Open systems possess unique potentials in high-precision sensing, yet the majority of previous studies rely on the spectral singularities known as “exceptional points.” Here, we theoretically propose and experimentally demonstrate universal non-Hermitian sensing in the absence of exceptional points. The scheme makes use of the intrinsic sensitivity of a non-Hermitian probe to weak external fields, which can be understood as the direct consequence of non-Hermiticity. We confirm the basic mechanism by simulating the sensor-field dynamics using photon interferometry, and, as a concrete example, demonstrate the enhanced sensing of signals encoded in the setting angle of a wave plate. While the sensitivity of the probe is ultimately limited by the measurement noise, we find the non-Hermitian sensor showing superior performance under background noises that cannot be suppressed through repetitive measurements. Our experiment opens the avenue of enhanced sensing without exceptional points, complementing existing efforts aimed at harnessing the unique features of open systems.

中文翻译：

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无异常点时的非厄米特感应


开放系统在高精度传感方面具有独特的潜力，但以前的大多数研究都依赖于被称为“异常点”的光谱奇点。在这里，我们从理论上提出并实验证明了在没有异常点的情况下普遍的非厄米特传感。该方案利用了非厄米探针对弱外部场的内在敏感性，这可以理解为非厄米特性的直接结果。我们通过使用光子干涉测量法模拟传感器场动力学来确认基本机制，并作为一个具体示例，演示了对以波片设定角度编码的信号的增强感知。虽然探头的灵敏度最终受到测量噪声的限制，但我们发现非厄米特传感器在无法通过重复测量抑制的背景噪声下表现出卓越的性能。我们的实验开辟了没有特殊点的增强传感途径，补充了旨在利用开放系统独特功能的现有努力。