Non-Hermitian topological superfluidity in a three-dimensional fermi gas with spin-orbit coupling

TL;DR

This paper explores how non-Hermitian effects, spin-orbit coupling, and dissipation influence superfluidity and topological phases in a three-dimensional Fermi gas, revealing phase transitions and topological states driven by these factors.

Contribution

It introduces a non-Hermitian mean field framework to analyze the phase diagram of a spin-orbit coupled Fermi gas with complex interactions, highlighting dissipation-induced phase transitions and topological superfluidity.

Findings

Dissipation induces a phase transition from superfluid to normal phase.

Weak interactions cause reentrance of superfluidity under dissipation.

Spin-orbit coupling expands the regimes of superfluid and normal phases.

Abstract

The experimental advances in realizing artificial spin-orbit coupling (SOC) and non-Hermitian potentials in ultracold atomic system open a new avenue for exploring their significant roles in quantum many-body physics. Here, we investigate a non-Hermitian, two-component Fermi system in a cubic lattice with Rashba SOC and complex-valued interaction arising from two-body loss. We adopt the non-Hermitian mean field theory and map out the phase diagram at zero temperature. The interplay of dissipation and on-site interaction drives a dissipation-induced phase transition from superfluid (SF) to normal phase (N). Notably, for weak interaction strengths, this leads to a reentrance of the superfluid state. The presence of SOC significantly expands the parameter regime for both the normal phase and the metastable superfluid phase(MSF). Whereas, the Zeeman field can drive the system from a conventional superfluid into a topological superfluid phase(TSF), characterized by a nontrivial topological invariant. These results enrich our knowledge of pairing superfluidity in Fermi systems.