Interaction and motion of vortices in nonequilibrium quantum fluids

Abstract

We study numerically the motion of vortices in nonequilibrium Bose-Einstein condensates, that are described by a generalized Gross-Pitaevskii equation. We analyze how the vortex properties are modified when moving away under deviation from equilibrium. We find that far from equilibrium, the radial component dominates over the azimuthal one in the distribution of vortex currents at large distances from the vortex core. The modification of the current pattern has a strong effect on the vortex-antivortex interaction energy, that can become entirely repulsive. The vortex trajectories are also strongly affected by the driving and dissipation. Self acceleration of vortices is observed in the strong nonequilibrium case.

Multivortex states and dynamics in nonequilibrium polariton condensates

“…The geometry of the shown vortex configurations is mainly determined by an interplay of the vortex-(anti)vortex repulsive interactions and the repulsion of vortices of both polarities by the sample boundaries. Since the vortex-vortex repulsion is stronger than that for a vortex and antivortex [15], minimization of the energy requires, first of all, maximum possible distances between vortices of the same chirality. The optimal distance between neighboring vortices of opposite chirality appears smaller, because a reduction of the distance between a vortex and an antivortex leads to a more efficient (though, of course, partial) mutual cancelation of their circulating currents.…”

“…7(a)]. At t = 0 the pinning potential is removed and, due to the combined effect of inward currents for the sample boundaries and self-acceleration [15], the vortex starts to move towards the left-hand-side edge of the sample [Figs.7(b) and (c)]. When approaching the edge, the relative velocity of the vortex core with respect to the inward particle flow from the boundary strongly increases, the vortex deforms Fig.7(g)].…”

Topological Defects in Anisotropic Driven Open Systems

“…Consequently, the characteristic KT behavior such as an essential singularity of the correlation length and an universal jump (rounded by finite size) of the superfluid density gives way to novel universal behavior. This prediction could be checked directly in experiments (e.g., with exciton-polaritons, see [18] for relevant parameter regimes) or numerics [37]. The modification of the vortex interaction should also have directly observable effects on phase-ordering kinetics [38][39][40][41], which is an in-teresting problem for further studies.…”

Noise-induced transition from superfluid to vortex state in two-dimensional nonequilibrium polariton condensates

“…For systems that are far from equilibrium, we have shown [18,29] that the gGPE predicts a self-acceleration of vortices and production of new pairs in vortexantivortex collisions, leading to chaotic dynamics. In this parameter regime, we find that a moderate noise suppresses this mechanism, leading to a stabilization of the system.…”