A Design of Wideband Resonator for Rydberg Atomic Receivers

This paper presents a wideband resonator design for integration with Rydberg atomic receivers, achieving a 14.8 dB enhancement in microwave electric field measurement over the 2.1–3.9 GHz frequency range. The proposed approach flexibly combines metallic parallel plates to form a transmission-line-based structure, which behaves as a second order LC resonant circuit. By optimizing the series and parallel sections, maximum bandwidth is achieved, while the operating band can be adjusted across 1–8 GHz by tuning geometric parameters such as plate length. In contrast to conventional narrowband or mechanically tunable resonators, the proposed design provides stable electric field gain over a broad frequency range without requiring mechanical reconfiguration, making it suitable for various types of Rydberg atomic receivers. The design method is also applicable to vapor cells of different sizes while maintaining similar wideband characteristics. Based on this approach, two resonators operating at different frequencies were fabricated and integrated with a Rydberg atomic sensor. Experimental validation was performed using the AC-Stark effect in cesium atoms excited to the 44D5/2 Rydberg state. Measured results demonstrate a gain of 14.8 dB with a 1.8 GHz bandwidth centered at 3.3 GHz, and 16.8 dB gain with 0.9 GHzbandwidth at 2.05 GHz, confirming the effectiveness of the proposed design methodology.