Exactly soluble model of boundary degeneracy

Sriram Ganeshan, Alexey V. Gorshkov, Victor Gurarie, Victor M. Galitski

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4 Citations (Scopus)


We investigate the topological degeneracy that can be realized in Abelian fractional quantum spin Hall states with multiply connected gapped boundaries. Such a topological degeneracy (also dubbed as "boundary degeneracy") does not require superconducting proximity effect and can be created by simply applying a depletion gate to the quantum spin Hall material and using a generic spin-mixing term (e.g., due to backscattering) to gap out the edge modes. We construct an exactly soluble microscopic model manifesting this topological degeneracy and solve it using the recently developed technique [S. Ganeshan and M. Levin, Phys. Rev. B 93, 075118 (2016)2469-995010.1103/PhysRevB.93.075118]. The corresponding string operators spanning this degeneracy are explicitly calculated. It is argued that the proposed scheme is experimentally reasonable.

Original languageEnglish
Article number045309
Number of pages7
JournalPhysical Review B
Issue number4
Publication statusPublished - 25 Jan 2017

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