Metastable states and macroscopic quantum tunneling in a cold atom Josephson ring

TL;DR

This paper investigates the macroscopic quantum phenomena in a cold atom Josephson ring, identifying metastable states and tunneling rates, with potential experimental detection via time-of-flight imaging.

Contribution

It derives an effective low energy theory for cold atom Josephson rings and analyzes metastable states and quantum tunneling effects, which are experimentally observable.

Findings

Existence of metastable current-carrying states

Quantification of transition rates due to quantum tunneling

Predictions for experimental signatures in time-of-flight images

Abstract

We study macroscopic properties of a system of weakly interacting neutral bosons confined in a ring-shaped potential with a Josephson junction. We derive an effective low energy action for this system and evaluate its properties. In particular we find that the system possesses a set of metastable current-carrying states and evaluate the rates of transitions between these states due to macroscopic quantum tunneling. Finally we discuss signatures of different metastable states in the time-of-flight images and argue that the effect is observable within currently available experimental technique.