近日，美国加州理工学院的Alireza Marandi及其研究团队取得一项新进展。他们成功通过非厄米拓扑增强了灵敏度。相关研究成果已于2025年1月1日在国际知名学术期刊《光：科学与应用》上发表。

该研究团队利用由光脉冲表示的合成维度中的光子时间复用谐振器网络，实验性演示了非厄米拓扑传感器（NTOS）。通过精心编程设置该网络中的延迟线，研究人员实现了非厄米拓扑传感方案中的典型Hatano-Nelson模型。研究人员对不同晶格尺寸进行实验测量，所得灵敏度结果证实了NTOS具有的特征性指数级增强。

研究表明，这种独特的响应源于非厄米性与拓扑性的协同作用，这是厄米拓扑晶格中所不具备的。研究人员对NTOS的实验演示为实现前所未有的高灵敏度传感器开辟了道路。

据悉，传感器是现代生活中不可或缺的工具，广泛应用于从智能手机、自动驾驶汽车到医疗保健行业和空间技术的各个领域。通过连接多个传感器，使它们共同与被测信号相互作用，可以超越单个元件所能达到的信噪比（SNR）。这种技术也已在量子领域得到应用，利用纠缠态实现了信噪比的线性提升。

类似地，耦合非厄米系统通过高阶奇异点提供了额外的自由度，从而能够开发出性能更优的传感器。最近，理论上提出了一种新型非厄米系统，即非厄米拓扑传感器（NTOS）。值得注意的是，非厄米性与拓扑性之间的协同作用有望赋予这种传感器更高的灵敏度，且灵敏度随传感器网络规模的扩大呈指数级增长。

附：英文原文

Title: Enhanced sensitivity via non-Hermitian topology

Author: Parto, Midya, Leefmans, Christian, Williams, James, Gray, Robert M., Marandi, Alireza

Issue&Volume: 2025-01-01

Abstract: Sensors are indispensable tools of modern life that are ubiquitously used in diverse settings ranging from smartphones and autonomous vehicles to the healthcare industry and space technology. By interfacing multiple sensors that collectively interact with the signal to be measured, one can go beyond the signal-to-noise ratios (SNR) attainable by the individual constituting elements. Such techniques have also been implemented in the quantum regime, where a linear increase in the SNR has been achieved via using entangled states. Along similar lines, coupled non-Hermitian systems have provided yet additional degrees of freedom to obtain better sensors via higher-order exceptional points. Quite recently, a new class of non-Hermitian systems, known as non-Hermitian topological sensors (NTOS) has been theoretically proposed. Remarkably, the synergistic interplay between non-Hermiticity and topology is expected to bestow such sensors with an enhanced sensitivity that grows exponentially with the size of the sensor network. Here, we experimentally demonstrate NTOS using a network of photonic time-multiplexed resonators in the synthetic dimension represented by optical pulses. By judiciously programming the delay lines in such a network, we realize the archetypal Hatano-Nelson model for our non-Hermitian topological sensing scheme. Our experimentally measured sensitivities for different lattice sizes confirm the characteristic exponential enhancement of NTOS. We show that this peculiar response arises due to the combined synergy between non-Hermiticity and topology, something that is absent in Hermitian topological lattices. Our demonstration of NTOS paves the way for realizing sensors with unprecedented sensitivities.

DOI: 10.1038/s41377-024-01667-z

Source: https://www.nature.com/articles/s41377-024-01667-z