We are a Theoretical Physics group at UC Berkeley specializing in the study of Condensed Matter Physics. We seek to understand properties of matter such as superconductivity and magnetism starting from fundamental physical laws like quantum mechanics. Historically, this has led to a deeper understanding of interacting quantum systems of very many particles as well as applications like the transistor, magnetic memories and magnetic resonance imaging .
This wordle gives you a picture of our current interests which includes topological phases with strong interactions, unconventional quantum critical points and and three dimensional zero-gap semiconductors (i.e. Weyl and Dirac semimetals). We explore both the fundamental theory of such states, as well as their experimental signatures.
We use a variety of theoretical tools, e.g. quantum field theory, but our research is primarily guided by interesting physical problems and ideas rather than techniques. We are happy to pick up new tools if they suite the problem at hand - for example we recently exploited concepts from quantum information theory to sharpen our understanding of topological phases. We also work closely with experimental groups that study interesting states of matter in solids and ultracold atomic systems.
(i) Particle-vortex duality of 2d Dirac fermion from electric-magnetic duality of 3d topological insulators (with Max Metlitski)
The physics of a single Dirac cone, the surface of a Topological Insulator (TI), is proposed to be described by a dual theory, QED3 of a gauge field coupled to a Dirac fermion which is the surface of a topological superconductor. The dual theory provides an explicit derivation of the T-Pfaffian state, a proposed surface topological order of the TI, which is the pair-condensed state of the dual fermions.