Nonperturbative thermodynamics of an interacting Bose gas

TL;DR

This paper develops a non-perturbative approach to study the thermodynamics of an interacting Bose gas, covering various physical properties across different temperature regimes and near phase transitions.

Contribution

It introduces a non-perturbative flow equation method based on exact functional renormalization for comprehensive phase diagram analysis.

Findings

Computed temperature and density dependence of thermodynamic quantities.

Analyzed the quantum phase transition as temperature approaches zero.

Described universal critical behavior near the phase transition.

Abstract

We discuss the thermodynamics of a non-relativistic gas of bosons with a local repulsive interaction. In particular, we compute the temperature and density dependence of pressure, energy and entropy-density, superfluid and condensate-fraction, correlation length, specific heat, isothermal and adiabatic compressibility and various sound velocities. The T->0 limit approaches the quantum phase transition, while the universal critical behavior of a classical second order phase transition in the O(2) universality class determines the region around the critical temperature. Our non-perturbative flow equations based on exact functional renormalization cover all regions in the phase diagram.