Two-dimensional rocking ratchet for cold atoms

TL;DR

This paper experimentally demonstrates a two-dimensional rocking ratchet with cold atoms, showing unique rectification effects and controllable current directions using phase-modulated optical lattices and harmonic drivings.

Contribution

It provides the first experimental realization of a 2D rocking ratchet with cold atoms, confirming theoretical predictions and enabling directional control of atomic currents.

Findings

Observation of a unique rectification phenomenon in 2D ratchets

Demonstration of controllable atomic current direction within the lattice plane

Validation of theoretical predictions for high-dimensional rocking ratchets

Abstract

We investigate experimentally a two-dimensional rocking ratchet for cold atoms, realized by using a driven three-beam dissipative optical lattice. AC forces are applied in perpendicular directions by phase-modulating two of the lattice beams. As predicted by the general theory [S. Denisov et al., Phys. Rev. Lett. 100, 224102 (2008)], we observe a rectification phenomenon unique to high-dimensional rocking ratchets, as determined by two single-harmonic drivings applied in orthogonal directions. Also, by applying two bi-harmonic forces in perpendicular directions, we demonstrate the possibility of generating a current in an arbitrary direction within the optical lattice plane.