Non-Hermitian Dirac cones with valley-dependent lifetimes
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arXiv
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| Format: | Preprint |
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2024
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| author | Xie, Xinrong Ma, Fei Rui, W. B. Dong, Zhaozhen Du, Yulin Xie, Wentao Zhao, Y. X. Chen, Hongsheng Gao, Fei Xue, Haoran |
| author_facet | Xie, Xinrong Ma, Fei Rui, W. B. Dong, Zhaozhen Du, Yulin Xie, Wentao Zhao, Y. X. Chen, Hongsheng Gao, Fei Xue, Haoran |
| contents | Relativistic quasiparticles emerging from band degeneracies in crystals play crucial roles in the transport and topological properties of materials and metamaterials. Quasiparticles are commonly described by Hermitian Hamiltonians, with non-Hermiticity usually considered detrimental. In this work, we show that such an assumption of Hermiticity can be lifted to bring quasiparticles into non-Hermitian regime. We propose a concrete lattice model containing two Dirac cones with valley-dependent lifetimes. The lifetime contrast enables an ultra-strong valley selection rule: only one valley can survive in the long-time limit regardless of the excitation, lattice shape and other details. This property leads to an effective parity anomaly with a single Dirac cone and offers a simple way to generate vortex states. Additionally, extending non-Hermitian features to boundaries generates valley kink states with valley-locked lifetimes, making them effectively unidirectional and more resistant against inter-valley scattering. All these phenomena are experimentally demonstrated in a non-Hermitian electric circuit lattice. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2410_06058 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Non-Hermitian Dirac cones with valley-dependent lifetimes Xie, Xinrong Ma, Fei Rui, W. B. Dong, Zhaozhen Du, Yulin Xie, Wentao Zhao, Y. X. Chen, Hongsheng Gao, Fei Xue, Haoran Mesoscale and Nanoscale Physics Applied Physics Relativistic quasiparticles emerging from band degeneracies in crystals play crucial roles in the transport and topological properties of materials and metamaterials. Quasiparticles are commonly described by Hermitian Hamiltonians, with non-Hermiticity usually considered detrimental. In this work, we show that such an assumption of Hermiticity can be lifted to bring quasiparticles into non-Hermitian regime. We propose a concrete lattice model containing two Dirac cones with valley-dependent lifetimes. The lifetime contrast enables an ultra-strong valley selection rule: only one valley can survive in the long-time limit regardless of the excitation, lattice shape and other details. This property leads to an effective parity anomaly with a single Dirac cone and offers a simple way to generate vortex states. Additionally, extending non-Hermitian features to boundaries generates valley kink states with valley-locked lifetimes, making them effectively unidirectional and more resistant against inter-valley scattering. All these phenomena are experimentally demonstrated in a non-Hermitian electric circuit lattice. |
| title | Non-Hermitian Dirac cones with valley-dependent lifetimes |
| topic | Mesoscale and Nanoscale Physics Applied Physics |
| url | https://arxiv.org/abs/2410.06058 |