title: A mixture of Bose and Fermi superfluids.
abstract: Superconductivity and superfluidity of fermionic and bosonic systems are remarkable many-body quantum phenomena. In liquid helium and dilute gases, Bose and Fermi superfluidity has been observed separately, but producing a mixture in which both the fermionic and the bosonic components are superfluid is challenging. Here we report on the observation of such a mixture with dilute gases of two lithium isotopes, lithium-6 and lithium-7. We probe the collective dynamics of this system by exciting center-of-mass oscillations that exhibit extremely low damping below a certain critical velocity. Using high-precision spectroscopy of these modes, we observe coherent energy exchange and measure the coupling between the two superfluids. Our observations can be captured theoretically using a sum-rule approach that we interpret in terms of two coupled oscillators.
authors.affiliation: Laboratoire Kastler-Brossel, École Normale Supérieure, Collège de France, CNRS and UPMC, 24 rue Lhomond, 75005 Paris, France. iferrier@lkb.ens.fr.
authors.forename: I
authors.initials: I
authors.lastname: Ferrier-Barbut
authors.affiliation: Laboratoire Kastler-Brossel, École Normale Supérieure, Collège de France, CNRS and UPMC, 24 rue Lhomond, 75005 Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Delehaye
authors.affiliation: Laboratoire Kastler-Brossel, École Normale Supérieure, Collège de France, CNRS and UPMC, 24 rue Lhomond, 75005 Paris, France.
authors.forename: S
authors.initials: S
authors.lastname: Laurent
authors.affiliation: Laboratoire Kastler-Brossel, École Normale Supérieure, Collège de France, CNRS and UPMC, 24 rue Lhomond, 75005 Paris, France.
authors.forename: A T
authors.initials: AT
authors.lastname: Grier
authors.affiliation: Laboratoire Kastler-Brossel, École Normale Supérieure, Collège de France, CNRS and UPMC, 24 rue Lhomond, 75005 Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Pierce
authors.affiliation: Laboratoire Kastler-Brossel, École Normale Supérieure, Collège de France, CNRS and UPMC, 24 rue Lhomond, 75005 Paris, France.
authors.forename: B S
authors.initials: BS
authors.lastname: Rem
authors.affiliation: Laboratoire Kastler-Brossel, École Normale Supérieure, Collège de France, CNRS and UPMC, 24 rue Lhomond, 75005 Paris, France.
authors.forename: F
authors.initials: F
authors.lastname: Chevy
authors.affiliation: Laboratoire Kastler-Brossel, École Normale Supérieure, Collège de France, CNRS and UPMC, 24 rue Lhomond, 75005 Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Salomon