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  • Letter
  • Open Access

Classification of exceptional nodal topologies protected by PT symmetry

Marcus Stålhammar and Emil J. Bergholtz

  • Department of Physics, Stockholm University, AlbaNova University Center, 106 91 Stockholm, Sweden

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Phys. Rev. B 104, L201104 – Published 10 November, 2021

DOI: https://doi.org/10.1103/PhysRevB.104.L201104

Abstract

Exceptional degeneracies, at which both eigenvalues and eigenvectors coalesce, and parity-time (PT) symmetry, reflecting balanced gain and loss in photonic systems, are paramount concepts in non-Hermitian systems. We here complete the topological classification of exceptional nodal degeneracies protected by PT symmetry in up to three dimensions and provide simple example models whose exceptional nodal topologies include previously overlooked possibilities such as second-order knotted surfaces of arbitrary genus, third-order knots, and fourth-order points.

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Phys. Rev. B 104, L201104– Published 10 November, 2021
  • Received 12 June 2021
  • Revised 30 August 2021
  • Accepted 25 October 2021
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by Bibsam.

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