High-Sensitivity Rydberg Atom-Based Field Sensing Enhancement Using Miniaturized Resonator

High-sensitivity amplitude and frequency detection of microwave electric fields is of significant importance in various fields, including communications, microwave quantum technology, aerospace, medicine, and meteorology. Rydberg atom-based sensors promise traceable standards and high sensitivity for detecting weak electric fields and enhancing sensing sensitivity, by mainly using superheterodyne technology and resonant structures. Detecting high frequency (HF) band fields with high sensitivity using Rydberg atom sensors is a significant challenge due to the requirement of exciting atoms to extremely high energy states for resonant detection. We demonstrate the off-resonant Rydberg atomic superheterodyne architecture with additional resonators for greatly enhancing the sensing sensitivity to HF band fields. In this approach, we propose a miniaturized square spiral resonator with an electrical size of 0.011 λ at 15.54 MHz. To reduce the electric-field-screening effect of the adsorption of alkali-metal atoms, we use a mono-crystalline sapphire cesium-(Cs) vapor cell. By utilizing the off-resonant AC Stark effect, the initial sensitivity of the Rydberg atom sensor without the resonator is measured to be 10.39 μV/cm √ Hz at room temperature. With the addition of the miniaturized square spiral resonator, the sensitivity significantly improved to 2.60 nV/cm √ Hz, which has been inaccessible so far with atomic sensors. Here, we provide an enhancement of 72 dB, which is three-orders of magnitude improvement in sensitivity than when the resonator is not used. This enhancement resonator extends Rydberg atomic high-sensitivity sensing to HF band, and shows great potential, especially in shortwave radio reception.