Josephson current transport through T-shaped double quantum dots

The Josephson current through T-shaped double quantum dots (TDQD) has been investigated theoretically using the non-equilibrium Green's function method. Hybridization of energy levels of the central quantum dot (QD) and side QD results in the renormalization of Andreev bound states, which dominates the Josephson current. Consequently, Josephson critical current can be modulated to interference construction and destruction by adjusting the energy levels of two QDs epsilon(1), epsilon(2), and interdot coupling t(c). In detail, when epsilon(1)epsilon(2) = t(c)(2) is fulfilled, interference construction occurs and when epsilon(2) = 0, interference destruction happens. These results are similar to the interference behavior of linear conductance in normal TDQD devices. In addition, Josephson critical current also shows Fano characteristics with variation of epsilon(2) and the resonance line shape is determined by epsilon(1). Finally, the Josephson current has a symmetric relation of I(epsilon(1), epsilon(2)) = I (-epsilon(1), -epsilon(2)) due to electron-hole symmetry.