title: Realization of an excited, strongly correlated quantum gas phase.
abstract: Ultracold atomic physics offers myriad possibilities to study strongly correlated many-body systems in lower dimensions. Typically, only ground-state phases are accessible. Using a tunable quantum gas of bosonic cesium atoms, we realized and controlled in one-dimensional geometry a highly excited quantum phase that is stabilized in the presence of attractive interactions by maintaining and strengthening quantum correlations across a confinement-induced resonance. We diagnosed the crossover from repulsive to attractive interactions in terms of the stiffness and energy of the system. Our results open up the experimental study of metastable, excited, many-body phases with strong correlations and their dynamical properties.
authors.affiliation: Institut für Experimentalphysik und Zentrum für Quantenphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
authors.forename: Elmar
authors.initials: E
authors.lastname: Haller
authors.forename: Mattias
authors.initials: M
authors.lastname: Gustavsson
authors.forename: Manfred J
authors.initials: MJ
authors.lastname: Mark
authors.forename: Johann G
authors.initials: JG
authors.lastname: Danzl
authors.forename: Russell
authors.initials: R
authors.lastname: Hart
authors.forename: Guido
authors.initials: G
authors.lastname: Pupillo
authors.forename: Hanns-Christoph
authors.initials: HC
authors.lastname: Nägerl