Using the equivalent single-particle multi-channel network and the Landauer formula, we theoretically study anti-resonances in conductance of a normal metal–superconductor junction with a side-coupled quantum dot. The transport properties depend on the interplay between the Coulomb blockade effect and the Andreev reflection. It is found that the calculated dependence of the conductance on the gate voltage of dot exhibits two anti-resonant conductance dips. This behavior is caused by the destructive interference of the wave directly transmitted through the normal metal–superconductor junction and the wave reflected from the dot. Moreover, we find that the shape of two anti-resonance profile is symmetric, due to the Andreev reflection, depending on the strength of coupling between the quantum dot and normal metal.
Environmental Coulomb blockade of topological superconductor-normal metal junctions