Time-dependent currents of 1D bosons in an optical lattice

TL;DR

This paper investigates the dynamics of currents in a one-dimensional Bose gas within an optical lattice, revealing a broad crossover influenced by acceleration and interactions, with implications for experimental measurements and theoretical models.

Contribution

It introduces a numerical analysis of current stability and decay in 1D Bose gases using TEBD, highlighting differences from higher-dimensional mean-field predictions.

Findings

Identification of a broad crossover in current stability as a function of acceleration and interactions.

Quantitative predictions for time-dependent current decay rates.

Agreement with phase-slip scaling at higher densities, deviations near unit filling.

Abstract

We analyse the time-dependence of currents in a 1D Bose gas in an optical lattice. For a 1D system, the stability of currents induced by accelerating the lattice exhibits a broad crossover as a function of the magnitude of the acceleration, and the strength of the inter-particle interactions. This differs markedly from mean-field results in higher dimensions. Using the infinite Time Evolving Block Decimation algorithm, we characterise this crossover by making quantitative predictions for the time-dependent behaviour of the currents and their decay rate. We also compute the time-dependence of quasi-condensate fractions which can be measured directly in experiments. We compare our results to calculations based on phase-slip methods, finding agreement with the scaling as the particle density increases, but with significant deviations near unit filling.