Measurement of the Spatial Correlation Function of Phase Fluctuating Bose-Einstein Condensates

TL;DR

This paper measures the spatial intensity correlation function of phase fluctuating Bose-Einstein Condensates to determine their phase coherence lengths, confirming theoretical predictions with experimental data.

Contribution

It introduces a method using spatial intensity correlations to measure phase coherence lengths in elongated BECs, linking phase fluctuations to measurable intensity correlations.

Findings

Good agreement with predicted correlation functions

Confirmed the expected coherence length of BECs

Demonstrated a method analogous to stellar interferometry

Abstract

We measure the intensity correlation function of two interfering spatially displaced copies of a phase fluctuating Bose-Einstein Condensate (BEC). It is shown that this corresponds to a measurement of the phase correlation properties of the initial condensate. Analogous to the method used in the stellar interferometer experiment of Hanbury Brown and Twiss, we use spatial intensity correlations to determine the phase coherence lengths of elongated BECs. We find good agreement with our prediction of the correlation function and confirm the expected coherence length.