Condensed Matter Seminars

A recurring theme in classical and quantum dynamics is finding examples of systems which fail to thermalize.  We introduce a class of 1D translationally invariant classical and quantum dynamics that have an unusual approach to equilibrium.  For certain examples, expectation values of local operators relax in a time which is exponentially large in system size, implying an unusual kind of hydrodynamics.  In other examples, thermalization only occurs when the system is connected to a bath which is at least exponentially large in system size, a phenomenon that we call fragile fragmentation.  A field of mathematics called geometric group theory plays an important role in constructing these examples, and we discuss extensions of these results to 2D.