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In recent years, many-body localization and the prediction of a metal-insulator transition at finite temperature has attracted a lot of attention as a way to maintain permanent off-equilibrium conditions in a thermodynamic, but closed quantum many-body system. Such transitions, driven by energy density (or ”temperature”), require the presence of a many-body mobility edge in energy, that separates localized from ergodic states. I argue that for short range interactions this scenario is beyond the control of perturbation theory and seems inconsistent due to inclusions of the ergodic phase in the supposedly localized phase. Those inclusions are mobile and induce global delocalization. These considerations modify the phase diagrams for interacting systems both with and without quenched disorder.

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Markus Mueller, Paul-Scherrer Institut
Seminar room 0.03, ETP
Contact: Philipp Strack