title: Entanglement prethermalization in an interaction quench between two harmonic oscillators.
abstract: Entanglement prethermalization (EP) refers to a quasi-stationary nonequilibrium state of a composite system in which each individual subsystem looks thermal but the entire system remains nonthermal due to quantum entanglement between subsystems. We theoretically study the dynamics of EP following a coherent split of a one-dimensional harmonic potential in which two interacting bosons are confined. This problem is equivalent to that of an interaction quench between two harmonic oscillators. We show that this simple model captures the bare essentials of EP; that is, each subsystem relaxes to an approximate thermal equilibrium, whereas the total system remains entangled. We find that a generalized Gibbs ensemble exactly describes the total system if we take into account nonlocal conserved quantities that act nontrivially on both subsystems. In the presence of a symmetry-breaking perturbation, the relaxation dynamics of the system exhibits a quasi-stationary EP plateau and eventually reaches thermal equilibrium. We analytically show that the lifetime of EP is inversely proportional to the magnitude of the perturbation.
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.|Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.|Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Tatsuhiko N
authors.initials: TN
authors.lastname: Ikeda
authors.affiliation: Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Mori
authors.affiliation: Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Kaminishi
authors.affiliation: Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.|RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Ueda