Arxiv Selection Nov 2018

Nov 1-Nov 7 Ahmet Keles, Nov 8-Nov 14 Haiping Hu, Nov 15-Nov 21 Biao Huang, Nov 22- Nov 28 Xuguang Yue

Nov. 12

arXiv:1811.01977
Classification of Crystalline Topological Insulators and Superconductors with Point Group Symmetries
Eyal Cornfeld, Adam Chapman
Crystalline topological phases have recently attracted a lot of experimental and theoretical attention. Key advances include the complete elementary band representation analyses of crystalline matter by symmetry indicators and the discovery of higher order hinge and corner states. However, current classification schemes of such phases are either implicit or limited in scope. We present a new scheme for the explicit classification of crystalline topological insulators and superconductors. These phases are protected by crystallographic point group symmetries and are characterized by bulk topological invariants. The classification paradigm generalizes the Clifford algebra extension process of each Altland-Zirnbauer symmetry class and utilizes algebras which incorporate the point group symmetry. Explicit results for all point group symmetries of 3 dimensional crystals are presented as well as for all symmorphic layer groups of 2 dimensional crystals. We discuss future extensions for treatment of magnetic crystals and defected or higher dimensional systems as well as weak and fragile invariants.

Nov. 13

arXiv:1811.04474
Emergent supersymmetry in a chain of Majorana Cooper pair boxes
Hiromi Ebisu, Eran Sagi, Yuval Oreg
The charging energy of a small superconducting island containing Majorana zero modes - a Majorana Cooper-pair box - induces interactions between the Majorana zero modes. In this manuscript, we investigate a chain of Majorana Cooper-pair boxes, and theoretically demonstrate the emergence of supersymmetry in the strong charging energy regime. A mapping between the Majorana zero modes and spin-1 degrees of freedom results in an effective Blume-Capel model, known for exhibiting an emergent supersymmetry at a non-trivial critical point with central charge c=7/10. We corroborate our findings by mapping the chain to a supersymmetric low energy field theory, exhibiting the same central charge at criticality. The microscopic model we propose consists of local tunneling of Majorana zero modes and local charging energy terms, which can be controlled by gate potentials, thus making its realization more feasible.