Shuttling of electrons and Cooper pairs

Properties of nanocomposite materials are affected by a coupling between mechanical deformations of the materials and electronic charge transport. In one of the simplest systems of this kind, a single electron transistor (SET) with deformable tunnel barriers (nanoelectromechanical SET), mechanically assisted charge transfer becomes possible. This can be viewed as 'shuttling of single electrons' between metallic leads by a movable small-sized cluster. In this article we review some recent theoretical and experimental achievements concerning shuttle transport, in normal as well as superconducting systems.