High-sensitivity electric-field quantum sensing using optimal Rydberg electromagnetically-induced-transparency

Microwave electric fields are a cornerstone of modern technologies, ranging from data communications to remote sensing. Consequently, the precise measurement and analysis of their properties are essential. Rydberg atoms, with their high electrical polarizability and strong transition dipole moments, are highly suitable for quantifying microwave field strengths with high sensitivity. In this study, we demonstrate high-sensitivity electric field sensing using the 5S_1/2-5P_3/2-40D_5/2-39F_7/2 energy transition scheme in ⁸⁵Rb atoms. To ensure measurement stability and precision, we employed an ultra-low expansion (ULE) cavity for laser frequency stabilization. We specifically investigated the dependence of the observable microwave field strength on the electromagnetically induced transparency (EIT) linewidth. By employing an atomic heterodyne technique and optimizing both the EIT linewidth and RF polarization, we achieved a sensitivity of 13.3 nV/cm√Hz. These results provide a significant foundation for the development of low-noise, high-sensitivity quantum sensors for RF electric field metrology.