Electron transport through a strongly interacting quantum dot coupled to a normal metal and BCS superconductor

Abstract

We study electron transport through a quantum dot coupled to a normal metal and BCS-like superconductor (N–QD–S) in the presence of the Kondo effect and Andreev scattering. The system is described by the single impurity Anderson model in the limit of strong on-dot interaction. To study electron transport, we use the recently proposed equation of motion technique for the Keldysh non-equilibrium Green's function together with the modified slave boson approach. We derive the formula for the current which contains various tunnelling processes and we apply it to a study of the transport through the system. We find that the Andreev conductance is strongly suppressed and there is no zero-bias (Kondo) anomaly in the differential conductance. We discuss the effects of the particle–hole asymmetry in the electrodes as well as the asymmetry in the couplings.