Electromagnetically induced transparency and population repump readout of Rydberg states of Cs atoms in a J-scheme

Rydberg atom electrometry offers traceable electric field measurements over many decades of radio frequencies in a single device. Miniaturization of these sensors is primarily limited by the requirements of the lasers used. Here, we demonstrate a three-photon sensing scheme using a J-shaped energy level coupling that can be achieved using external cavity diode lasers without the need for a doubling crystal or a tapered amplifier. In the low laser power regime, we demonstrate a full width at half maximum linewidth of 1.3 MHz. We demonstrate that, for radio frequency field electrometry using conventional heterodyne techniques, we can detect a 4.7 GHz at a sensitivity of 27 μV m−1 Hz−1/2, comparable to that of two-photon detection schemes that require the use of a tapered amplifier. We also investigate a modified scheme where the probe laser is locked to a different hyperfine state, thus measuring the two-photon electromagnetically induced transparency in the other two lasers via the change in population of this separate state due to repumping. In this scheme, we find the sensitivity for a 4.7 GHz field to be 39 μV m−1 Hz−1/2 and demonstrate that the amplitude scaling with probe power offers a different saturation profile than the linked J-scheme counterpart.