Mathematical Models for Transport in Macroscopic and Mesoscopic Systems - Abstract

Racec, Roxana

Fano resonances in transport through open two-dimensional quantum systems

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. This is a joint work with U. Wulf and P. N. Racec.