title: Josephson effect in fermionic superfluids across the BEC-BCS crossover.
abstract: The Josephson effect is a macroscopic quantum phenomenon that reveals the broken symmetry associated with any superfluid state. Here we report on the observation of the Josephson effect between two fermionic superfluids coupled through a thin tunneling barrier. We show that the relative population and phase are canonically conjugate dynamical variables throughout the crossover from the molecular Bose-Einstein condensate (BEC) to the Bardeen-Cooper-Schrieffer (BCS) superfluid regime. For larger initial excitations from equilibrium, the dynamics of the superfluids become dissipative, which we ascribe to the propagation of vortices through the superfluid bulk. Our results highlight the robust nature of resonant superfluids.
authors.affiliation: Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR), 50019 Sesto Fiorentino, Italy. European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy. Faculty of Mathematic and Natural Sciences, Scuola Normale Superiore, 56126 Pisa, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Valtolina
authors.affiliation: Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR), 50019 Sesto Fiorentino, Italy. European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Burchianti
authors.affiliation: Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR), 50019 Sesto Fiorentino, Italy. European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy. Department of Physics and Astronomy, University of Florence, 50019 Sesto Fiorentino, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Amico
authors.affiliation: Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR), 50019 Sesto Fiorentino, Italy. European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy. Department of Physics and Astronomy, University of Florence, 50019 Sesto Fiorentino, Italy.
authors.forename: Elettra
authors.initials: E
authors.lastname: Neri
authors.affiliation: Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR), 50019 Sesto Fiorentino, Italy. European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy.
authors.forename: Klejdja
authors.initials: K
authors.lastname: Xhani
authors.affiliation: Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR), 50019 Sesto Fiorentino, Italy.
authors.forename: Jorge Amin
authors.initials: JA
authors.lastname: Seman
authors.affiliation: Istituto Officina dei Materiali del CNR and Scuola Internazionale Superiore di Studi Avanzati, I-34136 Trieste, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Trombettoni
authors.affiliation: Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR), 50019 Sesto Fiorentino, Italy. European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy. Quantum Science and Technology in Arcetri, I-50125 Firenze, Italy.
authors.forename: Augusto
authors.initials: A
authors.lastname: Smerzi
authors.affiliation: Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR), 50019 Sesto Fiorentino, Italy. European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Zaccanti
authors.affiliation: European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy. Department of Physics and Astronomy, University of Florence, 50019 Sesto Fiorentino, Italy. Istituto Nazionale di Ricerca Metrologica, 10135 Torino, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Inguscio
authors.affiliation: Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR), 50019 Sesto Fiorentino, Italy. European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy. giacomo.roati@ino.it.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Roati