Supercurrent decay in one-dimensional Bose gases in a ring optical lattice

Applying the time-evolving block decimation method to the Bose-Hubbard model with a periodic boundary condition, we study the decay dynamics of supercurrents in one-dimensional lattice bosons. We show that while a supercurrent persists when the ratio of the onsite interacton U to the hopping J is sufficiently small, increasing U/J enhances quantum fluctuations and causes the decay of the supercurrent. In the case of commensurate filling, we find a coherent oscillation between certain momenta p and -p resulting from the decay instead of the relaxation to a zero momentum state. We also find that the double-phase slip, in which the winding number of the supercurrent suddenly changes from 1 to -1, occurs associated with this oscillation.