Experimentally controlled stochastic resonance in a superconducting quantum interferometer

Abstract

The stochastic resonance effect is observed experimentally in a niobium superconducting quantum interferometer (RF SQUID loop) and manifests itself in a non-monotonic rise of the gain of a weak low-frequency harmonic signal which peaks at a certain level of Gaussian quasi-white noise flux inside the loop. It is shown experimentally that the gain of the weak harmonic signal can be varied and maximized when the noise flux intensity is insufficient to realize the SR condition by introducing a deterministic ac magnetic flux into the loop, the ac flux frequency highly exceeding the useful signal frequency.