Momentum distribution in the unitary Bose gas from first principles

TL;DR

This paper uses quantum Monte Carlo methods to analyze the momentum distribution and critical temperature of a unitary Bose gas, revealing universal behaviors and comparing with experimental data, while considering effects of three-body interactions.

Contribution

First-principles quantum Monte Carlo study of a realistic unitary Bose gas, providing detailed momentum distribution and critical temperature insights.

Findings

Critical temperature is lower than ideal Bose gas predictions.

Full momentum distribution including universal asymptotics is determined.

Model's observables are weakly affected by the three-body length scale.

Abstract

We consider a realistic bosonic N-particle model with unitary interactions relevant for Efimov physics. Using quantum Monte Carlo methods, we find that the critical temperature for Bose-Einstein condensation is decreased with respect to the ideal Bose gas. We also determine the full momentum distribution of the gas, including its universal asymptotic behavior, and compare this crucial observable to recent experimental data. Similar to the experiments with different atomic species, differentiated solely by a three-body length scale, our model only depends on a single parameter. We establish a weak influence of this parameter on physical observables. In current experiments, the thermodynamic instability of our model from the atomic gas towards an Efimov liquid could be masked by the dynamical instability due to three-body losses.