Correlated single-electron tunneling via mesoscopic metal particles: Effects of the energy quantization

The existing theory of correlated single-electron tunneling in the double normalmetal tunnel junction is extended to the case of an ultrasmall central electrode of the structure. It is shown that the form of the I-V curve of such a system depends on the energy relaxation rate in this electrode. For realistic values of the relaxation rate, the large-scale shape of the dc I-V curve, which is associated with Coulomb correlations, is close to that following from the earlier theory. However, the I-V curve should also exhibit small-scale singularities reflecting the structure of the energy spectrum of the central electrode.