Density and spin response function of a normal Fermi gas at unitarity

Abstract

Using Landau theory of Fermi liquids we calculate the dynamic response of both a polarized and unpolarized normal Fermi gas at zero temperature in the strongly interacting regime of large scattering length. We show that at small excitation energies the {\it in phase} (density) response is enhanced with respect to the ideal gas prediction due to the increased compressibility. Viceversa, the {\it out of phase} (spin) response is quenched as a consequence of the tendency of the system to pair opposite spins. The long wavelength behavior of the static structure factor is explicitly calculated. The results are compared with the predictions in the collisional and superfluid regimes. The emergence of a spin zero sound solution in the unpolarized normal phase is explicitly discussed.

4 pages, 2 figures

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• Thermal instability, evaporation and thermodynamics of one-dimensional liquids in weakly-interacting Bose-Bose mixtures
• Magnetic phase transition in a mixture of two interacting Bose gases at finite temperature
• Establishing the Presence of Coherence in Atomic Fermi Superfluids: Spin-Flip and Spin-Preserving Bragg Scattering at Finite Temperatures
• Quantitative comparison between theoretical predictions and experimental results for Bragg spectroscopy of a strongly interacting Fermi superfluid
• Low-momentum dynamic structure factor of a strongly interacting Fermi gas at finite temperature: The Goldstone phonon and its Landau damping
• Induced P-wave superfluidity within full energy-momentum dependent Eliashberg approximation in asymmetric dilute Fermi gases
• BCS-BEC crossover in a trapped Fermi super-fluid using a density-functional equation
• Fermi liquid theory of ultra-cold trapped Fermi gases: Implications for Pseudogap Physics and Other Strongly Correlated Phases
• Dynamical spin-flip susceptibility for a strongly interacting ultracold Fermi gas
• Dynamic structure factor of a strongly correlated Fermi superfluid within a density functional theory approach
• Dynamic Structure Factor of Normal Fermi Gas from Collisionless to Hydrodynamic Regime
• Density and spin modes in imbalanced normal Fermi gases from collisionless to hydrodynamic regime
• Many-body theories of density response for a strongly correlated Fermi gas
• Response function of strongly interacting Fermi gas in a virial expansion
• Emergence of Sound in a Tunable Fermi Fluid
• Tunable zero and first sounds in ultracold Fermi gases with Rabi coupling
• Counterflow in a doubly superfluid mixture of Bosons and Fermions