Nonlinear Quantum Sensing of High-Frequency Statistical Fluctuations of the Fine-Structure Constant

The fine-structure constant is usually regarded as a static fundamental parameter. Two recent independent experimental studies [4,5] have examined this notion from different perspectives. Building on this, we take a quantum sensing approach and treat a Rydberg EIT‑AT system as a nonlinear detector to probe possible high‑frequency statistical fluctuations of . We establish a theoretical framework that includes atom‑light nonlinear response and analyze how high‑order statistical features of squeezed light are converted into observable variance of frequency readings via the nonlinear response. Based on this framework, we propose a testable experimental prediction: there exists a squeezing parameter threshold such that, for and with the system operating in the regime, the frequency variance after subtracting shot noise under squeezed light exceeds that under coherent light. This prediction does not depend on the specific microscopic model of fluctuations, but assumes a macroscopic correlation length for (as a working hypothesis). It should be noted that the current estimate shows the required squeezing parameter lies beyond the present experimental capability (); thus the core positioning of this work is to propose a future detection direction and specify its technical requirements, rather than a near‑term realizable scheme. Notably, the recent experiment by Chao, You et al. [4] provides independent experimental evidence for the tunability of the key nonlinear parameter of this work. This paper aims to offer a possible theoretical reference framework for detecting high‑frequency fluctuations of fundamental constants. Keywords: fine‑structure constant; squeezed light; Rydberg atoms; non‑Gaussian fluctuations; quantum sensing; phenomenological model 摘要 精细结构常数 通常被视为一个静态的基本参数。近期两项独立的实验研究[4,5]