Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

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

TT 18.7: Vortrag

Mittwoch, 28. März 2007, 15:30–15:45, H19

Adiabatic Pumping through Metallic Single-Electron Devices — •Nina Winkler, Michele Governale, and Jürgen König — Institut für Theoretische Physik III · Ruhr-Universität Bochum

In a mesoscopic system a DC current can be generated even at zero bias voltage by periodically changing some of its properties in time. This transport mechanism is called pumping. If the time dependence of the parameters is slow compared to the internal time scales of the system, pumping is adiabatic.

In analogy to Ref. [ 1], we develop a diagrammatic real-time approach to adiabatic pumping through a system of tunnel-coupled metallic islands, performing a systematic perturbative expansion in powers of the tunnel-coupling strengths. This method allows us to identify the different physical processes which contribute to the pumped charge.

We first apply our formalism to a single-electron transistor consisting of one metallic island with Coulomb interaction tunnel coupled to two non-interacting leads. We compute the pumped charge up to first order in the tunnel-coupling strength, finding that the contribution in first order is due to the renormalisation of the charging-energy gap. For the case of pumping with the two tunnel-coupling strengths, this term becomes the dominant one. Furthermore, we consider pumping with the charging-energy gaps in a system consisting of two tunnel-coupled metallic islands. We calculate the pumped charge through this system, and investigate the issue of pumped-charge quantisation.

[ 1] J. Splettstoesser, M. Governale, J. König, and R. Fazio, Phys. Rev. B 74, 085305 (2006).