PT-symmetric Non-Hermitian Hopf Metal
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arXiv
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| Auteurs principaux: | , , , |
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| Format: | Preprint |
| Publié: |
2023
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| _version_ | 1866915255491231744 |
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| author | Pak, Seik Yeom, Cheol Hun Verma, Sonu Park, Moon Jip |
| author_facet | Pak, Seik Yeom, Cheol Hun Verma, Sonu Park, Moon Jip |
| contents | Hopf insulator is a representative class of three-dimensional topological insulators beyond the standard topological classification methods based on K-theory. In this letter, we discover the metallic counterpart of the Hopf insulator in the non-Hermitian systems. While the Hopf invariant is not a stable topological index due to the additional non-Hermitian degree of freedom, we show that the PT-symmetry stabilizes the Hopf invariant even in the presence of the non-Hermiticity. In sharp contrast to the Hopf insulator phase in the Hermitian counterpart, we discover an interesting result that the non-Hermitian Hopf bundle exhibits the topologically protected non-Hermitian degeneracy, characterized by the two-dimensional surface of exceptional points. Despite the non-Hermiticity, the Hopf metal has the quantized Zak phase, which results in bulk-boundary correspondence by showing drumhead-like surface states at the boundary. Finally, we show that, by breaking PT-symmetry, the nodal surface deforms into the knotted exceptional lines. Our discovery of the Hopf metal phase firstly confirms the existence of the non-Hermitian topological phase outside the framework of the standard topological classifications. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2311_02155 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | PT-symmetric Non-Hermitian Hopf Metal Pak, Seik Yeom, Cheol Hun Verma, Sonu Park, Moon Jip Mesoscale and Nanoscale Physics Quantum Physics Hopf insulator is a representative class of three-dimensional topological insulators beyond the standard topological classification methods based on K-theory. In this letter, we discover the metallic counterpart of the Hopf insulator in the non-Hermitian systems. While the Hopf invariant is not a stable topological index due to the additional non-Hermitian degree of freedom, we show that the PT-symmetry stabilizes the Hopf invariant even in the presence of the non-Hermiticity. In sharp contrast to the Hopf insulator phase in the Hermitian counterpart, we discover an interesting result that the non-Hermitian Hopf bundle exhibits the topologically protected non-Hermitian degeneracy, characterized by the two-dimensional surface of exceptional points. Despite the non-Hermiticity, the Hopf metal has the quantized Zak phase, which results in bulk-boundary correspondence by showing drumhead-like surface states at the boundary. Finally, we show that, by breaking PT-symmetry, the nodal surface deforms into the knotted exceptional lines. Our discovery of the Hopf metal phase firstly confirms the existence of the non-Hermitian topological phase outside the framework of the standard topological classifications. |
| title | PT-symmetric Non-Hermitian Hopf Metal |
| topic | Mesoscale and Nanoscale Physics Quantum Physics |
| url | https://arxiv.org/abs/2311.02155 |