Quantum interference and Coulomb interaction in arrays of tunnel junctions- art. no. 115109

We study the electronic properties of an array of small metallic grains con nected by tunnel junctions. Such an array serves as a model for a granular metal. Previous theoretical studies of junction arrays were based on models of quantum dissipation which did not take into account the diffusive motio n of electrons within the grains. We demonstrate that these models break do wn at sufficiently low temperatures: for a correct description of the scree ning properties of a granular metal at low energies, the diffusive nature o f the electronic motion within the grains is crucial. We present both a dia grammatic and a functional integral approach to analyze the properties of j unction arrays. In particular, an effective action is obtained which enable s us to describe the array at an arbitrary temperature. In the low-temperat ure limit, our theory yields the correct, dynamically screened Coulomb inte raction of a normal metal, whereas at high temperatures the standard descri ption in terms of quantum dissipation is recovered.