Fluctuation susceptibility of ultracold bosons in the vicinity of condensation in the presence of an artificial magnetic field.

We study the behavior of ultracold bosonic gases in the critical region above the Bose-Einstein condensation in the presence of an artificial magnetic field, Bart. We show that the condensate fluctuations above the critical temperature Tc cause the fluctuational susceptibility, χfl, 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 ultracold gases and an opportunity for an accurate determination of Tc. We describe a method of measuring χfl which requires a constant gradient in Bart and suggest a way of creating such a field in experiment. [ABSTRACT FROM AUTHOR]