Coherence-enhanced imaging of a degenerate Bose gas

TL;DR

This paper introduces coherence-enhanced imaging, a novel in situ technique using Raman superradiance to measure spatial coherence and condensate properties in ultracold Bose gases, revealing inhomogeneities and collective effects.

Contribution

The paper presents a new imaging method that directly measures spatial coherence and condensate distribution in ultracold gases using Raman superradiance.

Findings

Measured spatially resolved condensate number and correlation functions.

Observed decay of spin gratings due to collective atom-atom scattering.

Detected spatial inhomogeneities in superradiant Bose gases.

Abstract

We present coherence-enhanced imaging, an in situ technique that uses Raman superradiance to probe the spatial coherence properties of an ultracold gas. Applying this method, we obtain a spatially resolved measurement of the condensate number and more generally, of the first-order spatial correlation function in a gas of $^{87}$Rb atoms. We observe the enhanced decay of propagating spin gratings in high density regions of a Bose condensate, a decay we ascribe to collective, non-linear atom-atom scattering. Further, we directly observe spatial inhomogeneities that arise generally in the course of extended sample superradiance.