Kondo effect in a few-electron quantum ring

A small tuneable quantum ring with less than ten electrons was shown to exhibit Aharonov-Bohm oscillations as well as Coulomb blockade. At strong coupling to the leads, evidence of a Kondo effect induced by a single spin on the ring was obtained. Analysis of the phase evolution of the Aharonov-Bohm effect in the Kondo regime yielded phase jumps by π at the Coulomb-blockade resonances and a smooth shift of the Aharonov-Bohm maxima in between.