Unconventional topological edge states in one-dimensional gapless systems stemming from nonisolated hypersurface singularities
Fuente:
arXiv
Guardado en:
| Autores principales: | , , , , , , , , , |
|---|---|
| Formato: | Preprint |
| Publicado: |
2025
|
| Materias: | |
| Acceso en línea: | |
| Etiquetas: |
Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
|
| _version_ | 1866910859534532608 |
|---|---|
| author | Jia, Hongwei Hu, Jing Zhang, Ruo-Yang Xiao, Yixin Wang, Dongyang Wang, Mudi Ma, Shaojie Ouyang, Xiaoping Zhu, Yifei Chan, C. T. |
| author_facet | Jia, Hongwei Hu, Jing Zhang, Ruo-Yang Xiao, Yixin Wang, Dongyang Wang, Mudi Ma, Shaojie Ouyang, Xiaoping Zhu, Yifei Chan, C. T. |
| contents | Topologically protected edge states have been extensively studied in systems characterized by the topological invariants in band gaps (also called line gaps). In this study, we unveil a whole new form of edge states that transcends the established paradigms of band-gap topology. In contrast to the traditional stable edge states in topological insulators with specific band gaps, the one-dimensional systems we investigate are inherently gapless with the Brillouin zones being mapped to the loops encircling hypersurface singularities in a higher-dimensional space with parity-time symmetry. These hypersurface singularities are nonisolated degeneracies embedded entirely on exceptional surfaces, rendering the energy gaps in our systems inevitably closed at the intersections of the Brillouin zone loop and the exceptional surfaces. Unexpectedly, such gapless systems still afford topologically protected edge states at system boundaries, challenging the conventional understanding based on band gaps. To elucidate the existence of these edge states in the absence of a band-gap-based invariant, we propose a theoretical framework based on eigen-frame rotation and deformation that incorporates non-Bloch band theory. Finally, we experimentally demonstrate this new form of topological edge states with nonreciprocal circuits for the first time. Our work constitutes a major advance that extends topological edge states from gapped phases to gapless phases, offering new insights into topological phenomena. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_03314 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Unconventional topological edge states in one-dimensional gapless systems stemming from nonisolated hypersurface singularities Jia, Hongwei Hu, Jing Zhang, Ruo-Yang Xiao, Yixin Wang, Dongyang Wang, Mudi Ma, Shaojie Ouyang, Xiaoping Zhu, Yifei Chan, C. T. Mesoscale and Nanoscale Physics Topologically protected edge states have been extensively studied in systems characterized by the topological invariants in band gaps (also called line gaps). In this study, we unveil a whole new form of edge states that transcends the established paradigms of band-gap topology. In contrast to the traditional stable edge states in topological insulators with specific band gaps, the one-dimensional systems we investigate are inherently gapless with the Brillouin zones being mapped to the loops encircling hypersurface singularities in a higher-dimensional space with parity-time symmetry. These hypersurface singularities are nonisolated degeneracies embedded entirely on exceptional surfaces, rendering the energy gaps in our systems inevitably closed at the intersections of the Brillouin zone loop and the exceptional surfaces. Unexpectedly, such gapless systems still afford topologically protected edge states at system boundaries, challenging the conventional understanding based on band gaps. To elucidate the existence of these edge states in the absence of a band-gap-based invariant, we propose a theoretical framework based on eigen-frame rotation and deformation that incorporates non-Bloch band theory. Finally, we experimentally demonstrate this new form of topological edge states with nonreciprocal circuits for the first time. Our work constitutes a major advance that extends topological edge states from gapped phases to gapless phases, offering new insights into topological phenomena. |
| title | Unconventional topological edge states in one-dimensional gapless systems stemming from nonisolated hypersurface singularities |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2503.03314 |