Decaying quantum turbulence during far-from-equilibrium Bose--Einstein condensation

We study the dynamics of vortex lines during far-from-equilibrium Bose--Einstein condensation. Using matter-wave techniques to magnify the density distribution and then imaging just a cross section of the magnified cloud allows us to directly reveal randomly oriented and bending vortex lines embedded in the 3D cloud. We extract the vortex line length density $\mathcal{L}$ using persistent homology, and find that it decays according to the prediction for Vinen turbulence, ${\rm d}\mathcal{L}/{\rm d}t \propto -\mathcal{L}^2$, and that the prefactor does not depend on the strength of the interparticle interactions.