Coulomb Blockade without Tunnel Junctions

Tunnel junctions are not needed to provide single electron effects in a metallic island. Eventually the tunnel junction may be replaced by an arbitrary scatterer. To formulate this in exact terms, we derive and analyze the effective action that describes an arbitrary scatterer. It is important that even a diffusive scatterer provides a sufficient isolation for single electron effects to persist. We also consider the fluctuations of the effective charging energy.