Off-resonant transport through an ultra-small quantum dot

Employing the Anderson impurity model, we have investigated tunneling properties through an ideal quantum dot near the conductance minima. Current contributions from various types of tunneling processes are obtained based on the Landauer-type formula with the Golden rule. We show that the inelastic cotunneling is suppressed in the quantum confinement limit, and thus the off-resonant transport is given by the elastic cotunneling at low temperature (k(B)T much less than Gamma, Gamma: dot-reservoir coupling constant), or by the sequential tunneling of thermally activated electrons at high temperature (k(B)T much greater than Gamma).