External control of dissipation in a nanometer-scale radiofrequency mechanical resonator

We demonstrate a technique by which the quality factor of a magnetically-ac tuate mechanical resonator is controlled by an external electrical circuit. Modulation of this parameter is achieved by local variation of the electri cal impedance presented to the resonator at its resonance frequency. We des cribe a theory that explains this result as arising from eddy currents in t he external electrical circuit, which are driven by electromotive forces ge nerated through motion of the resonator in the applied magnetic field. The theory is in good agreement with the induced variation in quality factor th at we observe. (C) 1999 Elsevier Science S.A. All rights reserved.