Controlling Stochastic Resonance

Stochastic resonance (SR) is a nonlinear noise-mediated cooperative phenomenon wherein the coherent response to a deterministic signal can be enhanced in the presence of an optimal amount of noise. Since its inception in 1981 [1], SR [2] has been demonstrated in diverse systems including sensory neurons, mammalian neuronal tissue, lasers, SQUIDs, tunnel diodes, and communications devices. Variations and extensions of the classical definition of SR to include aperiodic (e.g., dc or wideband) signals, with the detector response quantified by various information-theoretic [3] or spectral cross-correlation [4] measures, have also appeared in the literature. In this Letter, we introduce a control scheme which allows us, at will, to either enhance or suppress the spectral response in the basic SR effect. Our control strategy is applicable when input information is transmitted via the crossing of either a threshold or potential energy barrier. This raises the intriguing possibility that in situations where external signals might be potentially deleterious, e.g., electromagnetic field interactions with neuronal tissue [5], their effects could be substantially reduced or even eliminated via (externally applied) control signals. The experiments were carried out in a modified Schmitt trigger (ST) electronic circuit. The Schmitt trigger is one of the simplest threshold systems [6,7], possessing a static hysteretic nonlinearity. We denote the lower and upper threshold voltages in the Schmitt trigger by VL