Suppression of noise in a noisy optical trap

We have experimentally explored and clarified the concept of noise suppression in intrinsically noisy systems by adding noise at the input using a microscopic bead held in a moving and intensity-modulated optical trap. By coupling the stiffness of the optical trap to its position, we have explicitly constructed an experimental model system in which added fluctuations in the trap position result in reduced variance of the observed bead position as compared to a stationary trap. This reduction in variance and the spectral properties of the observed output noise agree with theoretical predictions. Our experiment demonstrates that the essential aspect of noise reduction in such a system is that the added fluctuations drive the system into states with a reduced intensity of intrinsic noise sufficiently often.