title: Critical behavior of a trapped interacting Bose gas.
abstract: The phase transition of Bose-Einstein condensation was studied in the critical regime, where fluctuations extend far beyond the length scale of thermal de Broglie waves. We used matter-wave interference to measure the correlation length of these critical fluctuations as a function of temperature. Observations of the diverging behavior of the correlation length above the critical temperature enabled us to determine the critical exponent of the correlation length for a trapped, weakly interacting Bose gas to be nu = 0.67 +/- 0.13. This measurement has direct implications for the understanding of second-order phase transitions.
authors.affiliation: Institute of Quantum Electronics, Eidgenössische Technische Hochschule (ETH) Zürich, CH-8093 Zürich, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Donner
authors.forename: S
authors.initials: S
authors.lastname: Ritter
authors.forename: T
authors.initials: T
authors.lastname: Bourdel
authors.forename: A
authors.initials: A
authors.lastname: Ottl
authors.forename: M
authors.initials: M
authors.lastname: Köhl
authors.forename: T
authors.initials: T
authors.lastname: Esslinger