Tunable Fano effect in parallel-coupled double quantum dot system

TL;DR

This paper theoretically investigates how to control the Fano interference effect in a double quantum dot system using various external parameters, revealing potential applications in quantum computing.

Contribution

It introduces a method to manipulate Fano lineshapes in double quantum dots through external tuning of couplings and magnetic flux, enabling control over quantum states.

Findings

Fano lineshape can be flipped by external fields.

Magnetic flux can exchange the roles of molecular states.

Conductance spectra can be magnetically manipulated without losing lineshape integrity.

Abstract

With the help of the Green function technique and the equation of motion approach, the electronic transport through a parallel-coupled double quantum dot(DQD) is theoretically studied. Owing to the inter-dot coupling, the bonding and antibonding states of the artificial quantum-dot-molecule may constitute an appropriate basis set. Based on this picture, the Fano interference in the conductance spectra of the DQD system is readily explained. The possibility of manipulating the Fano lineshape in the tunnelling spectra of the DQD system is explored by tuning the dot-lead coupling, the inter-dot coupling, the magnetic flux threading the ring connecting dots and leads, and the flux difference between two sub-rings. It has been found that by making use of various tuning, the direction of the asymmetric tail of Fano lineshape may be flipped by external fields, and the continuous conductance spectra may be magnetically manipulated with lineshape retained. More importantly, by adjusting the magnetic flux, the function of two molecular states can be exchanged, giving rise to a swap effect, which might play a role as a qubit in the quantum computation.