Observation of Vinen turbulence during far-from-equilibrium Bose-Einstein condensation

TL;DR

This study demonstrates the observation of Vinen quantum turbulence decay in a homogeneous Bose gas, revealing similarities to superfluid helium despite weak interactions and compressibility.

Contribution

First experimental observation of Vinen turbulence decay in a homogeneous Bose-Einstein condensate, linking quantum turbulence dynamics to superfluid helium behavior.

Findings

Decay of vortex line density matches Vinen turbulence predictions

Large-scale dynamics resemble incompressible hydrodynamics

Decay rate independent of interatomic interaction strength

Abstract

Relaxation of far-from-equilibrium quantum fluids, intimately related to the emergence of long-range order, is theoretically associated with the decay of a turbulent isotropic tangle of vortex lines. We observe and study such decaying quantum turbulence in a homogeneous 3D atomic Bose gas. Using matter-wave techniques to magnify the gas density distribution, and then imaging a thin slice of the magnified cloud, we observe imprints of randomly oriented vortex lines and measure the vortex line-length density $\mathcal{L}$. The observed decay of $\mathcal{L}$ agrees with the prediction for Vinen `ultraquantum' turbulence. Although our weakly interacting gases are highly compressible, their large-scale dynamics are consistent with the behavior of an incompressible hydrodynamic fluid, with the decay of $\mathcal{L}$ not depending on the strength of the interatomic interactions and being similar to that in the strongly interacting superfluid helium.