title: Quantum dynamics of the Hubbard-Holstein model in equilibrium and nonequilibrium: application to pump-probe phenomena.
abstract: The spectral response and physical features of the 2D Hubbard-Holstein model are calculated both in equilibrium at zero and low chemical dopings, and after an ultrashort powerful light pulse, in undoped systems. At equilibrium and at strong charge-lattice couplings, the optical conductivity reveals a three-peak structure in agreement with experimental observations. After an ultrashort pulse and at nonzero electron-phonon interaction, phonon and spin subsystems oscillate with the phonon period T(ph)≈80 fs. The decay time of the phonon oscillations is about 150-200 fs, similar to the relaxation time of the charge system. We propose a criterion for observing these oscillations in high T(c) compounds: the time span of the pump light pulse τ(pump) has to be shorter than the phonon oscillation period T(ph).
authors.affiliation: SPIN-CNR and Dipartimento di Scienze Fisiche-Università di Napoli Federico II-I-80126 Napoli, Italy.
authors.forename: G
authors.initials: G
authors.lastname: De Filippis
authors.forename: V
authors.initials: V
authors.lastname: Cataudella
authors.forename: E A
authors.initials: EA
authors.lastname: Nowadnick
authors.forename: T P
authors.initials: TP
authors.lastname: Devereaux
authors.forename: A S
authors.initials: AS
authors.lastname: Mishchenko
authors.forename: N
authors.initials: N
authors.lastname: Nagaosa