Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 29: Transport properties II
HL 29.5: Vortrag
Mittwoch, 29. März 2006, 18:00–18:15, HSZ 01
Fano resonances in transport through open quantum systems — •Roxana Racec1,2 and Ulrich Wulf1,3 — 1Technische Universität Cottbus, Fakultät 1, Postfach 101344, 03013 Cottbus, Germany — 2University of Bucharest, Faculty of Physics, PO Box MG-11, 077125 Bucharest Magurele, Romania — 3IHP/BTU Joint Lab, Postfach 101344, 03013 Cottbus, Germany
We develop a theory for the measured Fano resonances in the conductance of a quantum dot strongly coupled to the leads. A nonseparable potential is considered which assures for the channel mixing. Our central result is that there is a single, well-defined resonant transmission channel even in presence of channel coupling. This resonant channel is associated with a single pole of the S-matrix. In addition, there is a background part of the S-matrix arising from poles other than the resonant one. It can be shown that this constant part of the S-matrix can be split in one part which interferes coherently with the resonant channel (coherent background) and a noncoherent part (noncoherent background). The interplay between the coherent background and the resonant channel determines the single asymmetry parameter seen in the experiment. The noncoherent background part of the S-matrix results in a noncoherent constant contribution to the conductance which is also seen in the experiment.