Quantum Measurement of Radio-Frequency Attenuation Based on Atomic Resonance

In this study, a quantum measurement method of radio-frequency (RF) attenuation based on atomic resonance is realized for the first time utilizing the interaction among atoms and RF waves. In the experiments, cesium-133 (133Cs) atoms in a rectangular cell inserted in a WR-90 waveguide were simultaneously irradiated with a 9.2-GHz RF wave and an 852-nm wavelength laser. First, double-resonance (DR) spectroscopy of the RF waves and laser was performed, and the magnitude and time constant of the DR signals were compared with the attenuation. Subsequently, the Rabi frequency of cesium atoms was measured using an atomic candle method. Results reveal that the Rabi frequency is proportional to the relative RF magnetic field strength. Moreover, the best linearity (up to 35 dB) was obtained for the Rabi frequency-derived attenuation. This study is expected to contribute to the development of RF precision measurement techniques for communication technologies, such as 5G/beyond 5G and electromagnetic compatibility evaluations, as well as to realize the next-generation RF power and attenuation standards based on quantum phenomena.