A forced thermal ratchet in a memory heat bath

TL;DR

This paper investigates a non-Markovian thermal ratchet model with a memory-dependent friction kernel, deriving exact probability currents and analyzing how memory effects influence particle flow under external driving forces.

Contribution

It provides an exact expression for probability current in a non-Markovian ratchet with a time-dependent force, highlighting the impact of friction memory on current enhancement.

Findings

Memory effects can enhance particle current compared to Markovian cases.

Exact probability current expressions are derived for non-Markovian dynamics.

External force amplitude and bath temperature influence the flow behavior.

Abstract

The present work studies a non-Markovian forced thermal ratchet model on an asymmetric periodic potential. The Brownian dynamics is described by a generalized Langevin equation with an Ornstein-Uhlenbeck-type friction memory kernel. We show that for the case of a time-dependent driving force, also in the form of an Ornstein-Uhlenbeck-like process, an exact expression of the probability current can be derived. We also obtain the behavior of the particle's average rate of flow as a function of the external amplitude force and of the bath temperature when the driving force behaves as a square wave modulation. All our results are compared with those obtained in the Markovian case and we find, fairly remarkably, that in some cases a friction memory kernel results in an enhancement of the current