%A Liping Hao(郝丽萍), Yongmei Xue(薛咏梅), Jiabei Fan(樊佳蓓), Jingxu Bai(白景旭), Yuechun Jiao(焦月春), Jianming Zhao(赵建明) %T Precise measurement of a weak radio frequency electric field using a resonant atomic probe %0 Journal Article %D 2020 %J Chin. Phys. B %R 10.1088/1674-1056/ab6c49 %P 33201-033201 %V 29 %N 3 %U {https://cpb.iphy.ac.cn/CN/abstract/article_122293.shtml} %8 2020-03-05 %X We present a precise measurement of a weak radio frequency electric field with a frequency of ≤3 GHz employing a resonant atomic probe that is constituted with a Rydberg cascade three-level atom, including a cesium ground state |6S1/2>, an excited state |6P3/2>, and Rydberg state |nD5/2>. Two radio frequency (RF) electric fields, noted as local and signal fields, couple the nearby Rydberg transition. The two-photon resonant Rydberg electromagnetically induced transparency (Rydberg-EIT) is employed to directly read out the weak signal field having hundreds of kHz difference between the local and signal fields that is encoded in the resonant microwave-dressed Rydberg atoms. The minimum detectable signal fields of ESmin=1.36 ±0.04 mV/m for 2.18 GHz coupling |68D5/2>→|69P3/2> transition and 1.33±0.02 mV/m for 1.32 GHz coupling |80D5/2>→|81P3/2> transition are obtained, respectively. The bandwidth dependence is also investigated by varying the signal field frequency and corresponding -3 dB bandwidth of 3 MHz is attained. This method can be employed to perform a rapid and precise measurement of the weak electric field, which is important for the atom-based microwave metrology.