Enslaving random fluctuations in nonequlibrium systems

TL;DR

This paper demonstrates that unidirectional motion in inhomogeneous systems can be achieved with symmetric potentials and white noise, by altering local stability through spatial variations in temperature or friction.

Contribution

It introduces new models showing unidirectional motion in symmetric potentials due to inhomogeneity, expanding understanding beyond ratchet mechanisms.

Findings

Unidirectional motion occurs in symmetric potentials with inhomogeneity.

Temperature and friction variations alter local stability of states.

Models work under the principle of stability alteration due to inhomogeneity.

Abstract

Several physical models have recently been proposed to obtain unidirectional motion of an overdamped Brownian particle in a periodic potential system. The asymmetric ratchetlike form of the periodic potential and the presence of correlated nonequilibrium fluctuating forces are considered essential to obtain such a macroscopic motion in homogeneous systems. In the present work, instead, inhomogeneous systems are considered, wherein the friction coefficient and/or temperature could vary in space. We show that unidirectional motion can be obtained even in a symmetric nonratchetlike periodic potential system in the presence of white noise fluctuations. We consider four different cases of system inhomogeneity We argue that all these different models work under the same basic principle of alteration of relative stability of otherwise locally stable states in the presence of temperature inhomogeneity.