An ion microscope to probe quantum gases on the single-atom level

This thesis reports on a high-resolution ion microscope specifically designed and built for the probing of ultracold atomic gases. The electrostatic ion-optical system projects individual particles out of the studied gases onto a spatially and temporally resolving detector. This concept permits the imaging of ground-state ensembles, strongly interacting Rydberg systems and cold ionic impurities and thus allows for the investigation of a vast range of few- and many-body quantum phenomena. The particle-based imaging approach offers an excellent spatial and temporal resolution as well as an enormous depth of field and enables three-dimensional imaging via the time-of-flight information of the particles.

The thesis describes the ion microscope and its design in detail and presents the results of an experimental and simulation-based characterization of the imaging performance. It is shown that the instrument offers a lateral spatial resolution on the order of 200 nanometers or even better and that the pulsed operation of the microscope allows for the probing of fast dynamical processes. For ionic systems, the temporal resolution of the particle detection is demonstrated to be on the order of a few nanoseconds. The presented experimental results illustrate the three-dimensional imaging capability of the microscope and its suitability for studies in large-volume bulk gases.

Furthermore, the thesis discusses the observation of individual ion-atom scattering events in a cold atomic ensemble. While the experimental results of this collision study are well described by a classical model, they illustrate the large potential offered by the ion microscope for future collision and transport studies at lower energies and even in the quantum regime.