Stochastic Resonance in Thermally Bistable Josephson Weak Links and Micro-SQUIDs

Constriction-based Josephson weak links display a thermal bistability between two states exhibiting zero and finite voltages. This manifests in experiments either as hysteresis the current-voltage characteristics of or random telegraphic signal voltage. In latter case, noise-driven amplification sinusoidal excitation device is observed, at frequencies matching characteristic switching frequency signal, phenomenon known stochastic resonance. The observed behavior understood using two-state model resonance exploited to illustrate an enhanced signal-to-noise-ratio $\ensuremath{\mu}$-SQUID magnetic field sensor.