Nonlinear optics and hydrodynamics of graphene
Monday, March 26, 2018 - 2:00pm - 3:00pm
Electrons in pristine solids behave as a hydrodynamic fluid in a certain range of temperatures and frequencies. We show that the response of such a fluid to an electromagnetic field is different from what is predicted by the usual kinetic theory. Certain aspects of this response are universal, for example, a direct relation between the linear and second-order nonlinear optical conductivities. Graphene is a particularly interesting material where this physics can be studied. We show that two types of collective modes should exist therein. Besides the higher-frequency mode, which is the familiar plasmon, graphene should support a lower-frequency mode in the teraherz domain, which is variously referred to as the sound, acoustic plasmon, energy wave, or, as we prefer, the demon. The demon can be studied using the relativistic hydrodynamics approach. We discuss linear and nonlinear phenomena enabled by the demons and how they can be observed in nano-optics experiments.