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| Main Authors: | , , , |
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| Format: | Preprint |
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2024
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| Online Access: | https://arxiv.org/abs/2412.02782 |
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| _version_ | 1866912434686525440 |
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| author | Schoenzeit, Megan Shu, Chang Zhang, Kai Sun, Kai |
| author_facet | Schoenzeit, Megan Shu, Chang Zhang, Kai Sun, Kai |
| contents | Topological semimetals exhibit protected band crossings in momentum space, accompanied by corresponding surface states. Non-Hermitian Hamiltonians introduce geometry-sensitive features that dissolve this bulk-boundary correspondence principle. In this paper, we exemplify this phenomenon by investigating a non-Hermitian 2D stacked SSH chain model with non-reciprocal hopping and on-site gain/loss. We derive an analytical phase diagram in terms of the complex energy gaps in the open-boundary spectrum. The phase diagram reveals the existence of non-Bloch Dirac points, which feature a real spectrum and only appear under open boundary conditions but disappear in Bloch bands under periodic boundary conditions. Due to the reality of the spectrum in the vicinity of non-Bloch Dirac points, we can locally map it to Hermitian semimetals within the Altland-Zirnabuer symmetry classes. Based on this mapping, we demonstrate that non-Bloch Dirac points are characterized by an integer topological charge. Unlike the band crossings in Hermitian semimetals, the locations of the non-Bloch Dirac points under different boundary geometries do not match each other, indicating a geometry-dependent bulk-boundary correspondence in non-Hermitian semimetals. Our findings provide new pathways into establishing unconventional bulk-boundary correspondence for non-Bloch Dirac metals in non-Hermitian systems. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2412_02782 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Non-Bloch Dirac Points and Phase Diagram in the Stacked Non-Hermitian SSH Model Schoenzeit, Megan Shu, Chang Zhang, Kai Sun, Kai Mesoscale and Nanoscale Physics Quantum Gases Topological semimetals exhibit protected band crossings in momentum space, accompanied by corresponding surface states. Non-Hermitian Hamiltonians introduce geometry-sensitive features that dissolve this bulk-boundary correspondence principle. In this paper, we exemplify this phenomenon by investigating a non-Hermitian 2D stacked SSH chain model with non-reciprocal hopping and on-site gain/loss. We derive an analytical phase diagram in terms of the complex energy gaps in the open-boundary spectrum. The phase diagram reveals the existence of non-Bloch Dirac points, which feature a real spectrum and only appear under open boundary conditions but disappear in Bloch bands under periodic boundary conditions. Due to the reality of the spectrum in the vicinity of non-Bloch Dirac points, we can locally map it to Hermitian semimetals within the Altland-Zirnabuer symmetry classes. Based on this mapping, we demonstrate that non-Bloch Dirac points are characterized by an integer topological charge. Unlike the band crossings in Hermitian semimetals, the locations of the non-Bloch Dirac points under different boundary geometries do not match each other, indicating a geometry-dependent bulk-boundary correspondence in non-Hermitian semimetals. Our findings provide new pathways into establishing unconventional bulk-boundary correspondence for non-Bloch Dirac metals in non-Hermitian systems. |
| title | Non-Bloch Dirac Points and Phase Diagram in the Stacked Non-Hermitian SSH Model |
| topic | Mesoscale and Nanoscale Physics Quantum Gases |
| url | https://arxiv.org/abs/2412.02782 |