Nonlinearity of microwave electric field coupled rydberg electromagnetically induced transparency and autler-townes splitting

Abstract

An electromagnetically induced transparency (EIT) of a cascade-three-level atom involving Rydberg level in a room-temperature cell, formed with a cesium 6S1/2-6P3/2-66S1/2 scheme, is employed to detect the Autler-Townes (AT) splitting resulted with a 15.21-GHz microwave field coupling the 66S1/2→65P1/2 transition. Microwave field induced AT splitting, fAT, is characterized by the distance of peak-to-peak of an EIT-AT spectrum. The fAT dependence on the microwave Rabi frequency, WMW, demonstrates two regions, the strong-coupling linear region, fAT ≈ ΩMW and the weak-coupling nonlinear region, fAT.≲ ΩMW. The fAT dependencies on the probe and coupling Rabi frequency are also investigated. Using small probe- and coupling-laser, the Rabi frequency is found to enlarge the linear regime and decrease the uncertainty of the microwave field measurements. The measurements agree with the calculations based on a four-level atomic model.