Realization of a feedback controlled flashing ratchet

TL;DR

This paper reports the experimental realization of a feedback-controlled flashing ratchet that significantly increases particle transport speed, compares different feedback algorithms, and suggests improvements for delay tolerance.

Contribution

The study demonstrates an experimental implementation of a feedback ratchet with enhanced particle velocity and compares multiple algorithms for small particle numbers.

Findings

Feedback increases particle velocity by up to tenfold.

Good agreement between experiments and simulations.

Existing algorithms can be optimized for better delay tolerance.

Abstract

A flashing ratchet transports diffusive particles using a time-dependent, asymmetric potential. Particle speed is predicted to increase when a feedback algorithm based on particle positions is used. We have experimentally realized such a feedback ratchet using an optical line trap, and observed that use of feedback increases velocity by up to an order of magnitude. We compare two different feedback algorithms for small particle numbers, and find good agreement with simulations. We also find that existing algorithms can be improved to be more tolerant to feedback delay times.