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arXiv · 1807.09781

Higher Order Bosonic Topological Phases in Spin Models

Oleg Dubinkin·Taylor L. Hughes
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Abstract

We discuss an extension of higher order topological phases to include bosonic systems. We present two spin models for a second-order topological phase protected by a global $\mathbb{Z}_2\times\mathbb{Z}_2$ symmetry. One model is built from layers of an exactly solvable cluster model for a one-dimensional $\mathbb{Z}_2\times\mathbb{Z}_2$ topological phase, while the other is built from more conventional spin-couplings (XY or Heisenberg). These models host gapped, but topological, edges, and protected corner modes that fall into a projective representation of the symmetry. Using Jordan-Wigner transformations we show that our models are both related to a bilayer of free Majorana fermions that form a fermionic second-order topological phase. We also discuss how our models can be extended to three-dimensions to form a third-order topological phase.

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Oleg Dubinkin, Taylor L. Hughes. 2018-09-13. Higher Order Bosonic Topological Phases in Spin Models. https://doi.org/10.1103/physrevb.99.235132

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