Josephson effect in fermionic superfluids across the BEC-BCS crossover

Year: 2015

Authors: Valtolina G., Burchianti A., Amico A., Neri E., Xhani K., Seman J. A., Trombettoni A., Smerzi A., Zaccanti M., Inguscio M., Roati G.

Autors Affiliation: CNR, Ist Nazl Ott, I-50019 Sesto Fiorentino, Italy; European Lab Nonlinear Spect LENS, I-50019 Sesto Fiorentino, Italy; Scuola Normale Super Pisa, Fac Math & Nat Sci, I-56126 Pisa, Italy; Univ Florence, Dept Phys & Astron, I-50019 Sesto Fiorentino, Italy; CNR, Ist Officina Mat, I-34136 Trieste, Italy; Scuola Int Super Studi Avanzati, I-34136 Trieste, Italy; Quantum Sci & Technol Arcetri, I-50125 Florence, Italy; Ist Nazl Ric Metrol, I-10135 Turin, Italy.

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.

Journal/Review: SCIENCE

Volume: 350 (6267)      Pages from: 1505  to: 1508

More Information: We acknowledge inspiring discussions with F. Dalfovo, A. Recati, and W. Zwerger. We thank C. Fort, A. Trenkwalder, A. Morales, and T. Macri for collaboration at the initial stage of this work. We especially acknowledge the LENS Quantum Gases group. This work was supported under European Research Council grant no. 307032 QuFerm2D.
KeyWords: condensate; fluid dynamics; molecular analysis; quantum mechanics; vorticity, Article; conjugate; dynamics; excitation; fermion; liquid; oscillation; priority journal; quantum mechanics; temperature sensitivity; volume; vortex motion
DOI: 10.1126/science.aac9725

Citations: 132
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