Effect of electron correlation on current and current noise for the single- and the two-impurity Anderson model

To study the effects of scattering due to the Coulomb interaction, the dc current and current noise in nonlinear response are investigated on the basis of the second-order perturbation theory for nonequilibrium, using the single- and the two-impurity Anderson model connected to leads. As the numerical result, the shot noise arising from the autocorrelation of the current is suppressed. Additionally, the shot noise occurs in the single-impurity system also from the correlation between the currents with antiparallel spin. From the perturbation theory for nonequilibrium, it is predicted that current noise is caused also from the correlation between the currents with antiparallel spin owing to the interaction though this kind of current noise is not generated in normal noninteracting system.