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).