Information geometry and Bose-Einstein condensation

TL;DR

This paper investigates the behavior of information geometry curvature in Bose-Einstein gases at finite particle numbers, showing that it converges to a finite value at phase transition, thus challenging previous conjectures about divergence.

Contribution

It provides a finite-N analysis of IG curvature in Bose-Einstein gases, demonstrating convergence to a finite value at phase transition in the thermodynamic limit.

Findings

Curvature decreases proportionally to a power of N as N increases.

Maximum curvature approaches the critical temperature with increasing N.

Curvature remains finite at phase transition in the thermodynamic limit.

Abstract

It is a long held conjecture in the connection between information geometry (IG) and thermodynamics that the curvature endowed by IG diverges at phase transitions. Recent work on the IG of Bose-Einstein (BE) gases challenged this conjecture by saying that in the limit of fugacity approaching unit -- where BE condensation is expected -- curvature does not diverge, rather it converges to zero. However, as the discontinuous behavior that identify condensation is only observed at the thermodynamic limit, a study of IG curvature at finite number of particles, $N$, is in order from which the thermodynamic behaviour can be observed by taking the thermodynamic limit ($N\to \infty$) posteriorly. This article presents such study, which was made possible by the recent advances presented in [Phys. Rev. A 104, 043318 (2021)]. We find that for a trapped gas, as $N$ increases, the values of curvature decrease proportionally to a power of $N$ while the temperature at which the maximum value of curvature occurs approaches the usually defined critical temperature. This means that, in the thermodynamic limit, curvature has a limited value where a phase transition is observed, contradicting the forementioned conjecture.