title: Momentum-Resolved Observation of Thermal and Quantum Depletion in a Bose Gas.
abstract: We report on the single-atom-resolved measurement of the distribution of momenta ℏk in a weakly interacting Bose gas after a 330 ms time of flight. We investigate it for various temperatures and clearly separate two contributions to the depletion of the condensate by their k dependence. The first one is the thermal depletion. The second contribution falls off as k^{-4}, and its magnitude increases with the in-trap condensate density as predicted by the Bogoliubov theory at zero temperature. These observations suggest associating it with the quantum depletion. How this contribution can survive the expansion of the released interacting condensate is an intriguing open question.
authors.affiliation: Laboratoire Charles Fabry, Institut d'Optique, CNRS, Univ. Paris Sud, 2 Avenue Augustin Fresnel 91127 PALAISEAU cedex, France.
authors.forename: R
authors.initials: R
authors.lastname: Chang
authors.affiliation: Laboratoire Charles Fabry, Institut d'Optique, CNRS, Univ. Paris Sud, 2 Avenue Augustin Fresnel 91127 PALAISEAU cedex, France.
authors.forename: Q
authors.initials: Q
authors.lastname: Bouton
authors.affiliation: Laboratoire Charles Fabry, Institut d'Optique, CNRS, Univ. Paris Sud, 2 Avenue Augustin Fresnel 91127 PALAISEAU cedex, France.
authors.forename: H
authors.initials: H
authors.lastname: Cayla
authors.affiliation: INO-CNR BEC Center and Dipartimento di Fisica, Universita di Trento, 38123 Povo, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Qu
authors.affiliation: Laboratoire Charles Fabry, Institut d'Optique, CNRS, Univ. Paris Sud, 2 Avenue Augustin Fresnel 91127 PALAISEAU cedex, France.
authors.forename: A
authors.initials: A
authors.lastname: Aspect
authors.affiliation: Laboratoire Charles Fabry, Institut d'Optique, CNRS, Univ. Paris Sud, 2 Avenue Augustin Fresnel 91127 PALAISEAU cedex, France.
authors.forename: C I
authors.initials: CI
authors.lastname: Westbrook
authors.affiliation: Laboratoire Charles Fabry, Institut d'Optique, CNRS, Univ. Paris Sud, 2 Avenue Augustin Fresnel 91127 PALAISEAU cedex, France.
authors.forename: D
authors.initials: D
authors.lastname: Clément