# Gapped domain walls, gapped boundaries, and topological degeneracy.

@article{Lan2015GappedDW,
title={Gapped domain walls, gapped boundaries, and topological degeneracy.},
author={Tian Lan and Juven C. Wang and Xiao-Gang Wen},
journal={Physical review letters},
year={2015},
volume={114 7},
pages={
076402
}
}
• Published 27 August 2014
• Physics, Medicine, Mathematics
• Physical review letters
Gapped domain walls, as topological line defects between (2+1)D topologically ordered states, are examined. We provide simple criteria to determine the existence of gapped domain walls, which apply to both Abelian and non-Abelian topological orders. Our criteria also determine which (2+1)D topological orders must have gapless edge modes, namely, which (1+1)D global gravitational anomalies ensure gaplessness. Furthermore, we introduce a new mathematical object, the tunneling matrix W, whose…

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