Directed coherent transport due to Bloch oscillation in two dimensions

TL;DR

This paper demonstrates that in two-dimensional systems, Bloch oscillations can lead to a persistent, directed transport of wave packets perpendicular to an external static force, verified through numerical simulations and potential experiments.

Contribution

It reveals that higher-dimensional Bloch oscillations can produce sustained, directed transport, a phenomenon not observed in one-dimensional cases.

Findings

Wave packets drift at a constant velocity perpendicular to the force.

Net transport is always normal to the external force.

Numerical verification and experimental discussion provided.

Abstract

We point out that in higher dimensions, in contrast to the one dimensional case considered usually, Bloch oscillation driven by a static force can induce transport of the wave packet. The wave packet oscillates constantly, but on a larger time scale it drifts at a constant velocity permanently. As a noteworthy feature, the net transport in the long run is always normal to the external force and thus controlled by it. We verify this prediction numerically and discuss its experimental realization both with cold atoms in optical lattices and with two dimensional photonic lattices.