Zeeman-split mesoscopic transport through a normal-metal-quantum-dot-superconductor system with ac response - art. no. 094505

We have investigated the Zeeman-split mesoscopic transport through the norm al-metal-quantum-dot-superconductor system applied with a microwave field. We employ BCS theory to describe the Hamiltonian of the superconducting lea d. The time-averaged tunneling current formula is derived by using the Keld ysh's nonequilibrium Green-function technique in the Nambu representation, The Multilevel quantum dot is considered for the noninteraction system in t he calculations. The spin split Andreev reflection and photon-electron pump ing behaviors are investigated in the presence of a Zeeman magnetic field. The resonant structure versus Zeeman energy and gate voltage is revealed. T he Zeeman-split photon-assisted I-V characteristics are evaluated for the s ingle-channel quantum-dot system. By adjusting the Zeeman magnetic field, w e can obtain a large resonant tunneling current even if in the Andreev refl ection regime. The current appears to have interesting structures versus Ze eman energy for the multichannel quantum-dot system associated with a diffe rent gate voltage. The negative and positive current appear in the symmetri c forms by controlling the Zeeman field.