Abstract: Quantum coherent transport through a superconductor-quantum-dot coupled system is investigated mainly for considering the current characteristics under the interactions of microwave field and Zeeman field. The mean field BCS theory and non-equilibrium Green function technique are employed to solve the tunneling problem. The Bogoliubov transformation is employed to derive the current formula, and the current-voltage, current-magnetic field and Josephson current curves are given by numerical calculations.

Key words: coupled superconductor system, quantum coherent transport, current characteristics