Extending microwave-frequency electric-field detection through single transmission peak method

The strength of microwave (MW) electric field can be observed with high precision by using the standard electromagnetically induced transparency and Aulter–Towns (EIT-AT) technique, when its frequency is resonant or nearly-resonant with the Rydberg transition frequency. As the detuning of MW field increases, one of the transmission peaks (single peak) is easier to measure due to its increased amplitude. It can be found that the central symmetry point of the two transmission peaks f_1/2 is only related to the detuning of MW field Δ_MW and central symmetry point f₀ of resonant MW field, satisfying the relation f_1/2 = Δ_MW/2 + f₀. Thus, we demonstrate a single transmission peak method that the MW E-field can be determined by interval between the position of single peak and f_1/2. We use this method to measure continuous frequencies in a band from −200 MHz to 200 MHz of the MW field. The experimental results and theoretical analysis are presented to describe the effectiveness of this method. For 50 MHz < Δ_MW < 200 MHz, this method solves the problem that the AT splitting cannot be measured by using the standard EIT-AT techniques or multiple atomic-level Rydberg atom schemes.