Reversible Transport of Interacting Brownian Ratchets

TL;DR

This study investigates how interacting Brownian particles in a ratchet potential can reverse their transport direction through parameter changes, with thermal noise and frequency affecting net motion, revealing complex reversible transport behaviors.

Contribution

It introduces a detailed numerical analysis of reversible transport and current reversals in interacting Brownian ratchets under varying conditions, highlighting new mechanisms of control.

Findings

Reversible current sign changes occur with parameter variation.

Thermal noise enables net motion along the gentler potential slope.

High temperature and frequency induce additional current inversion.

Abstract

The transport of interacting Brownian particles in a periodic asymmetric (ratchet) substrate is studied numerically. In a zero-temperature regime, the system behaves as a reversible step motor, undergoing multiple sign reversals of the particle current as any of the following parameters are varied: the pinning potential parameters, the particle occupation number, and the excitation amplitude. The reversals are induced by successive changes in the symmetry of the effective ratchet potential produced by the substrate and the fraction of particles which are effectively pinned. At high temperatures and low frequencies, thermal noise assists delocalization of the pinned particles, rendering the system to recover net motion along the gentler direction of the substrate potential. The joint effect of high temperature and high frequency, on the other hand, induces an additional current inversion, this time favoring motion along the direction where the ratchet potential is steeper. The dependence of these properties on the ratchet parameters and particle density is analyzed in detail.