Projet ANR-06-JCJC-0036 – NEMESIS : NanoElectroMEchanical transport and Shuttling In normal and superconducting Systems
Programme : Programme "Jeunes chercheuses et jeunes chercheurs" (JCJC) 2006
Année de financement : 2006
Coordinateur du projet : CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE RHONE-ALPES SECTEUR ALPES (CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE RHONE-ALPES SECTEUR ALPES)
Partenaires : Centre national de la recherche scientifique; Centre national de la recherche scientifique; Commissariat à l'énergie atomique et aux énergies alternatives
Montant : 140000.0 euros
Date de début : 2006
Durée : 36 mois
Résumé : Nanoelectromechanical transport and shuttling in normal and superconducting systems      	 Introduction  Electromechanical devices are ubiquitous in our every day life. Electric motors, electric switches, loud speakers, accelerometers, etc. are present at all length scales and degrees of complexity. The miniaturization of these devices improves every day. The micrometer scale is already a commercial reality. From the fundamental side it is now possible to think to devices on the scale of the nanometer. These new systems are currently called NEMS, Nano Electro Mechanical Systems. The change of three orders of magnitude in their size implies many consequences [1].  In general, reducing the size of the device will increase the typical oscillation frequencies. Most mechanical devices are based on an oscillating part, which is the mechanical element. Its movement is then converted into an electric signal by a transducer, or vice-versa the transducer is used to actuate the motion of the mechanical part. In both cases the device has a typical working time that is set by the eigenfrequency of oscillation. Reducing the size of the device may tremendously increase this oscillation frequency, and thus shorten the response time. For instance the oscillation frequency of a rigid slab increases with the square of its length. Oscillators at 1 GHz have already been measured with reasonably high quality factors [2]. The reduced dimension implies also a small overall dissipation of these devices. Completely new possibilities can be envisaged. The mechanical oscillators could be used as time bases, and substitute the quartz which are large and expensive devices. Other possible applications are the treatment of high frequency electromagnetic signals, necessary for the cell phones. Bi-stable mechanical configurations (for instance a doubly clamped slab under compression) can be used as static memories. Many applications are still to be discovered. An additional advantage of the miniaturization is the increase in the sensitivity and the reduction of the spatial resolution: extremely local devices can be designed. The reduced mass, for instance, allows the realization of high sensibility mass detectors (atto-gram sensibility [3]), that have been proved to work for detecting viruses, for instance [4].  A resonator at 1 THz should display quantum effects at 50 Kelvin. It becomes thus possible to investigate quantum phenomena in objects that are intermediate between the microscopic and the macroscopic world. There are no experimental tests on that scale, and surprises could arise. Fundamental questions of quantum mechanics could be considered in a new context, with the hope of reaching a better understanding of phenomena like quantum entanglement and decoherence.  It is thus clear that mastering the electromechanics at the nanometer scale opens new perspectives, both in the applied and fundamental research. There are still many difficulties along this way. In general from the experimental point of view, the actuation and transduction of the mechanical motion, is a major problem. The amplitude of oscillation in these devices can be a fraction of Angstrom. From the theoretical point of view many questions need to be addressed. In general the study of the interplay between the mechanical motion and the electronic transport on the nanoscale is a completely new subject. The electron-phonon coupling is a well understood and deeply studied problem in solids, but the physics becomes quite different in these devices where the reduced size of the mobile parts weakens screening and increases the back action of the oscillation on the transport properties. A particularly clear and paradigmatic example of this new kind of interplay between the electronic transport properties and the mechanical degrees of freedom is represented by the charge shuttle [5].   A paradigm: The charge shuttle  The idea is very simple, let us consider a single electron transistor where the