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.
Highlights
Many-body physics of strongly interacting ultracold atoms in optical lattices has been actively explored in the recent years1͔
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
In the present work we address this issue by focusing on a problem relevant to recent experiments: the fate of superfluid currents in optical lattices in the strongly interacting regime
Summary
Many-body physics of strongly interacting ultracold atoms in optical lattices has been actively explored in the recent years1͔. Quantum effects of strongly interacting bosons, such as number squeezed states generation2͔ and a quantum phase transition from the superfluid to the Mott insulator3͔, have been observed in agreement with earlier theoretical predictions4,5͔. The ability to continuously vary interaction parameters, coupled to the near perfect isolation of these systems, opens the way to address quantum dynamics far from equilibrium In this context, there exists a purely dynamical phase transition of a condensate of weakly interacting bosons moving in an optical lattice. In the present work we address this issue by focusing on a problem relevant to recent experiments: the fate of superfluid currents in optical lattices in the strongly interacting regime. A shorter discussion of the results presented here can be found in Ref. ͓26͔
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have