High resolution Rydberg spectroscopy of ultracold rubidium atoms

We present experiments on two-photon excitation of Rb-87 atoms to Rydberg states. For this purpose, two continuous-wave (cw)-laser systems for both 780 nm and 480 nm have been set up. These systems are optimized to, a small linewidth (well below 1 MHz) to get both an efficient excitation process and good spectroscopic resolution. To test the performance of our laser system, we investigated the Stark splitting of Rydberg states. We were able to see for both of the n = 41D finestructure states the electrical field dependent broken vertical bar m(j)broken vertical bar splitting. To show the ability of spatially selective excitation to Rydberg states, we excited rubidium atoms in an electrical field gradient and investigated both linewidths and lineshifts. Furthermore we were able to excite the atoms selectively from the two hyperfine ground states to Rydberg states. Finally, we investigated the Autler-Townes splitting of the 5S(1/2)(F = 2)-> 5P(3/2)(F = 3) transition coupled to the light field via a Rydberg state to determine the Rabi frequency of this excitation step.