Quantum Monte Carlo simulation of a two-dimensional Bose gas

TL;DR

This paper uses quantum Monte Carlo simulations to study the properties and stability of a two-dimensional Bose gas across different interaction regimes, providing insights into its equation of state, condensate fraction, and critical density for instability.

Contribution

It presents the first comprehensive quantum Monte Carlo analysis of a 2D Bose gas with various interatomic potentials, including stability criteria at large scattering lengths.

Findings

Universal behavior at low densities confirmed

Condensate fraction decreases with increasing gas parameter

Critical density for instability identified

Abstract

The equation of state of a homogeneous two-dimensional Bose gas is calculated using quantum Monte Carlo methods. The low-density universal behavior is investigated using different interatomic model potentials, both finite-ranged and strictly repulsive and zero-ranged supporting a bound state. The condensate fraction and the pair distribution function are calculated as a function of the gas parameter, ranging from the dilute to the strongly correlated regime. In the case of the zero-range pseudopotential we discuss the stability of the gas-like state for large values of the two-dimensional scattering length, and we calculate the critical density where the system becomes unstable against cluster formation.