title: Observation of phase fluctuations in elongated Bose-Einstein condensates.
abstract: The occurrence of phase fluctuations due to thermal excitations in Bose-Einstein condensates (BECs) is studied for a variety of temperatures and trap geometries. We observe the statistical nature of the appearance of phase fluctuations and characterize the dependence of their average value on temperature, number of particles, and the trapping potential. We find pronounced phase fluctuations for condensates in very elongated traps in a broad temperature range. The results are of great importance for the realization of BEC in quasi-1D geometries, for matter wave interferometry with BECs, as well as for coherence properties of guided atom laser beams.
authors.affiliation: Institut für Quantenoptik, Universität Hannover, Welfengarten 1, 30167 Hannover, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Dettmer
authors.forename: D
authors.initials: D
authors.lastname: Hellweg
authors.forename: P
authors.initials: P
authors.lastname: Ryytty
authors.forename: J J
authors.initials: JJ
authors.lastname: Arlt
authors.forename: W
authors.initials: W
authors.lastname: Ertmer
authors.forename: K
authors.initials: K
authors.lastname: Sengstock
authors.forename: D S
authors.initials: DS
authors.lastname: Petrov
authors.forename: G V
authors.initials: GV
authors.lastname: Shlyapnikov
authors.forename: H
authors.initials: H
authors.lastname: Kreutzmann
authors.forename: L
authors.initials: L
authors.lastname: Santos
authors.forename: M
authors.initials: M
authors.lastname: Lewenstein