Rydberg atom receiver enhanced by ENZ-GSP coupling: a theoretical design for quantum sensing

To address the bandwidth limitation and sensitivity bottleneck of Rydberg atom receivers, this paper proposes a hybrid structural design incorporating epsilon-near-zero (ENZ) materials and gap surface plasmon (GSP) coupling. This design achieves subwavelength field localization through the extreme wavevector compression effect of ENZ materials (k/k₀ ≈ 0.01), combined with the broadband strong field confinement characteristics of GSPs. Within the 0.1–40 GHz range, it constructs a broadband electromagnetic field enhancement platform, which can be coupled with the atomic cell of a traditional Rydberg receiver and is expected to enhance the receiver's sensitivity. Theoretical analysis shows that this structure can improve the Rydberg atom transition efficiency, achieving a theoretical sensitivity of -142 dBm/Hz¹/², with an increased bandwidth compared to traditional schemes. The ENZ-GSP coupling structure theoretically has the potential to overcome the existing high sensitivity–broadband trade-off, providing a new direction for weak signal detection in radio astronomy and broadband sensing in next-generation communication systems.