Influence of the lattice topography on a three-dimensional, controllable Brownian motor

TL;DR

This study explores how lattice topography and directional coupling influence a 3D Brownian motor using cold atoms in a double optical lattice, demonstrating controllable drift directions and speeds through phase adjustments.

Contribution

It experimentally investigates the relation between phase shifts and drift directionality in a 3D Brownian motor, supported by numerical simulations.

Findings

Controllable drift achieved by phase variation in two dimensions.

Drift speed and direction can be finely tuned.

Qualitative agreement between experiments and classical model simulations.

Abstract

We study the influence of the lattice topography and the coupling between motion in different directions, for a three-dimensional Brownian motor based on cold atoms in a double optical lattice. Due to controllable relative spatial phases between the lattices, our Brownian motor can induce drifts in arbitrary directions. Since the lattices couple the different directions, the relation between the phase shifts and the directionality of the induced drift is non trivial. Here is therefore this relation investigated experimentally by systematically varying the relative spatial phase in two dimensions, while monitoring the vertically induced drift and the temperature. A relative spatial phase range of 2pi x 2pi is covered. We show that a drift, controllable both in speed and direction, can be achieved, by varying the phase both parallel and perpendicular to the direction of the measured induced drift. The experimental results are qualitatively reproduced by numerical simulations of a simplified, classical model of the system.