Spectral properties and observables in ultracold Fermi gases

TL;DR

This paper develops a non-perturbative spectral functional approach to compute real-time spectral functions of ultracold Fermi gases, providing insights into their thermodynamic and dynamical properties and comparing results with experiments and other theories.

Contribution

It introduces a spectral Dyson-Schwinger equation framework for ultracold Fermi gases, enabling direct real-time calculations of spectral functions and related physical observables.

Findings

Numerical spectral functions for fermions and bosons at unitarity.

Agreement with experimental data and other theoretical approaches.

Potential for calculating transport and spectral properties in superfluid phases.

Abstract

We calculate non-perturbative self-consistent fermionic and bosonic spectral functions of ultra-cold Fermi gases with the spectral functional approach. This approach allows for a direct real-time computation of non-perturbative correlation functions, and in the present work we use spectral Dyson-Schwinger equations. We focus on the normal phase of the spin-balanced Fermi gas and provide numerical results for the full fermionic and bosonic spectral functions. The spectral functions are then used for the determination of the equation of state, the Tan contact and ejection rf spectra at unitarity. These results are compared to experimental data, the self-consistent T-matrix approach and lattice results. Our approach offers a wide range of applications, including the ab initio calculation of transport and spectral properties of the superfluid phase in the BCS-BEC crossover.