Behavior of the anomalous correlation function in uniform 2D Bose gas

TL;DR

This paper studies the anomalous correlation function in a 2D Bose gas, revealing its finite value at zero temperature and its significant impact on thermodynamic properties, aligning with recent analytical and numerical results.

Contribution

It provides a detailed analysis of the anomalous correlation function in 2D Bose gases, highlighting its importance at zero temperature and its influence on thermodynamics, using density-phase fluctuation methods.

Findings

Anomalous density remains finite at zero temperature in 2D Bose gases.

Anomalous density significantly affects chemical potential, energy, depletion, and superfluid fraction.

The anomalous correlation function correlates with the true condensate at zero temperature.

Abstract

We investigate the behavior of the anomalous correlation function in two dimensional Bose gas. In the local case, we find that this quantity has a finite value in the limit of weak interactions at zero temperature. The effects of the anomalous density on some thermodynamic quantities are also considered. These effects can modify in particular the chemical potential, the ground sate energy, the depletion and the superfluid fraction. Our predictions are in good agreement with recent analytical and numerical calculations. We show also that the anomalous density presents a significant importance compared to the non-condensed one at zero temperature. The single-particle anomalous correlation function is expressed in two dimensional homogenous Bose gases by using the density-phase fluctuation. We then confirm that the anomalous average accompanies in analogous manner the true condensate at zero temperature while it does not exist at finite temperature.