title: Probing the quantum state of a guided atom laser pulse.
abstract: We describe bichromatic superradiant pump-probe spectroscopy as a tomographic probe of the Wigner function of a dispersing particle beam. We employed this technique to characterize the quantum state of an ultracold atomic beam, derived from a 87Rb Bose-Einstein condensate, as it propagated in a 2.5 mm diameter circular waveguide. Our measurements place an upper bound on the longitudinal phase space area occupied by the 3 x 10(5) atom beam of 9(1)Planck's constant and a lower bound on the coherence length of L>or=13(1) microm. These results are consistent with full quantum degeneracy after multiple orbits around the waveguide.
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720, USA. klmoore@berkeley.edu
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Moore
authors.forename: Subhadeep
authors.initials: S
authors.lastname: Gupta
authors.forename: Kater W
authors.initials: KW
authors.lastname: Murch
authors.forename: Dan M
authors.initials: DM
authors.lastname: Stamper-Kurn