Brownian motors

TL;DR

Brownian motors harness non-equilibrium noise and symmetry breaking to control particle transport at micro and nano scales, with applications spanning classical and quantum regimes.

Contribution

This paper reviews the principles, recent developments, and applications of Brownian motors, including experimental implementations and potential quantum extensions.

Findings

Demonstrated a diffusive temperature Brownian motor as a proof-of-principle.

Showcased signal mixing as a simple method to control directed transport.

Outlined potential for quantum Brownian motors and future applications.

Abstract

In systems possessing a spatial or dynamical symmetry breaking thermal Brownian motion combined with unbiased, non-equilibrium noise gives rise to a channelling of chance that can be used to exercise control over systems at the micro- and even on the nano-scale. This theme is known as ``Brownian motor'' concept. The constructive role of (the generally overdamped) Brownian motion is exemplified for a noise-induced transport of particles within various set-ups. We first present the working principles and characteristics with a proof-of-principle device, a diffusive temperature Brownian motor. Next, we consider very recent applications based on the phenomenon of signal mixing. The latter is particularly simple to implement experimentally in order to optimize and selectively control a rich variety of directed transport behaviors. The subtleties and also the potential for Brownian motors operating in the quantum regime are outlined and some state-of-the-art applications, together with future roadways, are presented.