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| Main Authors: | , , , , , , , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2601.17266 |
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| _version_ | 1866914277164580864 |
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| author | Tang, Jiang-Shan Xiao, Long-Qi Wu, Hao-Dong Jing, Yuwei Zhang, Han Ruan, Ya-Ping Liu, Wuming Lu, Yan-Qing Xia, Keyu |
| author_facet | Tang, Jiang-Shan Xiao, Long-Qi Wu, Hao-Dong Jing, Yuwei Zhang, Han Ruan, Ya-Ping Liu, Wuming Lu, Yan-Qing Xia, Keyu |
| contents | A non-Hermitian system at an exceptional point (EP), a specific critical point (CP) associated with the parity-time symmetric phase transition, exhibits a sublinear response to perturbation and promise unprecedented sensitivity beyond the linear-response Hermitian sensors, so far operating at the diabolic points (DP). Despite great advancements, its sensitivity enhancement is fundamentally limited by the divergent Petermann factor, intrinsically rooted in the non-Hermitian eigenvector degeneracy, and practically by the system complexity. Here, we report the CP-resulting square-root response to the refractive index change and enhanced sensitivity in a simple chiral Hermitian cavity without phase transitions. Because of the inherent eigenvector orthogonality, this CP-based Hermitian sensor exhibits an EP-like response and enhanced sensitivity, breaking the Petermann-factor limit of sensitivity in non-Hermitian counterparts. This work paves the way towards exploring the Hermitian CPs for ultrasensitive sensing outperforming both the EP- and DP-based sensors. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2601_17266 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Exceptional-point-like Sensing near Hermitian Critical Points Tang, Jiang-Shan Xiao, Long-Qi Wu, Hao-Dong Jing, Yuwei Zhang, Han Ruan, Ya-Ping Liu, Wuming Lu, Yan-Qing Xia, Keyu Optics A non-Hermitian system at an exceptional point (EP), a specific critical point (CP) associated with the parity-time symmetric phase transition, exhibits a sublinear response to perturbation and promise unprecedented sensitivity beyond the linear-response Hermitian sensors, so far operating at the diabolic points (DP). Despite great advancements, its sensitivity enhancement is fundamentally limited by the divergent Petermann factor, intrinsically rooted in the non-Hermitian eigenvector degeneracy, and practically by the system complexity. Here, we report the CP-resulting square-root response to the refractive index change and enhanced sensitivity in a simple chiral Hermitian cavity without phase transitions. Because of the inherent eigenvector orthogonality, this CP-based Hermitian sensor exhibits an EP-like response and enhanced sensitivity, breaking the Petermann-factor limit of sensitivity in non-Hermitian counterparts. This work paves the way towards exploring the Hermitian CPs for ultrasensitive sensing outperforming both the EP- and DP-based sensors. |
| title | Exceptional-point-like Sensing near Hermitian Critical Points |
| topic | Optics |
| url | https://arxiv.org/abs/2601.17266 |