title: Anomalous Quasiparticle Symmetries and Non-Abelian Defects on Symmetrically Gapped Surfaces of Weak Topological Insulators.
abstract: We show that boundaries of 3D weak topological insulators can become gapped by strong interactions while preserving all symmetries, leading to Abelian surface topological order. The anomalous nature of weak topological insulator surfaces manifests itself in a nontrivial action of symmetries on the quasiparticles; most strikingly, translations change the anyon types in a manner impossible in strictly 2D systems with the same symmetry. As a further consequence, screw dislocations form non-Abelian defects that trap Z_{4} parafermion zero modes.
authors: Department of Physics and Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA.
authors: David F
authors: DF
authors: Mross
authors: Department of Physics and Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA.
authors: Andrew
authors: A
authors: Essin
authors: Department of Physics and Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA.|Walter Burke Institute for Theoretical Physics, California Institute of Technology, Pasadena, California 91125, USA.
authors: Jason
authors: J
authors: Alicea
authors: Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel.
authors: Ady
authors: A
authors: Stern