Monte Carlo calculations for Fermi gases in the unitary limit with a zero-range interaction

TL;DR

This paper introduces a Monte Carlo method that directly models zero-range interactions in ultracold Fermi gases at unitarity, avoiding the need for extrapolation from finite-range potentials.

Contribution

The authors develop a quantum Monte Carlo approach that explicitly incorporates zero-range interactions with proper boundary conditions, improving accuracy and reliability.

Findings

Results show low variance and high reliability of the method.

Direct zero-range calculations match or improve upon previous extrapolated results.

Method enables more precise studies of strongly interacting Fermi gases.

Abstract

An ultracold Fermi gas with a zero-range attractive potential in the unitary limit is investigated using variational and diffusion Monte Carlo methods. Previous calculations have used a finite range interactions and extrapolate the results to zero-range. Here we extend the quantum Monte Carlo method to directly use a zero-range interaction without extrapolation. We employ a trial wave function with the correct boundary conditions, and modify the sampling procedures to handle the zero-range interaction. The results are reliable and have low variance.