# Criteria for protected edge modes with Z2 symmetry

@article{Heinrich2018CriteriaFP, title={Criteria for protected edge modes with Z2 symmetry}, author={Chris Heinrich and Michael A. Levin}, journal={Physical Review B}, year={2018} }

We derive a necessary and sufficient criterion for when a two dimensional gapped many-body system with Abelian anyons and a unitary $\mathbb{Z}_2$ symmetry has a protected gapless edge mode. Our criterion is phrased in terms of edge theories --- or more specifically, chiral boson edge theories with $\mathbb{Z}_2$ symmetry --- and it applies to any bosonic or fermionic system whose boundary can be described by such an edge theory. At an operational level, our criterion takes as input a chiral…

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