Popov approximation for composite bosons in the BCS-BEC crossover

Abstract

Theoretical treatments of the BCS-BEC crossover need to provide as accurate as possible descriptions of the two regimes where the diluteness condition applies, either in terms of the constituent fermions (BCS limit) or of the composite bosons which form as bound-fermion pairs (BEC limit). This has to occur via a single fermionic theory that bridges across these two limiting representations. In this paper, we set up successive improvements of the fermionic theory, that result into composite bosons described at the level of either the Bogoliubov or the Popov approximations for point-like bosons. This work bears on the recent experimental advances on the BCS-BEC crossover with trapped Fermi atoms, which show the need for accurate theoretical descriptions of BEC side of the crossover.

13 pages, 4 figures

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Cited by in corpus (23)

• The BCS-BEC crossover: From ultra-cold Fermi gases to nuclear systems
• Trapped Fermions across a Feshbach resonance with population imbalance
• Superfluid density and condensate fraction in the BCS-BEC crossover regime at finite temperatures
• Imbalanced Fermi Gases at Unitarity
• Intermediate temperature superfluidity in an atomic Fermi gas with population imbalance
• Temperature and coupling dependence of the universal contact intensity for an ultracold Fermi gas
• When Superconductivity Crosses Over: From BCS to BEC
• Density and spin response of a strongly-interacting Fermi gas in the attractive and quasi-repulsive regime
• Comparative Study of BCS-BEC Crossover Theories above $T_c$: the Nature of the Pseudogap in Ultra-Cold Atomic Fermi Gases
• Thermodynamics and superfluid density in BCS-BEC crossover with and without population imbalance
• Comparison of Different Pairing Fluctuation Approaches to BCS-BEC Crossover
• Entanglement between pairing and screening in the Gorkov-Melik-Barkhudarov correction to the critical temperature throughout the BCS-BEC crossover
• Gap equation with pairing correlations beyond mean field and its equivalence to a Hugenholtz-Pines condition for fermion pairs
• Theory of Superfluids with Population Imbalance: Finite Temperature and BCS-BEC Crossover Effects
• Dynamical instability of a driven-dissipative electron-hole condensate in the BCS-BEC-crossover region
• Critical Behaviour in Trapped Strongly Interacting Fermi Gases
• Fermions with attractive interactions on optical lattices and implications for correlated systems
• Local Photoemission Spectra and Effects of Spatial Inhomogeneity in the BCS-BEC Crossover Regime of a Trapped Ultracold Fermi Gas
• Interacting Preformed Cooper Pairs in Resonant Fermi Gases
• The Josephson relation for the superfluid density in the BCS-BEC crossover
• Correcting inconsistencies in the conventional superfluid path integral scheme
• Dressed-molecules in resonantly-interacting ultracold atomic Fermi gases
• Comment on "Density and Spin response of a strongly-interacting Fermi gas in the attractive and quasi-repulsive regime"