Synthetically enhanced sensitivity using higher-order exceptional point and coherent perfect absorption

TL;DR

This paper introduces a novel sensor design that combines higher-order exceptional points with coherent perfect absorption in a hybrid non-Hermitian system, significantly boosting sensitivity beyond traditional methods.

Contribution

It demonstrates a synthetic enhancement of sensor sensitivity by integrating CPA with third-order EP in a cavity magnonic system, overcoming complexity issues of higher-order EPs.

Findings

Achieved a minimum detectable magnetic field change of 4.2×10⁻²¹ T.

Utilized spectral anomaly of CPA to enhance sensitivity at third-order EP.

Proposed a new approach for designing highly sensitive sensors using hybrid quantum systems.

Abstract

Sensors play a crucial role in advanced apparatuses and it is persistently pursued to improve their sensitivities. Recently, the singularity of a non-Hermitian system, known as the exceptional point (EP), has drawn much attention for this goal. Response of the eigenfrequency shift to a perturbation $\epsilon$ follows the $\epsilon^{1/n}$-dependence at an $n$th-order EP, leading to significantly enhanced sensitivity via a high-order EP. However, due to the requirement of increasingly complicated systems, great difficulties will occur along the path of increasing the EP order to enhance the sensitivity. Here we report that by utilizing the spectral anomaly of the coherent perfect absorption (CPA), the sensitivity at a third-order EP can be further enhanced owing to the cooperative effects of both CPA and EP. We realize this synthetically enhanced sensor using a pseudo-Hermitian cavity magnonic system composed of two yttrium iron garnet spheres and a microwave cavity. The detectable minimum change of the magnetic field reaches $4.2\times10^{-21}$T. It opens a new avenue to design novel sensors using hybrid non-Hermitian quantum systems.