The true mechanism of spontaneous order from turbulence in two-dimensional superfluid manifolds

Abstract

In a two-dimensional (2D) turbulent fluid containing point-like vortices, Lars Onsager predicted that adding energy to the fluid can lead to the formation of persistent clusters of like-signed vortices, i.e., Onsager vortex (OV) clusters. In the evolution of 2D superfluid turbulence in a uniform disk-shaped Bose-Einstein condensate (BEC), it was discovered that a pair of OV clusters with opposite signs can form without any energy input. This striking spontaneous order was explained as due to a vortex evaporative-heating mechanism, i.e., annihilations of vortex-antivortex pairs which remove the lowest-energy vortices and thereby boost the mean energy per vortex. However, in our search for exotic OV states in a boundaryless 2D spherical BEC, we found that OV clusters never form despite the annihilations of vortex pairs. Our analysis reveals that contrary to the general belief, vortex-pair annihilation emits intense sound waves, which damp the motion of all vortices and hence suppress the formation of OV clusters. We also present unequivocal evidences showing that the true mechanism underlying the observed spontaneous OV state is the escaping of vortices from the BEC boundary. Uncovering this mechanism paves the way for a comprehensive understanding of emergent vortex orders in 2D manifolds of superfluids driven far from equilibrium.

6 pages, 6 figures

References in corpus (5)

• Relaxation of superfluid turbulence in highly oblate Bose-Einstein condensates
• Emergence of order from turbulence in an isolated planar superfluid
• Ultracold atoms confined in rf-induced two-dimensional trapping potentials
• Determination of the effective kinematic viscosity for the decay of quasiclassical turbulence in superfluid ${}^4$He
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Cited by in corpus (13)

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• Shell-shaped atomic gases
• Observation of self-patterned defect formation in atomic superfluids -- from ring dark solitons to vortex dipole necklaces
• Rossby-Haurwitz wave in a rotating bubble-shaped Bose-Einstein condensate
• Hydrodynamics of Quantum Vortices on a Closed Surface
• The Peripheral Vortex Biome of Confined Quantum Fluids and Its Influence on Vortex Pair Annihilation
• Dynamics of Onsager vortex clustering in decaying turbulent polariton quantum fluids
• Axis-symmetric Onsager Clustered States of Point Vortices in a Bounded Domain
• Energy spectra and fluxes of two-dimensional turbulent quantum droplets
• Onsager vortex clusters on a sphere
• Synthetic half-integer magnetic monopole and single-vortex dynamics in spherical Bose-Einstein condensates
• Decay of two-dimensional superfluid turbulence over pinning surface
• Random Splitting of Point Vortex Flows