Research group Stibor
The coherent control of charged particles such as electrons and ions in free space is currently gaining relevance in fundamental research as well as for technical applications. Interesting questions arise in connection with decoherence, being the loss of quantum nature in a system due to the interaction with the environment. The decoherence through Coulomb-interaction is a fascinating field in experimental quantum physics with important applications in quantum logic, surface analysis, microscopy and the realization of hybrid quantum systems.
In this context, one project in our research group studies the decoherence of an electronic and macroscopic superposition state near semiconducting, metallic or superconducting surfaces. The quantum-classical transition region is analyzed experimentally in a biprism electron interferometer that is based on the setup of Sonnentag et al. . Thereby our experiments focus on the interaction between coherent electrons and a superconducting environment.
The second project in our research group is the further development of the first ion-interferometer realized by Maier and Hasselbach  and its application for fundamental quantum-optical experiments. The main component in the setup is a novel single-atom tip ion source for intensive, coherent helium and hydrogen ion beams . A biprism beam splitter will create a spatial superposition state of the coherent ions and the ion matter wave will be measured by interference. Thereby dephasing effects are relevant that are due to temperature drifts or mechanical and electromagnetic oscillations. They reduce the contrast of the interference pattern. Our group develops methods for correlation analysis of the spatial and temporal ion data in the detector to decrease the influence of such dephasing.
In our setup, the high technical standard in the generation of electron-beams and their precise control can be applied on ions. With the realization of an ion-interferometer, novel experiments in connection with the magnetic and electric Aharonov-Bohm effect as well as highly sensitive, compact sensors for rotation and acceleration come into the reach of current technical possibilities. The additional parameter of charge provides a crucial advantage to neutral atom- and molecule-interferometers and opens the door for fundamental, quantum-mechanical experiments.
 P. Sonnentag and F. Hasselbach Phys. Rev. Lett. 98, 200402 (2007)
 F. Hasselbach, U. Maier, in: Quantum Coherence and Decoherence: Proc.
ISQM-Tokyo '98, ed. by Y.A. Ono, K. Fujikawa (Elsevier, Amsterdam, 1999), p. 299
 H.S. Kuo, I.S. Hwang, T.Y. Fu et al., Japanese J. Appl. Phys. 45, 8972 (2006)