Single electron circuits with ballistic hot electrons

In contrast to photonic quantum optics, electron quantum optics is based on utilizing the quantum states of fermions instead of bosons, whose different particle statistics can be visualized in equivalent setups. The development of clocked electron sources and their combination with charge detectors enable performing and observing such experiments on the scale of individually isolated electron wave packets. The non-adiabatic single-electron pump, also applied in metrology, represents an example of these electron sources and provides single hot (i.e. high-energy) electrons on demand. In this work, the foundations are laid for combining a single-electron pump with electron quantum optics experiments at excess energies far from thermal equilibrium, where single ballistic (i.e. propagating almost interaction-free) electrons will be detected individually by means of a charge detector. For this purpose, the electronic transport at excess energies of many millielectronvolts is investigated as a function of various influencing parameters on the basis of a large number of different wafers and geometries. In addition to material properties such as impurities, electron-electron and electron-LOphonon interactions are observed here as interaction mechanisms relevant for the scattering of hot electrons, each playing a dominant role in different energetic regimes. In particular, interactions with longitudinal optical phonons are investigated in detail and good agreement to the descriptive model of an electron in a transverse parabolic confinement potential is found. Altogether, for the minimization of scattering that is crucial in an interference-based experiment, an intermediate regime is identified as the optimal regime of hot-electron excess energies. A single-shot mode to operate and evaluate clocked single-electron circuits is presented, which based on a reconstruction of the detector characteristic extracts the full counting statistics of a transport experiment. Subsequently, this operating mode is transferred into a circuit with injection of hot ballistic electrons. Their successful detection means that an electron, which in a first step propagates through a single-electron circuit almost free of interactions, can in a second step be captured for detection by a charge detector in a controlled and reproducible manner. Finally, by integrating two of these detector elements into a single circuit, evaluation of coincidence correlations is demonstrated in a circuit where multiple electrons are injected.