Towards two-channel Kondo effect in triple quantum dot

The effective spin Hamiltonian of a triple quantum dot with odd electron occupation weakly connected in series with left (l) and right (r) metal leads is composed of two-channel exchange and co-tunneling terms. Renormalization group equations for the corresponding three exchange constants J_l, J_r and J_lr are solved (to third order). Since J _lr is relevant, the system is mapped on an anisotropic two-channel Kondo problem. The structure of the conductance as a function of temperature and gate voltage implies that in the weak- and intermediate-coupling regimes, two-channel Kondo physics persists at temperatures as low as several T _K. At even electron occupation, the number of channels equals twice the spin of the triple dot (hence it is a fully screened impurity).