Open Problems In Noise In NEMS

Nanoelectromechanical systems (NEMS) is a new technology which achieves its functionality by combining electrical transport with mechanical motion of nanoscopic bodies. The measured current-voltage characteristics does not always yield sufficient information to uniquely identify the underlying charge transport mechanism, and thus different theoretical models may result in indistinguishable predictions for the IV-characteristics. Therefore, the measurement of noise, and even the full counting statistics is viewed as an important step towards a more complete understanding of the dynamics of NEMS devices. While significant progress has been made in recent years in the theory of noise in NEMS, several open issues and challenges remain, both concerning the appropriate quantum mechanical equations to be used, their simplified semiclassical counterparts, and, finally, their numerical evaluation. We illustrate some of these issues using a quantum mechanical charge shuttle as a bench-marking system.