Strange Metals, Black Holes, and Graphene

Sachdev 2016 10 17

Subir Sachdev
Harvard University
October 17, 2016

States of quantum matter without quasiparticles can be more precisely characterized by their rapid approach to local thermal equilibrium: this is argued to happen in a shortest possible time of order (Planck’s constant)/((Boltmann’s constant)x(absolute temperature)). Black holes are physical systems which also equilibrate in this time, with the absolute temperature identified as the Hawking temperature. And this similarity is not a co-incidence: the Sachdev-Ye-Kitaev model of a “strange metal” without quasiparticle excitations, also turns out to be a theory of a black hole in 1+1 dimensional anti-de Sitter space. I will discuss a general formulation of a transport theory of states of matter without quasiparticle excitations, which was inspired by these black hole analogies. This formulation leads to experimental predictions, including some that  agree well with recent observations on graphene.