Steps and dips in the ac conductance and noise of mesoscopic structures

TL;DR

This paper investigates the frequency-dependent ac conductance and noise in mesoscopic structures, revealing steps linked to resonances and dips caused by interference effects, enabling direct measurement of Friedel phases.

Contribution

It demonstrates how steps and dips in ac conductance spectra relate to resonances and interference, providing a new method to measure Friedel phases directly.

Findings

Steps in conductance correspond to resonances and Friedel phases.

Dips are caused by destructive interference similar to Fano effect.

The method allows direct measurement of resonance-related phases.

Abstract

The frequency dependence of the equilibrium ac conductance (or the noise power spectrum) through a mesoscopic structure is shown to exhibit steps and dips. The steps, at energies related to the resonances of the structure, are closely related to the partial Friedel phases of these resonances, thus allowing a direct measurement of these phases (without interferometry). The dips in the spectrum are related to a destructive interference in the absorption of energy by transitions between these resonances, in some similarity with the Fano effect.