Persistent current of atoms in a ring optical lattice

TL;DR

This paper investigates the persistence of atomic current in a ring optical lattice with weak disorder, revealing that current longevity depends on the initial quasimomentum, with decay occurring at higher values due to spectral properties.

Contribution

It introduces a spectral analysis of atomic current decay in a disordered Bose-Hubbard model using Bogoliubov and random matrix theories.

Findings

Atomic current persists at low quasimomentum.

Current decays exponentially at high quasimomentum.

Spectral analysis explains the decay mechanisms.

Abstract

We consider a small ensemble of Bose atoms in a ring optical lattice with weak disorder. The atoms are assumed to be initially prepared in a superfluid state with non-zero quasimomentum and, hence, may carry matter current. It is found that the atomic current persists in time for a low value of the quasimomentum but decays exponentially for a high (around one quater of the Brillouin zone) quasimomentum. The explanation is given in terms of low- and high-energy spectra of the Bose-Hubbard model, which we describe using the Bogoliubov and random matrix theories, respectively.