Ground state of a homogeneous Bose gas: a diffusion Monte Carlo calculation

TL;DR

This paper employs diffusion Monte Carlo simulations to accurately determine the ground state energy of a homogeneous Bose gas, confirming universal behavior at low densities and highlighting the significance of beyond-mean-field effects at experimental densities.

Contribution

It introduces a diffusion Monte Carlo approach to compute the ground state of a Bose gas with various interactions, emphasizing the importance of corrections beyond mean-field theory in realistic conditions.

Findings

Energy per particle follows universal behavior at low density

Corrections to mean-field energies are significant at experimental densities

Potential details have minimal impact at low densities

Abstract

We use a diffusion Monte Carlo method to calculate the lowest energy state of a uniform gas of bosons interacting through different model potentials, both strictly repulsive and with an attractive well. We explicitly verify that at low density the energy per particle follows a universal behavior fixed by the gas parameter na^3. In the regime of densities typical for experiments in trapped Bose-condensed gases, the corrections to the mean-field energies greatly exceed the differences due to the details of the potential.