Fig. 1. Experimental setup and energy level diagram of Rydberg ladder EIT system. (a) Schematic of the experimental setup; (b) diagram of energy level

Fig. 2. EIT spectra under the variation electric strength. (a) E=0 V/cm; (b) E=0.3 V/cm; (c) E=0.52 V/cm

Fig. 3. Frequency shift of hyperfine states in EIT spectra varying with electric field strength of RF fields

Fig. 4. EIT signal under the power-frequency electric field with different frequency. (a) 45 Hz; (b) 50 Hz; (c) 55 Hz

Fig. 5. Modulated frequency versus measured frequency of power-frequency field