Exceptional topology on nonorientable manifolds
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g5cr-dwxz.pdf
Description
Published version
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1011.6 KB
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Author(s)
König, J Lukas K
Yang, Kang
Fonseca, André Grossi
Vaidya, Sachin
Soljačić, Marin
Bergholtz, Emil J
Date Issued
March 3, 2026
Journal
Physical Review Research
Publisher
American Physical Society (APS)
Citation
König, J Lukas K, Yang, Kang, Fonseca, André Grossi, Vaidya, Sachin, Soljačić, Marin et al. 2026. "Exceptional topology on nonorientable manifolds." Physical Review Research, 8 (1).
Version
Final published version
Abstract
We classify gapped phases and characteristic nodal points of non-Hermitian band structures on two-dimensional nonorientable parameter spaces. Such spaces arise in a wide range of physical systems in the presence of nonsymmorphic parameter space symmetries. For gapped phases, we find that nonorientable spaces provide a natural setting for exploring fundamental structural problems in braid group theory, such as torsion and conjugacy. Gapless systems, which host exceptional points (EPs), explicitly violate fermion doubling, even in two-band models. We demonstrate that EPs traversing the nonorientable parameter space exhibit non-Abelian charge inversion. These braided phases and their transitions leave distinct signatures in the form of bulk Fermi arc degeneracies, offering a concrete route toward experimental realization and verification.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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Creative Commons Attribution
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DOI of Published Version
https://doi.org/10.1103/g5cr-dwxz
