Controlling Transport of Ultra-Cold Atoms in 1D Optical Lattices with Artificial Gauge Fields

TL;DR

This paper demonstrates how artificial gauge fields in optical lattices can induce controllable quantum transport of ultra-cold fermions, with potential experimental observability, while bosons do not support such transport under the same conditions.

Contribution

It introduces a method to control quantum transport in optical lattices using complex tunneling phases, revealing the role of gauge fields in non-interacting fermion dynamics.

Findings

Finite quasi steady-state current (QSSC) can be induced by ramping the phase of tunneling.

The current's direction and magnitude are controllable via phase difference.

Entanglement entropy remains unchanged during QSSC.

Abstract

We show that the recently developed optical lattices with Peierls substitution -- which can be modeled as a lattice with a complex tunneling coefficient -- may be used to induce controllable quantum transport of ultra-cold atoms. In particular, we show that by ramping up the phase of the complex tunneling coefficient in a spatially uniform fashion, a finite quasi steady-state current (QSSC) ensues from the exact dynamics of non-interacting fermions. The direction and magnitude of the current can be controlled by the overall phase difference but not the details of the ramp. The entanglement entropy does not increase when the QSSC lasts. Due to different spin statistics, condensed non-interacting bosons do not support a finite QSSC under the same setup. We also find that an approximate form of the QSSC survives when perturbative effects from interactions, weak harmonic background traps, and finite-temperature are present, which suggests that our findings should be observable with available experimental capabilities.