Signal Processing and Control in Nonlinear Nanomechanical Systems

Bestriding the realms of classical and quantum mechanics, nanomechanical structures offer great promise for a huge variety of applications, from computer memory elements \cite{badzey04} and ultra-fast sensors to quantum computing. Intriguing as these possibilities are, there still remain many important hurdles to overcome before nanomechanical structures approach anything close to their full potential. With their high surface-to-volume ratios and sub-micron dimensions, nanomechanical structures are strongly affected by processing irregularities and susceptible to nonlinear effects. There are several ways of dealing with nonlinearity: exceptional fabrication process control in order to minimize the onset of nonlinear effects or taking advantage of the interesting and oftentimes counterintuitive consequences of nonlinearity. Here, we present evidence for the use of stochastic resonance as a means of coherent signal amplification for use in nanomechanical devices. Aside from being simply one more system in which the phenomenon has been demonstrated, nanoscale systems \cite{lee03} are interesting because of their proximity to the realm of quantum mechanics. The combination of stochastic resonance and quantum mechanics has been the subject of intense theoretical activities \cite{wellens00, goychuk99, grif96, lof94} for many years; nanomechanical systems present a fertile ground for the study of a broad variety of novel phenomena in quantum stochastic resonance. Additionally, the physical realization of such nonlinear nanomechanical strings offer the possibility of studying a whole class of phase transition phenomena, particularly those modeled by a Landau-Ginzburg quantum string \cite{benzi85, hu99}.