This program will focus on the manifestations of quantum mechanics in highly excited many-body systems. The common assumption that interacting systems equilibrate under their own dynamics has been challenged by recent studies.  Several concrete examples, united under the moniker of “many-body localization”, demonstrate that interacting systems can instead exist in localized states, which retain quantum coherence.  In contrast to equilibrated systems, localized systems may exhibit quantum order even at high temperature and thus act as interacting quantum memories for extended periods.  Alternatively, many-body systems may exhibit very slow dynamics and long pre-thermal behavior as a consequence of emergent constants of motion. 

The implications of many-body localization are far-reaching:  quenching of transport, slow growth of entanglement, the existence of novel non-equilibrium phases and phase transitions forbidden by statistical mechanics, and self-localizing systems, such as the “ideal” glass.  The primary goals of the program are to generalize notions of equilibrium statistical mechanics such as universality and order to many-body localization, systemize model paradigms, and establish firm connections between models and experiments.