title: Probing three-body correlations in a quantum gas using the measurement of the third moment of density fluctuations.
abstract: We perform measurements of the third moment of atom number fluctuations in small slices of a very elongated weakly interacting degenerate Bose gas. We find a positive skewness of the atom number distribution in the ideal gas regime and a reduced skewness compatible with zero in the quasicondensate regime. For our parameters, the third moment is a thermodynamic quantity whose measurement constitutes a sensitive test of the equation of state, and our results are in agreement with a modified Yang-Yang thermodynamic prediction. Moreover, we show that the measured skewness reveals the presence of true three-body correlations in the system.
authors.affiliation: Laboratoire Charles Fabry, UMR 8501 du CNRS, Institut d'Optique, 91 127 Palaiseau Cedex, France.
authors.forename: J
authors.initials: J
authors.lastname: Armijo
authors.forename: T
authors.initials: T
authors.lastname: Jacqmin
authors.forename: K V
authors.initials: KV
authors.lastname: Kheruntsyan
authors.forename: I
authors.initials: I
authors.lastname: Bouchoule