Resonant persistent currents for ultracold bosons on a lattice ring

TL;DR

This paper investigates how a localized barrier affects persistent currents in a one-dimensional bosonic gas on a lattice ring, revealing a resonant behavior at specific barrier strengths and analyzing its robustness at finite temperatures.

Contribution

It introduces a detailed study of resonant persistent currents in lattice bosons with a localized barrier, combining exact diagonalization with an effective single-particle model.

Findings

Persistent currents are suppressed in the Mott insulator phase.

A resonant behavior occurs when barrier strength matches interaction energy.

The resonant effect persists at finite temperatures until currents vanish.

Abstract

We consider a one-dimensional bosonic gas on a ring lattice, in the presence of a localized barrier, and under the effect of an artificial gauge field. By means of exact diagonalization we study the persistent currents at varying interactions and barrier strength, for various values of lattice filling. While generically the persistent currents are strongly suppressed in the Mott insulator phase, they show a resonant behaviour when the barrier strength becomes of the order of the interaction energy. We explain this phenomenon using an effective single-particle model. We show that this effect is robust at finite temperature, up the temperature scale where persistent currents vanish.