Seminar By Joseph Maciejko,University of Alberta
Title: Superconducting Dirac fermions and mirror symmetry
Abstract: In the presence of strong interactions, the gapless boundary modes of topological insulators/superconductors are potential platforms for observing exotic types of quantum criticality. It was recently shown that the semimetal-superconductor quantum phase transition for a single 2D Dirac fermion, such as found on the surface of a 3D topological insulator, exhibits an emergent supersymmetry with the Dirac fermions and Cooper pairs behaving as superpartners. In this talk I will argue that the surface of a topological insulator with three degenerate Dirac cones, such as the (111) surface of SmB6, can support pair-density-wave transitions at which a different type of supersymmetry emerges. By mirror symmetry, a duality of supersymmetric theories similar to particle-vortex duality, this novel critical point is dual to supersymmetric quantum electrodynamics, a theory of bosonic and fermionic matter fields interacting with dynamical gauge bosons and fermionic gauginos.