Using Effective Viscosity to Characterize Quantum Turbulence in Superfluids

Characterizing turbulence remains one of the most interesting unsolved problems in physics. By forming tangles of quantized vortices, cold-atom experiments can now be used to study turbulent phenomena. Imaging limitations, however, pose a challenge for experiments: how can one identify turbulent states with available experimental probes? We hypothesize that hydrodynamic shockwaves will provide a way to characterize the nature of the underlying quantum turbulence. In this work we use dynamical simulations to quantify how microscopic quantum turbulence manifests through the emergence of an effective viscosity. We extract the effective viscosity by fitting quantum simulations with classical hydrodynamic models, providing a connection between classical and quantum turbulence. Validating this procedure with cold atoms allows us to construct similar theories for understanding the turbulent structures on large scales, such as might arise in neutron stars.