Herbert Schoeller

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We study the Fano-Kondo effect in a closed Aharonov-Bohm (AB) interferometer which contains a single-level quantum dot and predict a frequency doubling of the AB oscillations as a signature of Kondo-correlated states. Using the Keldysh formalism, the Friedel sum rule, and the numerical renormalization group, we calculate the exact zero-temperature linear(More)
We discuss electronic transport through a lateral quantum dot close to the singlet-triplet degeneracy in the case of a single conduction channel per lead. By applying the numerical renormalization group, we obtain rigorous results for the linear conductance and the density of states. A new quantum phase transition of the Kosterlitz-Thouless-type is found,(More)
– We present a simple model of electrical transport through a metal–molecule– metal nanojunction that includes charging effects as well as aspects of the electronic structure of the molecule. The interplay of a large charging energy and an asymmetry of the metal– molecule coupling can lead to various effects in non–linear electrical transport. In(More)
Coulomb blockade phenomena and quantum fluctuations are studied in meso-scopic metallic tunnel junctions with high charging energies. If the resistance of the barriers is large compared to the quantum resistance, transport can be described by sequential tunneling. Here we study the influence of quantum fluctuations. They are important when the resistance is(More)
PACS. 73.63-b – Electronic transport in mesoscopic or nanoscale materials and structures. Abstract. – We describe single electron tunneling through molecular structures under the influence of nano-mechanical excitations. We develop a full quantum mechanical model, which includes charging effects and dissipation, and apply it to the vibrating C60 single(More)
Motivated by recent experiments we analyse a new setup of capacitively coupled semiconductor quantum dots. We identify a region where Kondo-assisted tunneling should be observable. We nd an eeective mapping to a single quantum dot with controllable multi-level structure. We study electron transport through strongly coupled quantum dots in the presence of(More)
We study transport through one or two ultrasmall quantum dots with discrete energy levels to which a time-dependent field is applied (e.g., microwaves). The AC field causes photon-assisted tunneling and also transitions between discrete energy levels of the dot. We treat the problem by introducing a generalization of the rotating-wave approximation to(More)
We study electron transport through a small metallic island in the per-turbative regime. Using a diagrammatic real-time technique, we calculate the occupation of the island as well as the conductance through the transistor at arbitrary temperature and bias voltage in forth order in the tunneling matrix elements, a process referred to as cotunneling. Our(More)