Constraining ultralight dark matter through an accelerated resonant search
Zitong Xu, Xiaolin Ma, Kai Wei, Yuxuan He, Xing Heng, Xiaofei Huang, Tengyu Ai, Jian Liao, Wei Ji, Jia Liu, Xiao-Ping Wang, Dmitry Budker
Abstract
Abstract Typical weak signal search experiments rely on resonant effects, where the resonance frequency is scanned over a broad range, resulting in significant time consumption. In this study, we demonstrate an accelerated strategy that surpasses the typical resonance-bandwidth limited scan step without compromising sensitivity. We apply this method to an alkali-noble-gas spin system, achieving an approximately 30-fold increase in scanning step size. Additionally, we obtain an ultrahigh sensitivity of 1.29 fT ⋅ Hz −1/2 at around 5 Hz, corresponding to an energy resolution of approximately 1.8 × 10 −23 eV ⋅ Hz −1/2 , which is among the highest quantum energy resolutions reported. Furthermore, we use this sensor to search for axion-like particles, setting stringent constraints on axion-like particles (ALPs) in the 4.5–15.5 Hz Compton-frequency range coupling to neutrons and protons, improving on previous limits by several-fold. This accelerated strategy has potential applications in other resonant search experiments.