Correlated discrete transfer of single electrons in ultrasmall tunnel junctions

Recent theoretical and experimental studies have revealed a new family of effects taking place in very small tunnel junctions at low temperatures. The effects have a common origin, the correlated discrete tunneling of single electrons and/or Cooper pairs resulting from their electrostatic (“Coulomb”) interaction. This paper presents a brief review of the single-electron part of the family, including discussion of the background physics, methods of theoretical description of the new effects, experimental results, and possible applications of the new effects in analog and digital electronics.