Numerical simulation of two-component attractive Fermi gases based on parametrized partition function

TL;DR

This paper extends a parametrized partition function method to simulate the thermodynamics of two-component attractive Fermi gases, revealing fermion pairing phenomena and validating the approach for diverse physical systems.

Contribution

The authors generalize their simulation method to two-component Fermi gases with attractive interactions, enabling accurate thermodynamic analysis despite the fermion sign problem.

Findings

Heat capacity peak indicates fermion pairing below Fermi temperature

High-temperature heat capacity approaches classical value

Method successfully applied to attractive Fermi systems

Abstract

The zero-temperature and finite-temperature thermodynamics of two-component Fermi gases with finite-range attractive interaction suffer from fermion sign problem, which seems like an insurmountable problem in exact numerical simulations. In a recent work, we find a reliable method to simulate the thermodynamic properties of single-component Fermi gases for both noninteracting and repulsively interacting cases based on the method of parametrized partition function and the $\xi_E$ curve of constant energy. In the present work, this method is generalized to two-component Fermi gases with finite-range attractive interaction, which shows clearly that our method has good chance to apply to various Fermi systems. From the simulated heat capacity, we find a peak at the temperature below the Fermi temperature which implies the pairing of fermions with different spin. At high temperature, the simulated heat capacity approaches the classical value. The reasonable result in this work validates the application of our method to attractive cases, which implies a wide range of applications, from nuclear physics, BCS-BEC crossover, superconductivity, to neutron star, etc..