arXiv subjects

Bastian Hiltscher

Publications and source records attributed to Bastian Hiltscher.

4 recordsLinked to original sources

arXiv2012

AC Josephson transport through interacting quantum dots

We investigate the AC Josephson current through a quantum dot with strong Coulomb interaction attached to two superconducting and one normal lead. To this end, we perform a perturbation expansion in the tunneling couplings within a diagrammatic real-time technique. The AC Josephson current is connected to the reduced density matrix elements that describe superconducting correlations induced on the quantum dot via proximity effect. We analyze the dependence of the AC signal on the level position of the quantum dot, the charging energy, and the applied bias voltages.

cond-mat.mes-hall↗

arXiv2011

Adiabatic pumping in a double-dot Cooper-pair beam splitter

We study adiabatic pumping through a double quantum dot coupled to normal and superconducting leads. For this purpose a perturbation expansion in the tunnel coupling between the dots and the normal leads is performed and processes underlying the pumping current are discussed. Features of crossed Andreev reflection are investigated in the average pumped charge and related to local Andreev reflection in a single quantum dot. In order to distinguish Cooper pair splitting from quasi-particle pumping, we compare the properties of Cooper pair pumping with single-electron pumping in a system with only normal leads. The dependence on the average dot level and the coupling asymmetry turn out to be the main distinguishing features. This is contrasted with the linear conductance for which it is more difficult to distinguish single-particle from Cooper pair transport.

cond-mat.mes-hall↗

arXiv2010

Spin-dependent transport through quantum-dot Aharonov-Bohm interferometers

We study the influence of spin polarization on the degree of coherence of electron transport through interacting quantum dots. To this end, we identify transport regimes in which the degree of coherence can be related to the visibility of the Aharonov-Bohm oscillations in the current through a quantum-dot Aharonov-Bohm interferometer with one normal and one ferromagnetic lead. For these regimes, we calculate the visibility and, thus, the degree of coherence, as a function of the degree of spin polarization of the ferromagnetic lead.

cond-mat.mes-hall↗

arXiv2010

Interference and interaction effects in adiabatic pumping through quantum dots

In order to investigate the effects of interference and interaction in adiabatic pumping, we consider an Aharonov-Bohm (AB) interferometer with a quantum dot embedded either in one or in both arms. We employ a real-time formalism and we perform an expansion both in the tunnel-coupling strengths between dot and leads and in the pumping frequency, taking into account the Coulomb interaction non perturbatively. We find that pumping in a single-dot AB interferometer has a peristaltic but phase-coherent character. In a double-dot AB interferometer, we find a pumping mechanism that relies purely on quantum mechanical interference and has no classical counterpart.

cond-mat.mes-hall↗