Fano effect in a ring-dot system with tunable coupling

TL;DR

This paper investigates Fano resonances in a quantum ring-dot system, demonstrating how coupling strength and magnetic flux influence resonance symmetry, with temperature-dependent effects and theoretical modeling confirming experimental results.

Contribution

It presents experimental observation of Fano effects in a tunably coupled ring-dot system and models the phenomena including decoherence effects.

Findings

Fano resonances depend on magnetic flux and coupling strength.

Fano effect disappears above 0.65 K, while Aharonov-Bohm oscillations persist up to 4.2 K.

Theoretical model agrees well with experimental data.

Abstract

Transport measurements are presented on a quantum ring that is tunnel-coupled to a quantum dot. When the dot is in the Coulomb blockade regime, but strongly coupled to the open ring, Fano line shapes are observed in the current through the ring, when the electron number in the dot changes by one. The symmetry of the Fano resonances is found to depend on the magnetic flux penetrating the area of the ring and on the strength of the ring-dot coupling. At temperatures above T=0.65 K the Fano effect disappears while the Aharonov-Bohm interference in the ring persists up to T=4.2 K. Good agreement is found between these experimental observations and a single channel scattering matrix model including decoherence in the dot.