Fano Resonance in a Quantum Wire with a Side-coupled Quantum Dot

TL;DR

This paper presents an experimental study of Fano resonance in a quantum wire with a side-coupled quantum dot, demonstrating its coherence, temperature dependence, and potential as an interferometer for phase measurement.

Contribution

It provides the first detailed transport experiment on Fano effect in this geometry, highlighting its advantages for studying quantum coherence and phase evolution.

Findings

Fano resonance observed between quantum dot and T-shaped junction.

Resonance is purely coherent, with temperature-dependent broadening.

Geometry can serve as an interferometer to measure electron phase.

Abstract

We report a transport experiment on the Fano effect in a quantum connecting wire (QW) with a side-coupled quantum dot (QD). The Fano resonance occurs between the QD and the "T-shaped" junction in the wire, and the transport detects anti-resonance or forward scattered part of the wavefunction. While in this geometry it is more difficult to tune the shape of the resonance than in the previously reported Aharonov-Bohm-ring type interferometer, the resonance purely consists of the coherent part of transport. By utilizing this advantage, we have qualitatively explained the temperature dependence of the Fano effect by including the thermal broadening and the decoherence. We have also proven that this geometry can be a useful interferometer to measure the phase evolution of electrons at a QD.