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arXiv · 0801.4579

The Josephson relation for the superfluid density in the BCS-BEC crossover

Edward Taylor
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Abstract

The Josephson relation for the superfluid density is derived for a Fermi superfluid in the BCS-BEC crossover. This identity extends the original Josephson relation for Bose superfluids. It gives a simple exact relation between the superfluid density $ρ_s$ and the broken-symmetry Cooper pair order parameter $Δ_0$ in terms of the infrared limit of the pair fluctuation propagator. The same expression holds through the entire BCS-BEC crossover, describing the superfluid density of a weak-coupling BCS superfluid as well as the superfluid density of a Bose condensate of dimer molecules.

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Edward Taylor. 2008-04-23. The Josephson relation for the superfluid density in the BCS-BEC crossover. https://doi.org/10.1103/physrevb.77.144521

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