Rydberg atomic field-enhanced feed beyond electrically small antennas

Abstract

The reception of electromagnetic signals becomes increasingly challenging at longer wavelengths, as conventional antenna feeds must scale with the operating wavelength, making it difficult to reconcile compactness with high sensitivity. Rydberg atoms enable direct field-to-optical conversion within deeply subwavelength sensing volumes, yet an effective receiving feed that couples incident fields into the atomic interaction volume remains underdeveloped. Here, we introduce a Rydberg atomic field-enhanced feed (RAFEF) that integrates electromagnetic field capture and enhancement with Rydberg-atomic transduction. We establish a physical model to quantify its receiving capability, Phi, that jointly accounts for sensitivity enhancement, receiving bandwidth and normalized three-dimensional volume, and experimentally obtain Phi_dB = 70.81 dB. Compared with a conventional loop-antenna feed, the RAFEF provides a higher received SNR and overall receiving capability, while its tunable narrowband response enables frequency selectivity directly at the receiving-feed stage. We further demonstrate selective recovery of a target channel from simultaneously incident signals and reception of a 93.5 MHz FM broadcast after approximately 10 km of over-the-air propagation. These results establish the RAFEF as an atomic receiving-feed architecture that exploits localized electric-field transduction to extend Rydberg-atomic reception beyond conventional electrically small antenna feeds.