Quantum transport through a double Aharonov-Bohm interferometer in the presence of Andreev reflection

Quantum transport through a double Aharonov-Bohm interferometer in the presence of Andreev reflection is investigated in terms of the nonequilibrium Green function method with which the reflection current is obtained. Tunable Andreev reflection probabilities depending on the interdot coupling strength and magnetic flux as well are analysized in detail. It is found that the oscillation period of the reflection probability with respect to the magnetic flux for the double interferometer depends linearly on the ratio of two parts magnetic fluxes n, i.e., 2(n+1)pi, while that of a single interferometer is 2 pi. The coupling strength not only affects the height and the linewidth of Andreev reflection current peaks vs gate voltage but also shifts the peak positions. It is furthermore demonstrated that the Andreev reflection current peaks can be tuned by the magnetic fluxes.