Directed Transport of Confined Brownian Particles with Torque

TL;DR

This paper explores how an external magnetic field and nonthermal fluctuations induce directed transport in confined Brownian particles, revealing a ratchet mechanism driven by symmetry breaking in a nonequilibrium setting.

Contribution

It demonstrates that nonthermal Ornstein-Uhlenbeck fluctuations combined with torque can produce directed transport, highlighting a novel ratchet mechanism in confined Brownian systems.

Findings

Directed transport emerges under nonthermal fluctuations and torque.

Transport depends on correlation time, torque, and channel geometry.

Symmetry breaking explains the ratchet mechanism.

Abstract

We investigate the influence of an external magnetic field (torque) on the motion of Brownian particles confined in a channel geometry with varying width. Furthermore, the particles are driven by random fluctuations modeled by the Ornstein-Uhlenbeck process (OUP) with given correlation time $\tau_c$. The latter is implemented as both a thermal and a nonthermal process. In contrast to the thermal OUP for the nonthermal process directed transport emerges, i.e. our setup now realizes a ratchet mechanism: Due to the assumed thermodynamic nonequilibrium situation random fluctuations are rectified. The transport quantities of the system are studied in detail with respect to the correlation time, the torque and the channel geometry. Eventually, the mechanism of the symmetry breaking is elucidated.