Decay of a superfluid currents in a moving system of strongly interacting bosons

TL;DR

This paper investigates the stability and decay mechanisms of superfluid currents in strongly interacting bosonic systems on optical lattices, revealing a phase transition and decay processes influenced by quantum and thermal phase slips.

Contribution

It introduces a comprehensive analysis of supercurrent decay, including mean field phase transition and quantum/thermal phase slip effects, across different dimensions.

Findings

Mean field predicts an irreversible dynamic phase transition at a critical phase gradient.

Quantum and thermal phase slips cause current decay below the mean field instability.

Decay rates and transition broadening depend on system dimensionality and temperature.

Abstract

We analyze the stability and decay of supercurrents of strongly interacting bosons on optical lattices. At the mean field level, the system undergoes an irreversible dynamic phase transition, whereby the current decays beyond a critical phase gradient that depends on the interaction strength. At commensurate filling the transition line smoothly interpolates between the classical modulational instability of weakly interacting bosons and the equilibrium Mott transition at zero current. Below the mean field instability, the current can decay due to quantum and thermal phase slips. We derive asymptotic expressions of the decay rate near the critical current. In a three dimensional optical lattice this leads to very weak broadening of the transition. In one and two dimensions the broadening leads to significant current decay well below the mean field critical current. We show that the temperature scale below which quantum phase slips dominate the decay of supercurrents, is easily within experimental reach.