Critical Josephson current in BCS-BEC-crossover superfluids

Year: 2019

Authors: Zaccanti M., Zwerger W.

Autors Affiliation: CNR, INO, I-50019 Sesto Fiorentino, Italy; Univ Firenze, LENS, I-50019 Sesto Fiorentino, Italy; Univ Firenze, Dipartimento Fis & Astron, I-50019 Sesto Fiorentino, Italy; Tech Univ Munich, Phys Dept, D-85748 Garching, Germany

Abstract: We develop a microscopic model to describe the Josephson tunneling between two superfluid reservoirs of ultracold fermionic atoms which accounts for the dependence of the critical current on both the barrier height and the interaction strength along the crossover from the BCS to the BEC regime. Building on a previous study [F. Meier and W. Zwerger, Phys. Rev. A 64, 033610 (2001)] of weakly interacting bosons, we derive analytic results for the Josephson critical current at zero temperature for homogeneous and trapped systems at arbitrary coupling. The critical current exhibits a maximum near the unitarity limit which arises from the competition between the increasing condensate fraction and a decrease in the chemical potential along the evolution from the BCS to the BEC limit. Our results agree quantitatively with numerical simulations and recent experimental data


Volume: 100 (6)      Pages from: 063601-1  to: 063601-8

More Information: We thank F. Dalfovo and P. Zou for providing the chemical potential values relevant to analysis of the data in Ref. [27], K. Xhani for sharing the ETFM results reported in Ref. [47] for trapped BECs, and B. Frank for the nonperturbative results shown in Fig. 2 and employed to analyze the experimental data in Fig. 4. We acknowledge fruitful discussions with F. Dalfovo, E. Neri, A. Recati, G. Roati, F. Scazza, and K. Xhani. This work was supported by the ERC through Grant No. 637738 PoLiChroM and in part also by the Nano-Initiative Munich (NIM).
DOI: 10.1103/PhysRevA.100.063601

Citations: 26
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