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Mean-field vs. Monte Carlo equation of state for the expansion of a Fermi superfluid in the BCS-BEC crossover

2006/09/04 by Luca Salasnich, Nicola Manini · 2 citations
Physics and Astronomy · #Atomic and Subatomic Physics Research #Cold Atom Physics and Bose-Einstein Condensates #Quantum, superfluid, helium dynamics #cond-mat.other

paper · pdf · doi:10.1134/s1054660x07020211

published as Laser Physics, vol. 17, 169-173 (2007) · 13 pages, 3 figures, presented to the 15th International Laser Physics Workshop (Lausanne, July 24-28, 2006); to be published in Laser Physics

arxiv created 2006/09/04 · openalex publication_date 2007/02/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

The equation of state (EOS) of a Fermi superfluid is investigated in the BCS-BEC crossover at zero temperature. We discuss the EOS based on Monte Carlo (MC) data and asymptotic expansions and the EOS derived from the extended BCS (EBCS) mean-field theory. Then we introduce a time-dependent density functional, based on the bulk EOS and Landau’s superfluid hydrodynamics with a von Weizsäcker-type correction, to study the free expansion of the Fermi superfluid. We calculate the aspect ratio and the released energy of the expanding Fermi cloud showing that MC EOS and EBCS EOS are both compatible with the available experimental data of 6 Li atoms. We find that the released energy satisfies and approximate analytical formula that is quite accurate in the BEC regime. For an anisotropic droplet, our numerical simulations show an initially faster reversal of anisotropy in the BCS regime, later suppressed by the BEC fluid.

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