Stability and Anomalous Compressibility of Bose Gases Near Resonance: The scale-dependent interactions and thermal effects

TL;DR

This paper investigates the stability of Bose gases near resonance, revealing how thermal effects and scale-dependent interactions influence compressibility and density profiles, with implications for experimental detection.

Contribution

It introduces a renormalization-based explanation for enhanced stability and anomalous compressibility in Bose gases near resonance, highlighting thermal effects and density profile features.

Findings

Thermal atoms increase repulsiveness of interactions.

Compressibility exhibits anomalous structure near resonance.

Density profile develops a flat top in harmonic traps.

Abstract

The stability of Bose gases near resonance has been a puzzling problem in recent years. In this Letter, we demonstrate that in addition to generating thermal pressure, thermal atoms enhance the repulsiveness of the scale-dependent interactions between condensed atoms due to renormalization effect and further stabilize the Bose gases. Consequently, we find that, as a precursor of instability, the compressibility develops an anomalous structure as a function of scattering length and is drastically reduced compared with the mean-field value. Furthermore, the density profile of a Bose gas in a harmonic trap is found to develop a flat top near the center. This is due to the anomalous behavior of compressibility and can be a potential smoking gun for probing such an effect.