Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 29: Focus Session: Dynamics in Many-Body Systems: Equilibration and Localization (joint session TT/DY)

TT 29.2: Hauptvortrag

Dienstag, 17. März 2015, 10:00–10:30, H 0104

Many-Body Localization — •Dmitry Abanin — University of Geneva, Switzerland — Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada

We are used to describing systems of many particles by statistical mechanics. However, the basic postulate of statistical mechanics – ergodicity – breaks down in so-called many-body localized systems, where disorder prevents particle transport and thermalization. In this talk, I will give an overview of recent developments in many-body localization. I will describe a phenomenological theory of the many-body localized (MBL) phase, based on new insights from quantum entanglement. I will argue that, in contrast to ergodic systems, MBL eigenstates are not highly entangled, but rather obey so-called area law, typical of ground states in gapped systems. I will use this fact to show that MBL phase is characterized by an infinite number of emergent local conservation laws, in terms of which the Hamiltonian acquires a universal form. Turning to the experimental implications, I will describe the response of an MBL systems to quenches: surprisingly, entanglement shows logarithmic in time growth, reminiscent of glasses, while local observables exhibit power-law approach to “equilibrium” values. I will support the presented theory with the results of numerical experiments, and close by discussing experimental implications and other directions in exploring ergodicity and its breaking in quantum many-body systems.