Relaxation of superfluid turbulence in highly oblate Bose-Einstein condensates
Woo Jin Kwon, Geol Moon, Jae-yoon Choi +2 more
We investigate thermal relaxation of superfluid turbulence in a highly oblate Bose-Einstein condensate. We generate turbulent flow in the condensate by sweeping the center region of the condensate with a repulsive optical potential. The turbulent condensate shows a spatially disordered distribution of quantized vortices, and the vortex number of the condensate exhibits nonexponential decay behavior which we attribute to the vortex pair annihilation. The vortex-antivortex collisions in the condensate are identified with crescent-shaped, coalesced vortex cores. We observe that the nonexponential decay of the vortex number is quantitatively well described by a rate equation consisting of one-body and two-body decay terms. In our measurement, we find that the local two-body decay rate is closely proportional to ${T}^{2}/\ensuremath{\mu}$, where $T$ is the temperature and $\ensuremath{\mu}$ is the chemical potential.
arXiv:1403.4658•Physical Review A•Dec 19, 2014•155 citations