The Fermi-Hubbard model at unitarity

TL;DR

This paper uses advanced Monte Carlo simulations to study the critical temperature and thermodynamics of the dilute attractive Fermi-Hubbard model at unitarity, providing insights relevant for experimental cold atom systems.

Contribution

It introduces a diagrammatic determinant Monte Carlo method with worm updates to accurately simulate the unitarity regime of the Fermi-Hubbard model and determines the universal critical temperature.

Findings

Universal critical temperature T_c/ε_F=0.152(7) at unitarity.

Provides thermodynamic functions for the dilute Fermi gas.

Results aid in thermometry of trapped unitary gases.

Abstract

We simulate the dilute attractive Fermi-Hubbard model in the unitarity regime using a diagrammatic determinant Monte Carlo algorithm with worm-type updates. We obtain the dependence of the critical temperature on the filling factor $\nu$ and, by extrapolating to $\nu \to 0$, determine the universal critical temperature of the continuum unitary Fermi gas in units of Fermi energy: $T_c/\epsilon_F=0.152(7)$. We also determine the thermodynamic functions and show how the Monte Carlo results can be used for accurate thermometry of a trapped unitary gas.