title: Unbounded growth of entanglement in models of many-body localization.
abstract: An important and incompletely answered question is whether a closed quantum system of many interacting particles can be localized by disorder. The time evolution of simple (unentangled) initial states is studied numerically for a system of interacting spinless fermions in one dimension described by the random-field XXZ Hamiltonian. Interactions induce a dramatic change in the propagation of entanglement and a smaller change in the propagation of particles. For even weak interactions, when the system is thought to be in a many-body localized phase, entanglement shows neither localized nor diffusive behavior but grows without limit in an infinite system: interactions act as a singular perturbation on the localized state with no interactions. The significance for proposed atomic experiments is that local measurements will show a large but nonthermal entropy in the many-body localized state. This entropy develops slowly (approximately logarithmically) over a diverging time scale as in glassy systems.
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720, USA.
authors.forename: Jens H
authors.initials: JH
authors.lastname: Bardarson
authors.forename: Frank
authors.initials: F
authors.lastname: Pollmann
authors.forename: Joel E
authors.initials: JE
authors.lastname: Moore