Tunable Fano effect in parallel-coupled double quantum dot system

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 interdot 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 line shape in the tunneling spectra of the DQD system is explored by tuning the dot-lead coupling, the interdot coupling, the magnetic flux threading the ring connecting dots and leads, and the flux difference between two subrings. It has been found that by making use of various tunings, the direction of the asymmetric tail of Fano line shape may be flipped by external fields and the continuous conductance spectra may be magnetically manipulated with the line shape 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. © 2005 The American Physical Society.