Kondo physics with single electron transistors

The coupling between the confined droplet of electrons and the leads in a single electron transistor (SET) has made it possible to explore Kondo physics in ways that were never before possible. In particular, whereas the energy of the localized spin is fixed for the traditional Kondo system, a magnetic impurity in a metal, it can be varied in an SET, allowing detailed comparisons with the theory for the equilibrium Kondo problem. Furthermore, one can apply a finite bias voltage between the leads revealing non-equilibrium Kondo effects as well.