Dynamics of Shuttle Devices

Chapter 1 Introduction In this chapter we give a short introduction to the world of nanoelectrome- chanical systems. We then focus our attention on a particular kind of device called electron shuttle. We sketch the basic operating regime and give an overview of the different theoretical models that have been proposed to de- scribe the dynamics of such devices. We report on the two main realizations of shuttle devices and close the chapter with an outline of the contents of this thesis. 1.1 NEMS Much interest has been drawn in recent years on the concepts and realiza- tion of Nanoelectromechanical systems (NEMS). NEMS are nanoscale devices that combine mechanical and electrical dynamics in a strong interplay. This property makes them interesting both from a technological and fundamental point of view. They are extremely sensitive mass and position detectors. Due to their very high mechanical frequency one can even think of using them as the basis for new form of mechanical computers. From the point of view of fundamental research they represent extremely good tools to probe directly the basic quantum mechanical laws. They could represent the first man-made structures on which the mechanical zero point fluctuation can be detected. They also rise the question on the limiting dimension for persis- tence of mechanical coherence. In general one of the fascinating aspects of these objects is their mesoscopic character: they share with the macroscopic world the large number of atoms of which they are made (typically of millions of atoms) but on the other hand their behaviour is (or should be) already significantly determined by quantum mechanics. 11