Quantum transport in a driven disordered potential: onset of directed current and noise-induced current reversal

TL;DR

This paper investigates how a time-dependent perturbation affects quantum wavepacket transport in a disordered potential, revealing phenomena like directed current and current reversal driven by symmetry violations and inhomogeneous diffusion.

Contribution

It introduces a model of quantum transport with correlated disorder and fluctuating perturbations, demonstrating current reversal mechanisms not previously characterized.

Findings

Time-dependent perturbation induces directed atomic current.

Current reversal occurs after a limited time, influenced by perturbation parameters.

Inhomogeneous diffusion in momentum space underlies current reversal.

Abstract

We study motion of a quantum wavepacket in a one-dimensional potential with correlated disorder. Presence of long-range potential correlations allows for existence of both localized and extended states. Weak time-dependent perturbation in the form of a fluctuating plane wave is superimposed onto the potential. This model can be realized in experiments with optically trapped cold atoms. Time-dependent perturbation causes transitions between localized and extended states. Owing to violation of space-time symmetries, there arises atomic current which is codirectional with the wave-like perturbation. However, it is shown that the perturbation can drag atoms only within some limited time interval, and then the current changes its direction. Increasing of the perturbation bandwidth and/or amplitude results in decreasing of the time of current reversal. We argue that onset of the current reversal is associated with inhomogeneity of diffusion in the momentum space.