Polarization Dependent Dark Resonances in Electromagnetically Induced Transparency with Rydberg Atoms

We present an experimental study of optical pumping into different hyperfine Rydberg states in a Rb cell using a 4 level EIT scheme. The lower three levels are coupled together using lasers, while microwaves couple the two upper Rydberg states together. With different laser and microwave polarizations, different hyperfine states will be coupled together resulting in polarization dependent dark resonances. The experimental results match our theoretical calculations using the complete 4 level system. This technique can also be used for quantum assisted sensing of the amplitude and polarization of the electric field that is coupling the Rydberg states together.