Rydberg spectroscopy of a Rb MOT in the presence of applied or ion created electric fields

Rydberg spectroscopy of rubidium cold atoms trapped in a magneto-optical trap (MOT) was performed in a quartz cell. When electric fields acting on the atoms generated by a plate external to the cell were continuously applied, electric charges on the cell walls were created, as monitored on the Rydberg spectra. Avoiding accumulation of the charges and realizing good control over the applied electric field was instead obtained when the fields were applied only for a short time, typically a few microseconds. In a two-photon excitation via the 62P state to the Rydberg state, the laser resonant with the 52S-62P transition photoionizes the excited state. The photoionization-created ions produce an internal electric field which deforms the excitation spectra, as monitored on the Autler-Townes absorption spectra.