Josephson current transport through T-shaped double quantum dots

Abstract

The Josephson current through T-shaped double quantum dots (TDQD) has beeninvestigated theoretically using the non-equilibrium Green’s function method.Hybridization of energy levels of the central quantum dot (QD) and side QDresults in the renormalization of Andreev bound states, which dominates theJosephson current. Consequently, Josephson critical current can be modulated tointerference construction and destruction by adjusting the energy levels of two QDsε1,ε2, and interdotcoupling tc. Indetail, when ε1ε2 = tc2 is fulfilled, interference construction occurs and whenε2 = 0, interference destruction happens. These results are similar to the interferencebehavior of linear conductance in normal TDQD devices. In addition,Josephson critical current also shows Fano characteristics with variation ofε2 and the resonance line shape is determined byε1. Finally, the Josephson current has a symmetric relation ofI(ε1,ε2) = I(−ε1,−ε2) due to electron–hole symmetry.