title: Many-body treatment of the collisional frequency shift in fermionic atoms.
abstract: Recent experiments have measured collisional frequency shifts in polarized fermionic alkaline-earth atoms using 1S0-3P0 Rabi spectroscopy. Here, we provide a first-principles nonequilibrium theoretical description of the interaction frequency shifts starting from the microscopic many-body Hamiltonian. Our formalism describes the dependence of the frequency shift on excitation inhomogeneity, interactions, temperature, and many-body dynamics, provides a fundamental understanding of the effects of the measurement process, and explains the observed density shift data.
authors.affiliation: JILA, NIST, and Department of Physics, University of Colorado Boulder, Colorado 80309, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Rey
authors.forename: A V
authors.initials: AV
authors.lastname: Gorshkov
authors.forename: C
authors.initials: C
authors.lastname: Rubbo