Rotating quantum turbulence in the unitary Fermi gas

TL;DR

This study investigates quantum turbulence in rotating fermionic superfluids using advanced density functional theory, revealing unique decay modes and the importance of dissipation mechanisms, with implications for modeling neutron star superfluids.

Contribution

First large-scale computational analysis of fermionic quantum turbulence using orbital-based DFT, identifying decay mechanisms and comparing with simpler models.

Findings

Two distinct turbulent decay modes identified.

Orbital-free DFT can qualitatively reproduce decay with dissipation.

Fermionic superfluids exhibit one-body dissipation mechanisms.

Abstract

Quantized vortices carry the angular momentum in rotating superfluids, and are key to the phenomenon of quantum turbulence. Advances in ultra-cold atom technology enable quantum turbulence to be studied in regimes with both experimental and theoretical control, unlike the original contexts of superfluid helium experiments. While much work has been performed with bosonic systems, detailed studies of fermionic quantum turbulence are nascent, despite wide applicability to other contexts such as rotating neutron stars. In this paper, we present the first large-scale study of quantum turbulence in rotating fermionic superfluids using an accurate orbital based time-dependent density functional theory (DFT) called the superfluid local density approximation (SLDA). We identify two different modes of turbulent decay in the dynamical equilibration of a rotating fermionic superfluid, and contrast these results with a computationally simpler orbital-free DFT, which we find can qualitatively reproduce these decay mechanisms if dissipation is explicitly included. These results demonstrate that one-body dissipation mechanisms intrinsic to fermionic superfluids play a key role differentiating fermionic from bosonic turbulence, but also suggest that simpler orbital-free theories may be corrected so that these more efficient techniques can be used to model extended physical systems such as neutron superfluids in neutron stars.