Density functional theory for atomic Fermi gases

The interplay between interaction and inhomogeneity for electrons in solids generates many interesting phenomena, including insulating and metallic behaviour, magnetism, superconductivity, quantum criticality and more exotic phases 1 . Many of the same phenomena appear in ultracold fermionic atoms in optical lattices 2 , which provide clean, controlled and tunable 'quantum simulators' to explore the intriguing physics of fermionic systems. Although density functional theory 3-5 (DFT) is widely used to calculate material properties 6 , it has not yet been applied to cold atomic gases in optical lattices. Here we present a new density functional for short-range interactions (as opposed to Coulomb interactions of electrons), which renders DFT suitable for atomic Fermi gases. This grants us access to an extensive toolset, previously developed for materials simulations, to calculate the static and dynamic properties of atomic Fermi gases in optical lattices and external potentials. Ultracold atom quantum simulators can in turn be used to explore limitations of DFT functionals, and to further improve hybrid functionals, thus forming a bridge between materials simulations and atomic physics. © 2012 Macmillan Publishers Limited. All rights reserved.