Strongly Interacting Fermi Gases

Abstract

The experimental realization of stable, ultracold Fermi gases near a Feshbach resonance allows to study gases with attractive interactions of essentially arbitrary strength. They extend the classic paradigm of BCS into a regime which has never been accessible before. We review the theoretical concepts which have been developed in this context, including the Tan relations and the notion of fixed points at zero density, which are at the origin of universality. We discuss in detail the universal thermodynamics of the unitary Fermi gas which allows a fit free comparison between theory and experiment for this strongly interacting system. In addition, we adress the consequences of scale invariance at infinite scattering length and the subtle violation of scale invariance in two dimensions. Finally we discuss the Fermionic excitation spectrum accessible in momentum resolved RF-spectroscopy and the origin of universal lower bounds for the shear viscosity and the spin diffusion constant.

Varenna Lectures, July 2014

Cited by in corpus (13)

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• Stability of interlinked neutron vortex and proton flux tube arrays in a neutron star: equilibrium configurations
• Determination of the density and temperature dependence of the shear viscosity of a unitary Fermi gas based on hydrodynamic flow
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• The contact in the unitary Fermi gas across the superfluid phase transition
• Pairing correlations across the superfluid phase transition in the unitary Fermi gas
• Coherent Oscillations in Small Fermi Polaron Systems
• Quantum critical thermal transport in the unitary Fermi gas
• Universal relations and normal phase of an ultracold Fermi gas with coexisting $s$- and $p$-wave interactions
• Nonrelativistic Conformal Invariance in Mesoscopic Two-Dimensional Fermi Gases
• Mesoscopic pairing without superconductivity
• Collective modes of an imbalanced unitary Fermi gas
• Strong Fulde-Ferrell Larkin-Ovchinnikov pairing fluctuations in polarized Fermi systems