Abstract
Following recent insights into energy storage and loss mechanisms in nanoelectromechanical systems (NEMS), nanomechanical resonators with increasingly high quality factors are possible. Consequently, efficient, non-dissipative transduction schemes are required to avoid the dominating influence of coupling losses. Here we present an integrated NEMS transducer based on a microwave cavity dielectrically coupled to an array of doubly clamped pre-stressed silicon nitride beam resonators. This cavity-enhanced detection scheme allows resolving of the resonators' Brownian motion at room temperature while preserving their high mechanical quality factor of 290,000 at 6.6 MHz. Furthermore, our approach constitutes an 'opto'-mechanical system in which backaction effects of the microwave field are employed to alter the effective damping of the resonators. In particular, cavity-pumped self-oscillation yields a linewidth of only 5 Hz. Thereby, an adjustement-free, all-integrated and self-driven nanoelectromechanical resonator array interfaced by just two microwave connectors is realised, which is potentially useful for applications in sensing and signal processing.