Fano resonances and decoherence in transport through quantum dots

TL;DR

This paper investigates how Fano resonances in quantum dot transport are affected by decoherence and dissipation, using a tunable microwave device to control and analyze resonance line shapes and their parameters.

Contribution

It introduces a controllable microwave scattering setup to study Fano resonances and demonstrates the equivalence of dephasing and dissipation effects on resonance profiles.

Findings

Dissipation modifies Fano profiles through cavity wall absorption.

Imaginary part of Fano q-parameter measures cavity absorption.

Dephasing and dissipation have equivalent effects on resonance lineshapes.

Abstract

A tunable microwave scattering device is presented which allows the controlled variation of Fano line shape parameters in transmission through quantum billiards. We observe a non-monotonic evolution of resonance parameters that is explained in terms of interacting resonances. The dissipation of radiation in the cavity walls leads to decoherence and thus to a modification of the Fano profile. We show that the imaginary part of the complex Fano q-parameter allows to determine the absorption constant of the cavity. Our theoretical results demonstrate further that the two decohering mechanisms, dephasing and dissipation, are equivalent in terms of their effect on the evolution of Fano resonance lineshapes.