We report on the realization of high resolution electron microscopy of Rydberg-excited ultracold atomic samples. The implementation of an ultraviolet laser system allows us to excite the atom, with a single-photon transition, to Rydberg states. By us
ing the electron microscopy technique during the Rydberg excitation of the atoms, we observe a giant enhancement in the production of ions. This is due to $l$-changing collisions, which broaden the Rydberg level and therefore increase the excitation rate of Rydberg atoms. Our results pave the way for the high resolution spatial detection of Rydberg atoms in an atomic sample.
We characterize the two-photon excitation of an ultracold gas of Rubidium atoms to Rydberg states analysing the induced atomic losses from an optical dipole trap. Extending the duration of the Rydberg excitation to several ms, the ground state atoms
are continuously coupled to the formed positively charged plasma. In this regime we measure the $n$-dependence of the blockade effect and we characterise the interaction of the excited states and the ground state with the plasma. We also investigate the influence of the quasi-electrostatic trapping potential on the system, confirming the validity of the ponderomotive model for states with $20leq nleq 120$.
