## Long-lived interacting phases of matter protected by multiple time-translation symmetries in quasiperiodically driven systems

**Speaker:**Dominic Else, Massachusetts Institute of Technology

**When:**November 1, 2019 (Fri), 12:00PM to 01:30PM (add to my calendar)

**Location:**SCI 352

**Hosted by:**Philip Crowley

*This event is part of the Biophysics/Condensed Matter Seminar Series. *

The discrete time-translation symmetry of a periodically-driven (Floquet) system allows for the existence of novel, nonequilibrium interacting phases of matter. A well-known example is the discrete time crystal, a phase characterized by the spontaneous breaking of this time-translation symmetry. In this talk, I will show that the presence of *multiple* time-translational symmetries, realized by quasiperiodically driving a system with two or more incommensurate frequencies, leads to a panoply of novel non-equilibrium phases of matter, both spontaneous symmetry breaking ("discrete time quasi-crystals") and topological.
In order to stabilize such phases, I will outline rigorous mathematical results establishing slow heating of systems driven quasiperiodically at high frequencies. As a byproduct, I will introduce the notion of many-body localization (MBL) in quasiperiodically driven systems.