title: Rigorous Bound on Energy Absorption and Generic Relaxation in Periodically Driven Quantum Systems.
abstract: We discuss the universal nature of relaxation in isolated many-body quantum systems subjected to global and strong periodic driving. Our rigorous Floquet analysis shows that the energy of the system remains almost constant up to an exponentially long time in frequency for arbitrary initial states and that an effective Hamiltonian obtained by a truncation of the Floquet-Magnus expansion is a quasiconserved quantity in a long time scale. These two general properties lead to an intriguing classification on the initial stage of relaxation, one of which is similar to the prethermalization phenomenon in nearly integrable systems.
authors.affiliation: Department of Physics, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Mori
authors.affiliation: WPI, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Tomotaka
authors.initials: T
authors.lastname: Kuwahara
authors.affiliation: Department of Physics, Keio University, Yokohama 223-8522, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Saito