  Pauli spin blockade (PSB) is a significant physical effect in double quantum
dot (DQD) systems. In this paper, we start from the fundamental quantum model
of the DQD with the electron-electron interaction being considered, and then
systematically study the PSB effect in DQD by using a recently developed
non-perturbative method, the hierarchical equations of motion (HEOM) approach.
The physical picture of the PSB is elucidated explicitly and the gate voltage
manipulation is described minutely, which are both qualitatively consistent
with the experimental measurements. When dotdot exchange interaction is
involved, the PSB effect may be lifted by the strong antiferromagnetic exchange
coupling.
