Vortex Reconnections and Rebounds in Trapped Atomic Bose-Einstein Condensates

Abstract

Reconnections and interactions of filamentary coherent structures play a fundamental role in the dynamics of fluids, redistributing energy and helicity among the length scales and inducing fine-scale turbulent mixing. Unlike ordinary fluids, where vorticity is a continuous field, in quantum fluids vorticity is concentrated into discrete (quantized) vortex lines turning vortex reconnections into isolated events, making it conceptually easier to study. Here we report experimental and numerical observations of three-dimensional quantum vortex interactions in a cigar-shaped atomic Bose-Einstein Condensate. In addition to standard reconnections, already numerically and experimentally observed in homogeneous systems away from boundaries, we show that double reconnections, rebounds and ejections can also occur as a consequence of the non-homogeneous, confined nature of the system.

Vortex mass in a superfluid

“…When the quantised vortex is perturbed by kelvons by sufficiently large amplitude the vortex core is displaced from and orbits on a circular path around its own equilibrium position with angular frequency ω k [33]. Evidence for the existence of kelvons with great wave numbers on quantised vortices have been obtained via direct imaging in superfluid helium [34] and in atomic Bose-Einstein condensates [35,36].…”

Critical angular velocity for vortex lines formation

“…Presumably, it will be more easy to observe the consequences of the counter-rotating flow, like for instance the nontrivial temperature dependence of Ω 0 (T ) or the presence of the latent heat for the vortex formation. The new technological developments [42] in the study of cold atoms condensates will probably permit to measure some of the effects of the anti-correlation between the velocities of the superfluid and normal components. In the case of cold atoms condensates, the complete control on the boundary conditions for the viscous component of the fluid is crucial to test the mechanism discussed in this article.…”

Chaotic few-body vortex dynamics in rotating Bose-Einstein condensates

“…Vortex turbulence in two-dimensional BECs has become a subject of increasing experimental interest, due to the controllable nature of BECs and quantum vortices. Experimental techniques have advanced, resulting in accessible methods to detect vortex circulation [18], image vortices in-situ [19], and build a picture of vortex dynamics at different times in a single experiment [20,21]. Recent times have seen experiments exhibiting the von Kármán vortex street [22], as well as investigations into decaying two dimensional turbulence [23,24] and demonstration of Onsager vortex clusters [25,26] in Bose-Einstein condensates.…”