Quantum Degenerate Fermi Gas with Spin-orbit Coupling and Crossed Zeeman Fields

TL;DR

This paper investigates how artificial spin-orbit coupling and crossed Zeeman fields affect the properties of quantum degenerate Fermi gases, revealing parity violation impacts on spectroscopic, thermodynamic, and superfluid characteristics.

Contribution

It provides a detailed analysis of parity violation effects on excitation spectra, thermodynamics, and pairing in spin-orbit coupled Fermi gases, including the influence on superfluid transition temperature.

Findings

Parity violation leads to anisotropic thermodynamic properties.

Pairing temperature decreases significantly with stronger parity violation.

The superfluid order parameter becomes parity-violating under crossed Zeeman fields.

Abstract

We study quantum degenerate ultra-cold Fermi gases in the presence of artificial spin-orbit coupling and crossed Zeeman fields. We emphasize the case where parity is violated in the excitation spectrum and compare it with the simpler situation where parity is preserved. We investigate in detail spectroscopic properties such as the excitation spectrum, the spectral function, momentum distribution and density of states for the cases where parity is preserved or violated. Similarly, we show that thermodynamic properties such as pressure, chemical potential, entropy, specific heat, isothermal compressibility and induced spin polarization become anisotropic as a function of Zeeman field components, when parity is violated. Lastly, we discuss the effects of interactions and present results for the pairing temperature as the precursor for the transition to a superfluid state. In particular, we find that the pairing temperature is dramatically reduced in the weak interaction regime as parity violation gets stronger, and that the momentum dependence of the order parameter for superfluidity violates parity when crossed Zeeman fields are present for finite spin-orbit coupling.