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- Title
Realization and topological properties of third-order exceptional lines embedded in exceptional surfaces.
- Authors
Tang, Weiyuan; Ding, Kun; Ma, Guancong
- Abstract
As the counterpart of Hermitian nodal structures, the geometry formed by exceptional points (EPs), such as exceptional lines (ELs), entails intriguing spectral topology. We report the experimental realization of order-3 exceptional lines (EL3) that are entirely embedded in order-2 exceptional surfaces (ES2) in a three-dimensional periodic synthetic momentum space. The EL3 and the concomitant ES2, together with the topology of the underlying space, prohibit the evaluation of their topology in the eigenvalue manifold by prevailing topological characterization methods. We use a winding number associated with the resultants of the Hamiltonian. This resultant winding number can be chosen to detect only the EL3 but ignores the ES2, allowing the diagnosis of the topological currents carried by the EL3, which enables the prediction of their evolution under perturbations. We further reveal the connection between the intersection multiplicity of the resultants and the winding of the resultant field around the EPs and generalize the approach for detecting and topologically characterizing higher-order EPs. Our work exemplifies the unprecedented topology of higher-order exceptional geometries and may inspire new non-Hermitian topological applications. The authors report an experimental realization of order-3 exceptional lines (EL3) in a stack of three coupled acoustic cavities. The EL3 are embedded in an order-2 exceptional surface. The authors use the winding number of resultants of the Hamiltonian matrix to diagnose the topology of EL3.
- Subjects
TOPOLOGICAL property; HERMITIAN structures; MOMENTUM space; ACOUSTIC couplers; TOPOLOGY
- Publication
Nature Communications, 2023, Vol 14, Issue 1, p1
- ISSN
2041-1723
- Publication type
Article
- DOI
10.1038/s41467-023-42414-z