title: Direct measurement of long-range third-order coherence in Bose-Einstein condensates.
abstract: A major advance in understanding the behavior of light was to describe the coherence of a light source by using correlation functions that define the spatio-temporal relationship between pairs and larger groups of photons. Correlations are also a fundamental property of matter. We performed simultaneous measurement of the second- and third-order correlation functions for atoms. Atom bunching in the arrival time for pairs and triplets of thermal atoms just above the Bose-Einstein condensation (BEC) temperature was observed. At lower temperatures, we demonstrated conclusively the long-range coherence of the BEC for correlation functions to third order, which supports the prediction that like coherent light, a BEC possesses long-range coherence to all orders.
authors.affiliation: Australian Research Council Centre of Excellence for Quantum Atom Optics, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200, Australia.
authors.forename: S S
authors.initials: SS
authors.lastname: Hodgman
authors.forename: R G
authors.initials: RG
authors.lastname: Dall
authors.forename: A G
authors.initials: AG
authors.lastname: Manning
authors.forename: K G H
authors.initials: KG
authors.lastname: Baldwin
authors.forename: A G
authors.initials: AG
authors.lastname: Truscott