STRONG ELECTRON-TUNNELING IN MESOSCOPIC METALLIC GRAINS

Electron tunneling through mesoscopic metallic grains can be treated p erturbatively only provided the tunnel junction conductances are suffi ciently small. If it is not the case, fluctuations of the grain charge become strong. As a result (i) contributions of all - including high energy - charge states become important and (ii) excited charge states become broadened and essentially overlap. At the same time the grain charge remains discrete and the system conductance e-periodically depe nds on the gate charge. We develop a nonperturbative approach which ac counts for all these features and calculate the temperature dependent conductance of the system in the strong tunneling regime at different values of the gate charge.