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SUMMARY:Non-Hermitian Topology in Hermitian Topological Matter
DTSTART:20261006T053000Z
DTEND:20261006T073000Z
DTSTAMP:20261015T060000Z
UID:indico-event-217@indico.phys.nthu.edu.tw
DESCRIPTION:Speakers: Kohei Kawabata[川畑幸平] (ISSP\, University of T
 okyo)\n\nAbstract:\nNon-Hermiticity gives rise to distinctive topological 
 phenomena absent in Hermitian systems. However\, connection between such i
 ntrinsic non-Hermitian topology and Hermitian topology has remained largel
 y elusive. Here\, considering the bulk and boundary as an environment and 
 system\, we demonstrate that anomalous boundary states in Hermitian topolo
 gical insulators exhibit non-Hermitian topology [1\, 2]. We study the self
 -energy capturing the particle exchange between the bulk and boundary\, an
 d show that it detects Hermitian topology in the bulk and induces non-Herm
 itian topology at the boundary. As an illustrative example\, we reveal the
  non-Hermitian topology and concomitant skin effect inherently embedded wi
 thin chiral edge states of Chern insulators. We also identify the emergenc
 e of hinge states within effective non-Hermitian Hamiltonians at surfaces 
 of three-dimensional topological insulators. Furthermore\, we comprehensiv
 ely classify our correspondence across all the tenfold symmetry classes of
  topological insulators and superconductors.\nBased on this correspondence
  and K-theory\, we complete the tenfold classification of Wannier localiza
 bility and detachable topological boundary states [3\, 4]. While topology 
 can impose obstructions to exponentially localized Wannier functions\, cer
 tain topological insulators are exempt from such Wannier obstructions. The
  absence of the Wannier obstructions can further accompany topological bou
 ndary states that are detachable from the bulk bands. Here\, we elucidate 
 a close connection between these detachable topological boundary states an
 d non-Hermitian topology. Identifying topological boundary states as non-H
 ermitian topology\, we demonstrate that intrinsic non-Hermitian topology l
 eads to the inevitable spectral flow. By contrast\, we show that extrinsic
  non-Hermitian topology underlies the detachment of topological boundary s
 tates and clarify anti-Hermitian topology of the detached boundary states.
 \nReferences\n\n[1] F. Schindler\, K. Gu\, B. Lian\, and K. Kawabata\, PRX
  Quantum 4\, 030315 (2023).\n[2] S. Hamanaka\, T. Yoshida\, and K. Kawabat
 a\, Phys. Rev. Lett. 133\, 266604 (2024).\n[3] D. Nakamura\, K. Shiozaki\,
  K. Shimomura\, M. Sato\, and K. Kawabata\, Phys. Rev. Lett. 135\, 096601 
 (2025).\n[4] K. Shiozaki\, D. Nakamura\, K. Shimomura\, M. Sato\, and K. K
 awabata\, Phys. Rev. B 112\, 075152 (2025).\n\n\nhttps://indico.phys.nthu.
 edu.tw/event/217/
LOCATION:Physics/019 (NTHU)
URL:https://indico.phys.nthu.edu.tw/event/217/
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