We consider thermodynamic and transport properties of a long granular array with strongly connected grains (inter-grain conductance g>>1.) We find that the system exhibits activated behavior of conductance and thermodynamic density of states ~exp(-T*/T) where the gap, T*, is parametrically larger than the energy at which conventional perturbation theory breaks down. The scale T* represents energy needed to create a long single-electron charge soliton propagating through the array.
@article{arxiv.cond-mat/0305246,
title = {Electron Transport in Granular Metals},
author = {Alexander Altland and Leonid I. Glazman and Alex Kamenev},
journal= {arXiv preprint arXiv:cond-mat/0305246},
year = {2009}
}