Deterministic ratchet from stationary light fields

TL;DR

This paper demonstrates that stationary optical fields combining conservative and nonconservative forces can induce unidirectional particle transport without external noise or driving, revealing a new class of deterministic ratchets.

Contribution

It introduces a novel method to generate directed particle flow using stationary light fields with combined force components, eliminating the need for external driving or noise.

Findings

Stationary optical lattices can produce unidirectional particle flow.

Both conservative and nonconservative forces are essential for the effect.

Paths converge to limit trajectories flowing in the same direction.

Abstract

Ratchets are dynamic systems where particle transport is induced by zero-average forces due to the interplay between nonlinearity and asymmetry. Generally, they rely on the effect of a strong external driving. We show that stationary optical lattices can be designed to generate particle flow in one direction while requiring neither noise nor driving. Such optical fields must be arranged to yield a combination of conservative (dipole) and nonconservative (radiation pressure) forces. Under strong friction all paths converge to a discrete set of limit periodic trajectories flowing in the same direction.