Influence of quantum fluctuations on the superfluid critical velocity of a one-dimensional Bose gas
arXiv:1910.12347 · doi:10.1140/epjd/e2020-100532-9
Abstract
The mean-field Gross-Pitaevskii equation with repulsive interactions exhibits frictionless flow when stirred by an obstacle below a critical velocity. Here we go beyond the mean-field approximation to examine the influence of quantum fluctuations on this threshold behaviour in a one-dimensional Bose gas in a ring. Using the truncated Wigner approximation, we perform simulations of ensembles of trajectories where the Bose gas is stirred with a repulsive obstacle below the mean-field critical velocity. We observe the probabilistic formation of grey solitons which subsequently decay, leading to an increase in the momentum of the fluid. The formation of the first soliton leads to a soliton cascade, such that the fluid rapidly accelerates to minimise the speed difference with the obstacle. We measure the initial rate of momentum transfer, and relate it to macroscopic tunnelling between quantised flow states in the ring.
v2: 10 pages, 8 figures. Published version with added references and improvements in response to referees
References in corpus (12)
- Spontaneous vortices in the formation of Bose-Einstein condensates
- Dynamics and statistical mechanics of ultra-cold Bose gases using c-field techniques
- Stationary and non-stationary fluid flow of a Bose-Einstein condensate through a penetrable barrier
- The critical velocity in the BEC-BCS crossover
- Decay of a superfluid currents in a moving system of strongly interacting bosons
- Critical velocity of superfluid flow through single barrier and periodic potentials
- Temperature induced decay of persistent currents in a superfluid ultracold gas
- Perpetual motion and driven dynamics of a mobile impurity in a quantum fluid
- Stochastic phase slips in toroidal Bose-Einstein condensates
- Persistent current of atoms in a ring optical lattice
- Decay of superfluid currents in the interacting one-dimensional Bose gas
- Superfluid critical velocity of an elongated harmonically trapped Bose-Einstein condensate