Noise-Enabled Optical Ratchets

TL;DR

This paper demonstrates noise-enabled directed transport of microparticles in an optical lattice, showing that controlled noise can induce energy transport, with potential implications for understanding noise-assisted processes in physical systems.

Contribution

First direct observation of noise-assisted transport in a colloidal system using a holographic optical tweezer setup with controlled dynamical disorder.

Findings

Transport occurs within a specific noise frequency range.

Transport direction is controlled by an external force.

Experimental results align with theoretical simulations.

Abstract

In this work we demonstrate single microparticle transport enabled by noise in a one dimensional optical lattice with periodic symmetric potentials and a small constant external force. The one dimensional lattice is implemented by six focused beams with holographic optical tweezers, where a microparticle is trapped in three dimensions. Transport initiates when dynamical disorder is added to the diffracted laser power at each trap ($\pm 30\%$) at a fixed frequency (0 to 35 Hz), while the direction of motion is set by the constant external force. We find that transport is only achieved within a narrow noise frequency range, which is consistent with simulations, and the predicted behavior and observations of noise-induced energy transport in quantum and classical systems. To our knowledge this is the first direct observation of noise-assisted transport in a colloidal system.