulsion. We investigate the active particle's transition rate between metastable states as a function of friction and correlation time of the active force. Our experiments reveal the existence of an optimal correlation time where the transition rate is maximized. This novel \emph{active turnover} is reminiscent of the much celebrated Kramers turnover despite its fundamentally different origin. Our observations are quantitatively supported by a theoretical analysis of a one-dimensional model. Besides providing a deeper understanding of the escape dynamics of active particles in multistable potentials, our work establishes a new, versatile experimental platform to study particle dynamics in non-equilibrium settings.