Electromagnetically induced transparency in an interacting Rydberg gas

We perform spectroscopic measurements of electromagnetically induced transparency (EIT) in a cold Rydberg gas. I will discuss three of our recent results: 1) the lensing effect – a Gaussian coupling beam tightly focused on a laser-cooled atomic cloud produces an inhomogeneity in the coupling Rabi frequency along the transverse direction and makes the EIT area acting like a gradient-index medium; 2) spectral shift and dephasing of EIT spectra in a strongly interacting Rydberg gas from the single-atom EIT resonance. We characterize and simulate the shift and dephasing as a function of atomic density, probe Rabi frequency, and principal quantum number of Rydberg states; 3) Lévy statistics of the laser excitation of cold and randomly distributed atoms to Rydberg states. We develop a statistical approach for the modelling of probe light transmission through a cold atom gas driven under conditions of electromagnetically induced transparency involving a Rydberg state. The simulated results are in good agreement with a Monte Carlo rate equations simulation and with experimental data.