Superfluid-insulator transition in a moving system of interacting bosons

TL;DR

This paper investigates the stability of superfluid currents in strongly interacting cold atom systems, revealing a phase transition influenced by interactions and dimensionality, with implications for experimental observations.

Contribution

It introduces a comprehensive analysis of the superfluid-insulator transition in moving interacting bosons, connecting classical and quantum phase transitions and considering fluctuation effects.

Findings

Critical phase gradient depends on interaction strength.

Transition boundary interpolates between classical and quantum limits.

Quantum fluctuations smear the transition in low dimensions.

Abstract

We analyze stability of superfluid currents in a system of strongly interacting ultra-cold atoms in an optical lattice. We show that such a system undergoes a dynamic, irreversible phase transition at a critical phase gradient that depends on the interaction strength between atoms. At commensurate filling, the phase boundary continuously interpolates between the classical modulation instability of a weakly interacting condensate and the equilibrium quantum phase transition into a Mott insulator state at which the critical current vanishes. We argue that quantum fluctuations smear the transition boundary in low dimensional systems. Finally we discuss the implications to realistic experiments.