Hanbury Brown and Twiss correlations across the Bose–Einstein condensation threshold

Hanbury Brown and Twiss correlations--correlations in far-field intensity fluctuations--yield fundamental information on the quantum statistics of light sources, as demonstrated after the discovery of photon bunching1, 2, 3. Drawing on the analogy between photons and atoms, similar measurements have...

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Bibliographic Details
Published in:	Nature physics 2012-03, Vol.8 (3), p.195-198
Main Authors:	Perrin, A., Bücker, R., Manz, S., Betz, T., Koller, C., Plisson, T., Schumm, T., Schmiedmayer, J.
Format:	Article
Language:	eng
Subjects:	Analogies Atoms & subatomic particles Coherence Condensing Correlation Density Fluctuation Photons Quantum physics Thresholds
Online Access:	Get full text
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Summary:	Hanbury Brown and Twiss correlations--correlations in far-field intensity fluctuations--yield fundamental information on the quantum statistics of light sources, as demonstrated after the discovery of photon bunching1, 2, 3. Drawing on the analogy between photons and atoms, similar measurements have been performed for matter-wave sources, probing density fluctuations of expanding ultracold Bose gases4, 5, 6, 7, 8. Here we use two-point density correlations to study how coherence is gradually established when crossing the Bose-Einstein condensation threshold. Our experiments reveal a persistent multimode character of the emerging matter-wave as seen in the non-trivial spatial shape of the correlation functions for all probed source geometries, from nearly isotropic to quasi-one-dimensional, and for all probed temperatures. The qualitative features of our observations are captured by ideal Bose gas theory9, whereas the quantitative differences illustrate the role of particle interactions. [PUBLICATION ABSTRACT]
ISSN:	1745-2473 1745-2481