Investigation of fluorescence versus transmission readout for three-photon Rydberg excitation used in electrometry

We present a three-photon based fluorescence readout method where the strength of the fluorescence scales with the strength of the radio-frequency field being applied. We compare this method to conventional three-photon electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA). Our demonstrated three-photon EIA/EIT sensitivity in the collinear three-photon Cesium system is the best reported to date at roughly 30 (same units). The fluorescence is nearly fourfold better in sensitivity compared to EIA/EIT readout.