Equation of state of a Fermi gas in the BEC-BCS crossover: a quantum Monte Carlo study

TL;DR

This study uses quantum Monte Carlo simulations to calculate the equation of state of a two-component Fermi gas across the BEC-BCS crossover, revealing details about molecular regimes and pair correlations.

Contribution

It provides a comprehensive quantum Monte Carlo analysis of the Fermi gas's equation of state across different interaction strengths, including the molecular regime.

Findings

Molecular regime with repulsive interactions for positive scattering length

Dimer-dimer scattering length approximately 0.6 times the atomic scattering length

Detailed pair correlation functions across interaction strengths

Abstract

We calculate the equation of state of a two-component Fermi gas with attractive short-range interspecies interactions using the fixed-node diffusion Monte Carlo method. The interaction strength is varied over a wide range by tuning the value $a$ of the s-wave scattering length of the two-body potential. For $a>0$ and $a$ smaller than the inverse Fermi wavevector our results show a molecular regime with repulsive interactions well described by the dimer-dimer scattering length $a_m=0.6 a$. The pair correlation functions of parallel and opposite spins are also discussed as a function of the interaction strength.