Rydberg electromagnetically induced transparency and Autler-Townes splitting in a weak radio-frequency electric field

We utilize an electromagnetically induced transparency (EIT) of a three-level cascade system involving Rydberg state in a room-temperature cell, formed with a cesium 6S(1/2)-6P(3/2)-66S(1/2) scheme, to investigate the Autler-Townes (AT) splitting resulting from a 15.21-GHz radio-frequency (RF) field that couples the vertical bar 66S(1/2)> -> vertical bar 65P(1/2)> Rydberg transition. The radio-frequency electric field induced AT splitting, gamma AT, is defined as the peak-to-peak distance of an EIT-AT spectrum. The dependence of AT splitting gamma AT on the probe and coupling Rabi frequency, Omega(p )and Omega(c), is investigated. It is found that the EIT-AT splitting strongly depends on the EIT linewidth that is related to the probe and coupling Rabi frequency in a weak RF-field regime. Using a narrow linewidth EIT spectrum would decrease the uncertainty of the RF field measurements. This work provides new experimental evidence for the theoretical framework in [J. Appl. Phys. 121, 233106 (2017)].