The Compressibility in Strongly Correlated Superconductors and Superfluids: From BCS to BEC

Abstract

We present a theoretical study of the compressibility, $\kappa$, in a Fermi gas with attractive contact interactions, providing predictions for the strongly-attractive regime and the superfluid phase. Our work emphasizes the compressibility sum rule and gauge invariance as constraints on $\kappa$ and we show how within a particular $t$-matrix approach, these can be satisfied in the normal phase when no approximations are made. For tractability, approximations must be introduced, and it is believed that thermodynamical approaches to $\kappa$ are more reliable, than correlation function based schemes. Contrasting with other studies in the literature, we present thermodynamic calculations of $\kappa$; these yield semi-quantitative agreement with experiment and provide physical insight into similar results obtained via quantum Monte Carlo simulations.

5 pages, 1 figure

References in corpus (6)

• Using photoemission spectroscopy to probe a strongly interacting Fermi gas
• Thermodynamics of the BCS-BEC crossover
• BCS-BEC crossover at finite temperature in the broken-symmetry phase
• Speckle Imaging of Spin Fluctuations in a Strongly Interacting Fermi Gas
• Quantum mechanical limitations to spin diffusion in the unitary Fermi gas
• Theories of Linear Response in BCS Superfluids and How They Meet Fundamental Constraints

Cited by in corpus (8)

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• Thermodynamic Properties of Rashba Spin-Orbit-Coupled Fermi Gas
• Mobile impurity probing a two-dimensional superfluid phase transition
• Density and Spin Linear Response of Atomic Fermi Superfluids with Population Imbalance in BCS-BEC Crossover
• Phonon renormalization and Pomeranchuk instability in the Holstein model
• Response functions of hot and dense matter in the Nambu-Jona-Lasino model
• Anomalous isothermal compressibility in spin-orbit coupled degenerate Fermi gases
• Two-component atomic Fermi superfluid with spin-orbital coupling in thin spherical-shell geometry