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Regensburg 2007 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 18: Nanoelectronics I - Quantum Dots, Wires, Point Contacts

TT 18.2: Talk

Wednesday, March 28, 2007, 14:15–14:30, H19

Co-tunneling effects in transport through interacting quantum dots — •Jasmin Aghassi1,2, Matthias Hettler1, and Gerd Schön1,21Forschungszentrum Karlsruhe, INT, Postfach 3640, 76201 Karlsruhe — 2Institut für theoretische Festkörperphysik, Universität Karlsruhe, 76128 Karlsruhe

We study charge transport in quantum dot systems within a diagrammatic technique. The current-voltage characteristics as well as the current noise are calculated within second-order perturbation expansion in the coupling parameter Γ. We allow for an intermediate coupling regime up to coupling constants of Γ=kB T, where kB is the Boltzmann constant and T the temperature. We explicitly account for intra- and inter-dot Coulomb interactions and the resulting many-body states of the quantum dots. For a single multilevel quantum dot we investigate the co-tunneling effects on the conductance and noise of the system in dependence of an applied gate voltage. In the Coulomb blockade region super-Poissonian noise is observed at the inelastic co-tunneling energy scale. This energy scale is also observable in the conductance in some cases. For non-local systems such as chains of coupled quantum dots (“artificial molecules”) sequential tunneling results for transport under asymmetric conditions, i.e. non-resonant dots or asymmetric couplings are compared to second order results.
A. Thielmann et.al., Phys. Rev. Lett., 95, 146806 (2005)
J. Aghassi et.al, Appl. Phys. Lett. 89, 052101 (2006), Phys. Rev.B 73, 195323 (2006)

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