Electronic transport through a parallel--coupled triple quantum dot molecule: Fano resonances and bound states in the continuum

TL;DR

This paper analyzes how magnetic flux influences electronic transport, Fano resonances, and bound states in a triple quantum dot molecule, revealing conditions for BIC formation and resonance robustness.

Contribution

It provides analytical expressions for conductance and density of states, demonstrating control of quantum interference effects by magnetic flux in a triple quantum dot system.

Findings

Conductance shows Breit-Wigner and Fano resonances controlled by magnetic flux.

Every two flux quanta, bonding and antibonding states invert roles.

Bound states in the continuum form under specific flux and coupling conditions, with narrow, robust resonances.

Abstract

The electronic transport through a triple quantum dot molecule attached in parallel to leads in presence of a magnetic flux is studied. Analytical expressions of the linear conductance and density of states for the molecule in equilibrium at zero temperature are obtained. As a consequence of quantum interference, the conductance exhibits in general a Breit--Wigner and two Fano resonances, the positions and widths of which are controlled by the magnetic field. Every two flux quanta, there is an inversion of roles of the bonding and antibonding states. For particular values of the magnetic flux and dot-lead couplings, one or even both Fano resonances collapse and bound states in the continuum (BIC's) are formed. The line broadenings of the molecular states are examined as a function of the Aharonov--Bohm phase around the condition for the formation of BIC's, finding resonances extremely narrow and robust against variations of the magnetic field.