The Layered Fermi Surface State: a new non-equilibrium state of quantum matter

Quantum systems that are periodically driven in time can display striking phenomena with no counterparts in equilibrium. A route to realize non-trivial steady states is to couple these systems to a heat bath to avoid the thermal death towards infinite temperature. We will show that a system of fermions driven by an oscillating electric field and coupled to an ideal thermodynamic heat bath, can realize a new universality class of non-equilibrium states in which the fermi surface is fragmented into several layers and which we call the "Layered Fermi Surface State". We develop a theory of universal measurable quantities of this state, such as its quantum oscillations in magnetic fields, its specific heat, and its lesser Green's function (which can be probed in time resolved ARPES) and discuss its potential realization in materials.