Exceptional nexus with a hybrid topological invariant.
Journal
Science (New York, N.Y.)
ISSN: 1095-9203
Titre abrégé: Science
Pays: United States
ID NLM: 0404511
Informations de publication
Date de publication:
27 11 2020
27 11 2020
Historique:
received:
17
07
2020
accepted:
13
10
2020
entrez:
27
11
2020
pubmed:
28
11
2020
medline:
28
11
2020
Statut:
ppublish
Résumé
Branch-point singularities known as exceptional points (EPs), which carry a nonzero topological charge, can emerge in non-Hermitian systems. We demonstrate with both theory and acoustic experiments an "exceptional nexus" (EX), which is not only a higher-order EP but also the cusp singularity of multiple exceptional arcs (EAs). Because the parameter space is segmented by the EAs, the EX possesses a hybrid topological invariant (HTI), which consists of distinct winding numbers associated with Berry phases accumulated by cyclic paths on different complex planes. The HTI is experimentally characterized by measuring the critical behaviors of the wave functions. Our findings constitute a major advance in the fundamental understanding of non-Hermitian systems and their topology, possibly opening new avenues for applications.
Identifiants
pubmed: 33243886
pii: 370/6520/1077
doi: 10.1126/science.abd8872
doi:
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
1077-1080Informations de copyright
Copyright © 2020, American Association for the Advancement of Science.