Stochastic resonance in a superconducting loop with a Josephson junction

A simple superconducting loop with a Josephson junction subject to a time-sinusoidal magnetic flux embedded in a noise background is considered. Cooperative effects, arising from the interplay between the noise and modulation are described; they manifest themselves in the response, measured as an output signal-to-noise ratio. In particular, it is shown that the response displays the stochastic resonance effect, wherein the output signal-to-noise ratio passes through a maximum at a critical value of the noise strength. A simple theory, based on the characterization of the superconducting quantum interference device as a bistable switching element, is seen to yield good qualitative agreement with the experimental results.