Fano-Andreev effect in a parallel double quantum dot structure

We investigate the Andreev reflection in a parallel double quantum dot structure, by considering one metallic lead coupled to one $s$-wave superconductor through the quantum dots. It is found that if an arm of this system provides the reference channel for the Andreev reflection, the Fano line shapes will have opportunities to appear in the linear conductance spectra and can be reversed by adjusting the dot level or local magnetic flux. To present the underlying physics, we obtain the Fano form of the linear conductance expression. Despite the complicated structural parameters, the property of the Fano effect is clearly shown. We believe that the results of this work will help us to understand the Fano interference in the Andreev reflection process.