Spin-polarized quantum transport through a quantum dot in time-varying magnetic field

Based on the many-body Schrodinger equation, we derive the spin-dependent rate equations for resonant transport through a quantum dot in time-varying magnetic field which leads to the spin flip. From the rate equations which resemble the optical Bloch equation we are able to identify the spin current viewed as the imbalance transport rates between spin up and down. It is shown that the stationary charge current I=I(t->∼) does not depend on the magnetic field in agreement with the result in Phys. Rev. B 53 (1996) 15932, while the spin current oscillates with the rotating magnetic field