Decay of super-currents in condensates in optical lattices

TL;DR

This paper analyzes how superfluid currents in boson lattice systems decay due to quantum tunneling and thermal activation, deriving decay rates near critical currents and discussing experimental implications.

Contribution

It provides asymptotic expressions for decay rates near the critical current in different regimes and explores the dimensional dependence of transition broadening.

Findings

Decay rates derived for deep superfluid phase and near Mott transition

Crossover temperature for quantum decay is experimentally accessible

Transition broadening is more pronounced in lower dimensions

Abstract

In this paper we discuss decay of superfluid currents in boson lattice systems due to quantum tunneling and thermal activation mechanisms. We derive asymptotic expressions for the decay rate near the critical current in two regimes, deep in the superfluid phase and close to the superfluid-Mott insulator transition. The broadening of the transition at the critical current due to these decay mechanisms is more pronounced at lower dimensions. We also find that the crossover temperature below which quantum decay dominates is experimentally accessible in most cases. Finally, we discuss the dynamics of the current decay and point out the difference between low and high currents.