Single-electron tunneling in systems of small junctions coupled to an electromagnetic environment

A simple approach is proposed to describe the influence of the electromagnetic environment on the sequential single-electron tunneling in systems of ultrasmall tunnel junctions. As an application we consider a system of two junctions in series coupled to an Ohmic environment. An increase of the enivironment resistance (i) widens the Coulomb-blockade region and (ii) suppresses the peaks that the conductance shows as a function of the gate voltage. The environment is responsible for an unusual temperature dependence of these peaks, which may explain recent experiments with GaAs lateral microstructures.