Phase fluctuations in anisotropic Bose condensates: from cigars to rings

TL;DR

This paper investigates phase fluctuations in ultra-cold atom condensates confined in ring-shaped traps, identifying conditions for strong fluctuations and discussing experimental detection methods, with implications for understanding quantum and thermal effects.

Contribution

It provides a theoretical analysis of phase-fluctuating regimes in ring-shaped Bose condensates, linking fluctuation conditions to atom number and trap geometry, and explores detection strategies.

Findings

Phase fluctuations depend on atom number and trap size.

Zero temperature phase fluctuations arise from interactions and quantum effects.

Conditions for strong phase fluctuations are derived for both box and ring geometries.

Abstract

We study the phase-fluctuating condensate regime of ultra-cold atoms trapped in a ring-shaped trap geometry, which has been realized in recent experiments. We first consider a simplified box geometry, in which we identify the conditions to create a state that is dominated by thermal phase-fluctuations, and then explore the experimental ring geometry. In both cases we demonstrate that the requirement for strong phase fluctuations can be expressed in terms of the total number of atoms and the geometric length scales of the trap only. For the ring-shaped trap we discuss the zero temperature limit in which a condensate is realized where the phase is fluctuating due to interactions and quantum fluctuations. We also address possible ways of detecting the phase fluctuating regime in ring condensates.