Abstract

In a large number of experiments or devices, noise is usually viewed as an undesirable disturbance, hindering the measurement sensitivity or device performances. In some circumstances however, noise-induced phenomena can help, as in the case of stochastic resonance whereby a small coherent signal gets amplified resonantly by application of external noise. Stochastic resonance occurs in a wide class of nonlinear systems, in neurobiology [1], mesoscopic physics [2], photonics [3], atomic physics [4], mechanics [5,6]… Stochastic resonance is a kind of synchronization of the switching events. If a weak periodic forcing is applied to the oscillator, the initially symmetrical double-well potential gets tilted asymmetrically up and down, periodically raising and lowering the potential barrier. Although the periodic forcing is too weak to let the membrane switch periodically from one potential well into the other one, noise-induced hopping between the potential wells can become synchronized with the weak period forcing. This time coincidence takes place when the average waiting time between noise-induced interwell transitions is comparable with half the period of the periodic forcing. Thus stochastic resonance corresponds to the noise-assisted amplification of a weak coherent input that is too feeble to induce hopping between the two stable states.

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