Non-sinusoidal current and current reversals in a gating ratchet

TL;DR

This paper investigates how Brownian particles in a symmetric potential exhibit non-sinusoidal current behaviors and reversals when driven by multiple harmonic forces, revealing complex dynamics beyond simple sinusoidal responses.

Contribution

It demonstrates the emergence of non-sinusoidal current patterns and reversals in a gating ratchet system driven by multiple harmonics, extending understanding of ratchet dynamics.

Findings

Current exhibits sinusoidal dependence on phase at small amplitudes.

Increasing harmonic amplitudes causes departures from sinusoidal behavior.

Current reversals occur even in overdamped regimes.

Abstract

In this work, the ratchet dynamics of Brownian particles driven by an external sinusoidal (harmonic) force is investigated. The gating ratchet effect is observed when another harmonic is used to modulate the spatially symmetric potential in which the particles move. For small amplitudes of the harmonics, it is shown that the current (average velocity) of particles exhibits a sinusoidal shape as a function of a precise combination of the phases of both harmonics. By increasing the amplitudes of the harmonics beyond the small-limit regime, departures from the sinusoidal behavior are observed and current reversals can also be induced. These current reversals persist even for the overdamped dynamics of the particles.