Simultaneous Use of Cs and Rb Rydberg Atoms for Independent RF Electric   Field Measurements via Electromagnetically Induced Transparency
  We demonstrate simultaneous electromagnetically-induced transparency (EIT) with cesium (Cs) and rubidium (Rb) Rydberg atoms in the same vapor cell with coincident (overlapping) optical fields. Each atomic system can detect radio frequency (RF) electric (E) field strengths through modification of the EIT signal (Autler-Townes (AT) splitting), which leads to a direct SI traceable RF E-field measurement. We show that these two systems can detect the same the RF E-field strength simultaneously, which provides a direct in situ comparison of Rb and Cs RF measurements in Rydberg atoms. In effect, this allows us to perform two independent measurements of the same quantity in the same laboratory, providing two different immediate and independent measurements. This gives two measurements that helps rule out systematic effects and uncertainties in this E-field metrology approach, which are important when establishing an international measurement standard for an E-field strength and is a necessary step for this method to be accepted as a standard calibration technique. We use this approach to measure E-fields at 9.2~GHz, 11.6~GHz, and 13.4~GHz, which correspond to three different atomic states (different principal atomic numbers and angular momentums) for the two atom species. 
Matt T. Simons, Joshua A. Gordon, and Christopher L. Holloway
physics.atom-ph