Suppressed solitonic cascade in spin-imbalanced superfluid Fermi gas

TL;DR

This paper investigates how spin polarization in superfluid Fermi gases alters the decay cascades of topological defects, revealing suppression of vortex reconnections and potential impacts on quantum turbulence.

Contribution

The study introduces a microscopic approach showing that spin imbalance dramatically modifies defect decay cascades in superfluid Fermi gases, a phenomenon not observed in Bose systems.

Findings

Decay cascades end at different stages depending on polarization

Unpaired particles are sucked into soliton structures

Vortex reconnections are hindered by polarization effects

Abstract

Cold atoms experiments offer invaluable information on superfluid dynamics, including decay cascades of topological defects. While the cascade properties are well established for Bose systems, our understanding of their behavior in Fermi counterparts is very limited, in particular in spin-imbalanced systems, where superfluid (paired) and normal (unpaired) particles naturally coexist giving rise to complex spatial structure of the atomic cloud. Here we show, based on a newly developed microscopic approach, that the decay cascades of topological defects are dramatically modified by the spin-polarization. We demonstrate that decay cascades end up at different stages: "dark soliton", "vortex ring" or "vortex line", depending on the polarization. We reveal that it is caused by sucking of unpaired particles into the soliton's internal structure. As a consequence vortex reconnections are hindered and we anticipate that quantum turbulence phenomenon can be significantly affected, indicating new physics induced by polarization effects.