Thermally activated phase slips of one-dimensional Bose gases in shallow optical lattices

摘要

We study the decay of superflow via thermally activated phase slips inone-dimensional Bose gases in a shallow optical lattice. By using the Kramersformula, we numerically calculate the nucleation rate of a thermally activatedphase slip for various values of the filling factor and flow velocity in theabsence of a harmonic trapping potential. Within the local densityapproximation, we derive a formula connecting the phase-slip nucleation ratewith the damping rate of a dipole oscillation of the Bose gas in the presenceof a harmonic trap. We use the derived formula to directly compare our theorywith the recent experiment done by the LENS group [L. Tanzi, et al., Sci. Rep.{\bf 6}, 25965 (2016)]. From the comparison, the observed damping of dipoleoscillations in a weakly correlated and small velocity regime is attributeddominantly to thermally activated phase slips rather than quantum phase slips.