Fluctuational susceptibility of ultracold bosons in the vicinity of condensation

TL;DR

This paper investigates how fluctuations in ultracold bosonic gases near the Bose-Einstein condensation point lead to a strong divergence in susceptibility, offering new experimental insights into critical phenomena and precise temperature determination.

Contribution

It demonstrates that condensate fluctuations cause a stronger divergence in susceptibility than in superconductors and proposes a method to measure this divergence experimentally.

Findings

Susceptibility diverges with a stronger power-law near $T_c$

Method for measuring fluctuational susceptibility using a magnetic field gradient

Potential for precise determination of the critical temperature

Abstract

We study the behaviour of ultracold bosonic gas in the critical region above the Bose-Einstein condensation in the presence of an artificial magnetic field, $B_\mathrm{art}$. We show that the condensate fluctuations above the critical temperature $T_c$ cause the fluctuational susceptibility, $\chi _\mathrm{fl}$, of a uniform gas to have a stronger power-law divergence than in an analogous superconducting system. Measuring such a divergence opens new ways of exploring critical properties of the ultracold gas and an opportunity of an accurate determination of $T_c$. We describe a method of measuring $\chi _\mathrm{fl}$ which requires a constant gradient in $B_\mathrm{art}$ and suggest a way of creating such a field in experiment.