Flux reversal in a two-state symmetric optical thermal ratchet

TL;DR

This paper demonstrates flux reversal in a symmetric two-state optical thermal ratchet using colloidal particles, showing how current direction can be controlled by adjusting state durations, with potential applications in molecular motors.

Contribution

The study provides the first experimental demonstration of flux reversal in a symmetric two-state ratchet system using holographic optical tweezers.

Findings

Flux reversal achieved by changing state durations.

Symmetric potential landscapes can rectify Brownian motion.

Potential applications in designing molecular-scale motors.

Abstract

A Brownian particle's random motions can be rectified by a periodic potential energy landscape that alternates between two states, even if both states are spatially symmetric. If the two states differ only by a discrete translation, the direction of the ratchet-driven current can be reversed by changing their relative durations. We experimentally demonstrate flux reversal in a symmetric two-state ratchet by tracking the motions of colloidal spheres moving through large arrays of discrete potential energy wells created with dynamic holographic optical tweezers. The model's simplicity and high degree of symmetry suggest possible applications in molecular-scale motors.