近日，重庆大学胡自翔团队研究了非厄米Jaynes-Cummings三角形中的高阶异常线。相关论文于2025年10月15日发表在《物理评论A》杂志上。
非厄米系统中的高阶异常点（EPs）表现出多种物理现象，但需要更多的参数空间自由度或对称性。
研究组报道了Jaynes-Cummings三角形中三阶异常曲面和异常线的观测结果。一个微调的人工磁场丰富了三阶异常线（ELs）的出现，当奇偶时间（PT）对称性保护时，它只需要三个调谐参数。三阶EPs通过立方根响应机制保持较强的灵敏度，表现出比二阶EPs更高的灵敏度。研究组开发了一种基于双正交相关状态方法的非平凡保真度度量，该度量可靠地检测EPs，同时消除了先前方法中的非物理保真度值。此外，他们的方法捕获了跨EPs的淬火动力学，揭示了PT对称和PT破缺状态下的不同行为。该工作为研究光-物质相互作用应用于电路QED中的高阶几何建立了一个平台。
附：英文原文
Title: Higher-order exceptional lines in a non-Hermitian Jaynes-Cummings triangle
Author: Hao Chen, Xiao Qin, Jian-Jun Dong, Yu-Yu Zhang, Zi-Xiang Hu
Issue&Volume: 2025/10/15
Abstract: Higher-order exceptional points (EPs) in non-Hermitian systems showcase diverse physical phenomena but require more parameter space freedom or symmetries. We report the observation of a third-order exceptional surface and line in a Jaynes-Cummings triangle. A fine-tuning artificial magnetic field enriches the emergence of the third-order exceptional lines (ELs), which require only three tuning parameters when protected by parity-time (PT) symmetry. Third-order ELs maintain robust enhanced sensitivity through a cube-root response mechanism, displaying a greater sensitivity than second-order EPs. We develop a nontrivial fidelity metric based on the biorthogonal associated-state approach that reliably detects EPs while eliminating the unphysical fidelity values in previous approaches. Furthermore, our method captures quench dynamics across EPs, revealing distinct behavior in both PT-symmetric and PT-broken regimes. Our work establishes a platform for studying higher-order geometry in light-matter interactions using circuit QED.
DOI: 10.1103/t49b-s4fs
Source: https://journals.aps.org/pra/abstract/10.1103/t49b-s4fs