Importance of individual scattering matrix elements at Fano resonances

Abstract

Single particle resonances in quantum wires are generally Fano resonances. In the case ofFano resonances, the scattering phase shift in some channels shows sharp phase drops andthat in the other channels does not. The phase shift in a particular channel can bemeasured and can yield information about the integrated charge localized around thescatterer. This paper tries to analyse whether some channels are more informative thanothers, so that an experimentalist can measure the phase shift in only those channels.The paper also shows how to deal with non-trivial interpretation of density ofstates ‘in the absence of scattering’ in the case of scattering by topological defects.