Henning Soller Bücher

Focusing on the calculation of full counting statistics (FCS) in superconducting quantum point contacts, this thesis explores their significance in modern microelectronics. Employing a generalized Keldysh formalism, it analyzes FCS for both normal metal-superconductor and superconductor-superconductor contacts, comparing findings with experimental and theoretical data. Key insights include the explanation of doubled shot noise from Andreev reflections and the behavior of Josephson current over extended measurement periods, enhancing the understanding of transport in systems with superconducting leads.

The subject of this thesis is the study of hybrid nanoelectronic components involving superconductors or excitonic systems. The behavior of such electronic devices is relevant both for the miniaturization of electronics as well as for possible future on-chip quantum computation. In order to characterise them the cumulant generating function of charge transfer is calculated. First, quantum point contacts between (conventional und unconventional) superconductors, ferromagnets and semiconductors are investigated. The focus of interest are transport processes involving non-trivial correlated electronic states such as Cooper pairs, excitons or Majorana fermions. In the second part quantum impurities are included and the effects of onsite Coulomb and electron-phonon interaction are discussed. Using these results the possibility to witness entanglement in superconducting beamsplitters is demonstrated. The results are compared both to different theoretical approaches and experimental data.