Quantifying Finite Temperature Effects in Atom Chip Interferometry of Bose-Einstein Condensates

TL;DR

This paper investigates how finite temperature influences phase fluctuations and vortex formation in Bose-Einstein condensate interferometry on atom chips, proposing a method to observe vortices for enhanced measurement precision.

Contribution

It provides a detailed analysis of temperature-dependent phase fluctuations and vortex dynamics, introducing a technique to directly observe vortex formation in BEC interferometry.

Findings

Small phase fluctuations at low temperatures due to mean-field depletion

Resonant vortex production when clouds are initially anti-phase

Thermal occupation of Bogoliubov modes causes smooth vortex formation transition

Abstract

We quantify the effect of phase fluctuations on atom chip interferometry of Bose-Einstein condensates. At very low temperatures, we observe small phase fluctuations, created by mean-field depletion, and a resonant production of vortices when the two clouds are initially in anti-phase. At higher temperatures, we show that the thermal occupation of Bogoliubov modes makes vortex production vary smoothly with the initial relative phase difference between the two atom clouds. We also propose a technique to observe vortex formation directly by creating a weak link between the two clouds. The position and direction of circulation of the vortices is subsequently revealed by kinks in the interference fringes produced when the two clouds expand into one another. This procedure may be exploited for precise force measurement or motion detection.