Transport in inhomogeneous quantum critical fluids and in the Dirac fluid in graphene

The possibility of observing a strongly interacting quantum critical fluid of electrons in a metal has intrigued physicists for a long time. The authors combine insight from string theory and condensed matter physics to develop a hydrodynamic theory of the thermal and electrical conductivity of electron fluids. They use this formalism to explain experimental data from a novel state of Dirac electron fluid in clean samples of graphene near the charge neutrality point, and observe substantially improved quantitative agreement over the existing hydrodynamic theories. This study marks the first quantitative connection between these exotic models of transport and experimentally realizable condensed matter systems.