Thermoelectric effects in triple quantum dots coupled to a normal and a superconducting leads

Abstract

The thermoelectric transport properties through laterally coupled triple quantum dots attached to a metal and a superconducting electrodes are investigated theoretically in the linear response regime. We calculate thermoelectric quantities by means of non-equilibrium Green's function, analyze their dependence on the energy gap, interdot coupling and Coulomb interaction, and discuss the effects of quantum interference, Coulomb blockade, Andreev reflection and bipolar effect on these quantities in transport process. Our results show that at low temperature the superconducting electrode suppresses the thermal conductance and enhances the thermopower outside the gap, which favors the improvement of figure of merit. In particular, the enhancement function of tunneling coupling between quantum dots and Coulomb blockade on figure of merit, compared with the system with two normal metal electrodes, is greatly increased due to the existence of the gap.