Exotic Vortex States with Discrete Rotational Symmetry in Atomic Fermi Gases with Spin-Orbital-Angular-Momentum Coupling

TL;DR

This paper explores novel vortex states in a spin-orbital-angular-momentum coupled Fermi gas, revealing spontaneous symmetry breaking and unique density patterns that can be observed experimentally.

Contribution

It predicts and characterizes new vortex ground states with discrete rotational symmetry arising from SOAMC in Fermi gases, without external rotation or magnetic fields.

Findings

Discovery of vortex states with discrete rotational symmetry

Spontaneous symmetry breaking in vortex configurations

Numerical verification of predicted vortex structures

Abstract

We investigate the superfluidity of a two-component Fermi gas with spin-orbital-angular-momentum coupling (SOAMC). Due to the intricate interplay of SOAMC, two-photon detuning and atom-atom interaction, a family of vortex ground states emerge in a broad parameter regime of the phase diagram, in contrast to the usual case where an external rotation or magnetic field is generally required. More strikingly, an unprecedented vortex state, which breaks the continuous rotational symmetry to a discrete one spontaneously, is predicted to occur. The underlying physics are elucidated and verified by numerical simulations. The unique density distributions of the predicted vortex states enable a direct observation in experiment.