title: Collective modes in a unitary Fermi gas across the superfluid phase transition.
abstract: We provide a joint theoretical and experimental investigation of the temperature dependence of the collective oscillations of first sound nature exhibited by a highly elongated harmonically trapped Fermi gas at unitarity, including the region below the critical temperature for superfluidity. Differently from the lowest axial breathing mode, the hydrodynamic frequencies of the higher-nodal excitations show a temperature dependence, which is calculated starting from Landau two-fluid theory and using the available experimental knowledge of the equation of state. The experimental results agree with high accuracy with the predictions of theory and provide the first evidence for the temperature dependence of the collective frequencies near the superfluid phase transition.
authors: Institut für Quantenoptik und Quanteninformation (IQOQI), Österreichische Akademie der Wissenschaften and Institut für Experimentalphysik, Universität Innsbruck, 6020 Innsbruck, Austria.
authors: Meng Khoon
authors: MK
authors: Tey
authors: Leonid A
authors: LA
authors: Sidorenkov
authors: Edmundo R Sánchez
authors: ER
authors: Guajardo
authors: Rudolf
authors: R
authors: Grimm
authors: Mark J H
authors: MJ
authors: Ku
authors: Martin W
authors: MW
authors: Zwierlein
authors: Yan-Hua
authors: YH
authors: Hou
authors: Lev
authors: L
authors: Pitaevskii
authors: Sandro
authors: S
authors: Stringari