Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 8: Posters Transport

TT 8.48: Poster

Freitag, 4. März 2005, 14:00–18:00, Poster TU C

Noise in a non-adiabatic electron pump — •Michael Straß, Sigmund Kohler, and Peter Hänggi — Institut für Physik, Universität Augsburg

We investigate the electron transport in a two-terminal device consisting of two sites driven by an external AC field. The current and the associated noise are computed numerically within a Floquet approach which is also valid for non-adiabatic driving [1]. As a result, we find maxima of the pump current at the multi-photon resonances even if no voltage is applied. The transport in this setup can be optimized tuning the ratio of the intrasite coupling and the coupling of the sites to the leads. As a measure of the relative noise strength and therefore the transport properties, we study the Fano factor as a function of driving frequency and amplitude. At the multi-photon resonances, the Fano factor shows distinct minima.

The numerically exact solution is in addition compared to analytical results obtained within a high-frequency approximation [2]. This also provides a physical understanding of the current and noise suppressions observed for specific driving parameters. Possible experimental realizations of the system at hand are molecular wires in laser fields, quantum double-wells in heterostructures driven by electrical fields, and coupled quantum dots exposed to microwave radiation.

[1] S. Camalet, S. Kohler, and P. Hänggi, Phys. Rev. B 70, 155326 (2004)

[2] S. Kohler, S. Camalet, M. Strass, J. Lehmann, G.-L. Ingold, and P. Hänggi, Chem. Phys. 296, 243 (2004).