Exactly soluble model of boundary degeneracy.

  title={Exactly soluble model of boundary degeneracy.},
  author={Sriram Ganeshan and Alexey V. Gorshkov and Victor Gurarie and Victor M. Galitski},
  journal={Physical review. B},
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… 

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