Mario E. Inchiosa

Array enhanced stochastic resonance: Implications for signal processing

In computer simulations, we enhance the response of a ‘‘stochastic resonator’’ by coupling it into an array of identical resonators. We relate this array enhanced stochastic resonance (AESR) to the global spatiotemporal dynamics of the array and show how noise and coupling cooperate to organize spatial order, temporal periodicity, and peak output signal‐to‐noise ratio. We consider the application of AESR to signal processing.

Nonlinear dynamics in a high‐gain amplifier: the dc SQUID

We study the detection of very weak time-periodic magnetic signals via a double-junction (dc) Superconducting Quantum Interference Device (SQUID). The device, represented by two coupled nonlinear differential equations for the quantum mechanical junction phase differences, admits long-time static or oscillatory solutions, the transition between them being easily controlled by experimentally accessible parameters. Gain is maximal when the device is tuned to the onset of the oscillatory solutions; i.e., when the minima in the 2D potential function disappear. We concentrate on the SQUID dynamics near this critical point and compute the oscillation frequency via a center manifold reduction of the full 2D dynamics. Knowing this frequency permits its exploitation as a detection/classification tool in magnetic remote sensing applications.

Noise-mediated cooperative behavior and signal detection in dc SQUIDs

We study the detection of very weak time-periodic magnetic signals via a double-junction (dc) Superconducting Quantum Interference Device (SQUID). The device, represented by two coupled nonlinear differential equations for the quantum mechanical junction phases, admits of long-time static or oscillatory solutions, the transition being controllable by experimental parameters. Signal detection is optimal when the device is “tuned” to the onset of the oscillatory solutions; i.e., when the minima in the 2D potential function disappear. Modeling the device via a derived input-output transfer characteristic yields a response (quantified via the signal-to-noise ratio at the signal frequency) in good agreement with recent experiments. We also present some preliminary results pertaining to coupled dc SQUIDs, taking into account the (incoherent) thermal noise sources in each of the Josephson junctions. As might be expected from previous work, coupling the SQUIDs and/or summing their outputs enhances the response to...

Noise-induced synchronized switching in coupled bistable systems

We consider a network of bistable dynamic elements with local, linear coupling, subject to noise and a time periodic signal. The response (quantified by an output signal to noise ratio, SNR) of a single element can be substantially enhanced when it is coupled into an array of like elements. In fact we show that noise and coupling cooperate to organize spatio temporal order across the array, corresponding to an increase in the output SNR of the reference element. The results shed new light on the potentially beneficial role of background noise in nonlinear dynamic devices and networks of neuron like elements.