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

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 ${\rho }_s$ and the broken-symmetry Cooper pair order parameter ${\Delta }_0$ 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.

Published version

References in corpus (11)

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• The Josephson relation for the superfluid density and the connection to the Goldstone theorem in dilute Bose atomic gasses
• Spin-asymmetric Josephson plasma oscillations
• Leading-Order Auxiliary Field Theory of the Bose-Hubbard Model
• Superfluid density, Josephson relation and pairing fluctuations in a multi-component fermion superfluid