Quantum dot spin effect on the conductance of a quantum wire -: art. no. 233310

A numerically exact calculation of the T=0 transport properties of a quantum wire interacting with a lateral two-level quantum dot is presented. The wire conductance is calculated for all different states of charge and spin of the quantum dot. For a dot with two electrons we obtain an enhancement of the Kondo temperature at the singlet-triplet transition and a nonuniversal scaling law for its dependence upon the dot energy spacing. We find that the Kondo correlation is stronger for a dot spin S(D)similar to1 than for S(D)similar to1/2. In both cases the wire current is totally quenched by the Kondo effect. When the dot is in the mixed-valence regime and 1/2less than or similar toS(D)less than or similar to1 the wire conductance is partially quenched except in a very small region of gate potential where it reaches the maximum value e(2)/h.