Quasiparticle excitations and dynamic susceptibilities in the BCS-BEC crossover

Abstract

We study dynamic ground state properties in the crossover from weak (BCS) to strong coupling (BEC) superfluidity. Our approach is based on the attractive Hubbard model which is analyzed by the dynamical mean field theory (DMFT) combined with the numerical renormalization group (NRG). We present an extension of the NRG method for effective impurity models to selfconsistent calculations with superconducting symmetry breaking. In the one particle spectra we show quantitatively how the Bogoliubov quasiparticles at weak coupling become suppressed at intermediate coupling. We also present results for the spin and charge gap. The extension of the NRG method to selfconsistent superconducting solutions opens the possibility to study a range of other important applications.

6 pages, 5 figures (minor amendments and additional reference)

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• Quantitative reliability of Migdal-Eliashberg theory for strong electron-phonon coupling
• When Superconductivity Crosses Over: From BCS to BEC
• Dynamical mean-field theory and numerical renormalization group study of superconductivity in the attractive Hubbard model
• Low temperature properties of the infinite-dimensional attractive Hubbard model
• Local origin of the pseudogap in the attractive Hubbard model
• LDA+DMFT approach to ordering phenomena and the structural stability of correlated materials
• Low temperature properties of the fermionic mixtures with mass imbalance in optical lattice
• Spontaneously symmetry breaking states in the attractive SU$(N)$ Hubbard model
• Hidden fermionic excitation in the superconductivity of the strongly attractive Hubbard model
• A real space auxiliary field approach to the BCS-BEC crossover
• Stability of the Superfluid State in Three-Component Fermionic Optical Lattice Systems
• Polarized superfluid state in a three-dimensional fermionic optical lattice
• Embedding Dynamical Mean-Field Theory for Superconductivity in Layered Materials and Heterostructures
• Superfluid gap formation in a fermionic optical lattice with spin imbalanced populations