Observation of the Fano-Kondo Anti-Resonance in a Quantum Wire with a Side-Coupled Quantum Dot

TL;DR

This study reports the experimental observation of Fano-Kondo anti-resonance in a quantum wire with a side-coupled quantum dot, revealing how conductance dips evolve with coupling strength and temperature, confirming theoretical predictions.

Contribution

First experimental observation of Fano-Kondo anti-resonance in a quantum wire with a side-coupled quantum dot, demonstrating conductance behavior and phase shift consistent with theory.

Findings

Fano effect causes conductance dips in weak coupling regime.

Conductance decreases between dips as coupling increases.

Phase shift remains locked at π/2 near the unitary limit.

Abstract

We have observed the Fano-Kondo anti-resonance in a quantum wire with a side-coupled quantum dot. In a weak coupling regime, dips due to the Fano effect appeared. As the coupling strength increased, conductance in the regions between the dips decreased alternately. From the temperature dependence and the response to the magnetic field, we conclude that the conductance reduction is due to the Fano-Kondo anti-resonance. At a Kondo valley with the Fano parameter $q\approx 0$, the phase shift is locked to $\pi/2$ against the gate voltage when the system is close to the unitary limit in agreement with theoretical predictions by Gerland {\it et al.} [Phys. Rev. Lett. {\bf 84}, 3710 (2000)].