Topological invariant of non-Hermitian space-time modulated photonic crystals
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arXiv
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| Autores principales: | , , , , |
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| Formato: | Preprint |
| Publicado: |
2024
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| _version_ | 1866913629179215872 |
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| author | Gao, Xiaoke Zhao, Xiaoyu Wang, Jiawei Ma, Xikui Dong, Tianyu |
| author_facet | Gao, Xiaoke Zhao, Xiaoyu Wang, Jiawei Ma, Xikui Dong, Tianyu |
| contents | We propose a medium transformation approach to formulate the adjoint system of space-time modulated photonic crystals (STMPCs), essential for the bi-orthogonal Berry connection when calculating the topological invariant. We show that the non-Abelian Zak phase of STMPCs comprising stacked photonic time crystals and dielectrics is quantized to 0 or 1 for both the entangled and isolated bands. We find that the eigenmodes at the center and edge of the Brillouin zone differ in symmetry for the band with non-trivial Zak phases, while they share the same symmetry for the trivial Zak phases. In addition, topological phase transitions owing to band inversion are observed. Moreover, a generalized Brillouin zone of the non-Hermitian STMPCs is established, which is identical to the Hermitian counterpart, implicating that the non-Bloch band theory is not required in this regard. The proposed medium transformation method may serve as an alternative approach to exploring more intricate topological phenomena in non-Hermitian systems when incorporating non-Bloch band theory. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2412_20636 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Topological invariant of non-Hermitian space-time modulated photonic crystals Gao, Xiaoke Zhao, Xiaoyu Wang, Jiawei Ma, Xikui Dong, Tianyu Optics We propose a medium transformation approach to formulate the adjoint system of space-time modulated photonic crystals (STMPCs), essential for the bi-orthogonal Berry connection when calculating the topological invariant. We show that the non-Abelian Zak phase of STMPCs comprising stacked photonic time crystals and dielectrics is quantized to 0 or 1 for both the entangled and isolated bands. We find that the eigenmodes at the center and edge of the Brillouin zone differ in symmetry for the band with non-trivial Zak phases, while they share the same symmetry for the trivial Zak phases. In addition, topological phase transitions owing to band inversion are observed. Moreover, a generalized Brillouin zone of the non-Hermitian STMPCs is established, which is identical to the Hermitian counterpart, implicating that the non-Bloch band theory is not required in this regard. The proposed medium transformation method may serve as an alternative approach to exploring more intricate topological phenomena in non-Hermitian systems when incorporating non-Bloch band theory. |
| title | Topological invariant of non-Hermitian space-time modulated photonic crystals |
| topic | Optics |
| url | https://arxiv.org/abs/2412.20636 |