Control of the supercurrent through a parallel-coupled double quantum dot system

The supercurrent through parallel-coupled double quantum dots connected to two superconductor leads is investigated theoretically. The possibility of controlling the supercurrent of the system is explored by tuning the interdot coupling, dot energy levels, total magnetic flux treading the ring connecting dots and leads, and flux difference between two subrings. Owing to the interdot coupling, one strongly and one weakly coupled states of the system can be formed. The magnetic flux can exchange the function of the two states, which leads to a swap effect. It is found that the oscillation period of the supercurrent with respect to the magnetic flux depends not only on the flux difference but also on the ratio of the two parts fluxes.