Characteristics of Two-Dimensional Quantum Turbulence in a Compressible Superfluid

TL;DR

This study investigates two-dimensional quantum turbulence in a Bose-Einstein condensate, revealing vortex clustering, energy spectra, and flow evolution, highlighting complex behaviors unique to compressible superfluids.

Contribution

It provides experimental and numerical insights into vortex dynamics, energy spectra, and flow evolution in 2D quantum turbulence within a Bose-Einstein condensate.

Findings

Disordered vortex distribution evolves into persistent currents.

Vortex clustering of same circulation observed.

Energy spectrum follows $k^{-5/3}$ at low k and $k^{-3}$ at high k.

Abstract

Under suitable forcing a fluid exhibits turbulence, with characteristics strongly affected by the fluid's confining geometry. Here we study two-dimensional quantum turbulence in a highly oblate Bose-Einstein condensate in an annular trap. As a compressible quantum fluid, this system affords a rich phenomenology, allowing coupling between vortex and acoustic energy. Small-scale stirring generates an experimentally observed disordered vortex distribution that evolves into large-scale flow in the form of a persistent current. Numerical simulation of the experiment reveals additional characteristics of two-dimensional quantum turbulence: spontaneous clustering of same-circulation vortices, and an incompressible energy spectrum with $k^{-5/3}$ dependence for low wavenumbers $k$ and $k^{-3}$ dependence for high $k$.