Probing decoherence through Fano resonances

TL;DR

This paper explores how decoherence affects Fano resonances in wave transmission, revealing that the Fano asymmetry parameter traces distinct complex-plane trajectories depending on the decoherence type, with experimental validation.

Contribution

It introduces a method to analyze decoherence effects on Fano resonances via complex-plane trajectories of the asymmetry parameter, distinguishing dissipation from dephasing, supported by microwave and quantum dot experiments.

Findings

Decoherence causes characteristic trajectories in the complex plane of the Fano parameter.

Different types of decoherence (dissipation vs. dephasing) produce distinct trajectories.

Experimental data confirms the theoretical predictions.

Abstract

We investigate the effect of decoherence on Fano resonances in wave transmission through resonant scattering structures. We show that the Fano asymmetry parameter q follows, as a function of the strength of decoherence, trajectories in the complex plane that reveal detailed information on the underlying decoherence process. Dissipation and unitary dephasing give rise to manifestly different trajectories. Our predictions are successfully tested against microwave experiments using metal cavities with different absorption coefficients and against previously published data on transport through quantum dots. These results open up new possibilities for studying the effect of decoherence in a wide array of physical systems where Fano resonances are present.