EVADING AMPLIFIER NOISE IN NONLINEAR OSCILLATORS

Resonators driven to self-oscillation via active feedback play an impo rtant role in technology. Among the stochastic processes driving phase diffusion in such oscillators is noise from the feedback amplifier. H ere a technique is described by which phase diffusion due to this nois e can be suppressed. We have achieved a 10 dB reduction in phase diffu sion by using the technique on an oscillator whose frequency-controlli ng element is a nonlinear mechanical resonator. The technique, in prin ciple, provides a quantum nondemolition method of tracking a resonator 's phase.