Spin fractionalization of an even number of electrons in a Quantum dot

An experiment is proposed of non perturbative tunneling in a Quantum dot connected to leads in a pillar configuration, which would shed light on the physics of the mesoscopic Kondo problem. We propose for the first time that what is coupled to the leads in the case of even number of electrons on the dot is not just the electrons on the QD, with their own spins, but the very total spin of the dot macroscopic state itself, that displays features of the Kondo physics, that leads to fractionalization of the spin in the dot, that is to a "spinon box".Comment: 4 pages revtex file, 1 figur