Search results for " NOISE"

showing 10 items of 659 documents

Noise-induced effects in nonlinear relaxation of condensed matter systems

2015

Abstract Noise-induced phenomena characterise the nonlinear relaxation of nonequilibrium physical systems towards equilibrium states. Often, this relaxation process proceeds through metastable states and the noise can give rise to resonant phenomena with an enhancement of lifetime of these states or some coherent state of the condensed matter system considered. In this paper three noise induced phenomena, namely the noise enhanced stability, the stochastic resonant activation and the noise-induced coherence of electron spin, are reviewed in the nonlinear relaxation dynamics of three different systems of condensed matter: (i) a long-overlap Josephson junction (JJ) subject to thermal fluctuat…

PhysicsJosephson effectCondensed matter physicsStochastic processSpin polarised transport in semiconductorGeneral MathematicsApplied MathematicsQuantum noiseStochastic analysis methodsShot noiseGeneral Physics and AstronomyThermal fluctuationsResonant activationStatistical and Nonlinear PhysicsNoise processes and phenomenaSpin polarised transport in semiconductorsJosephson junctionMathematics (all)Coherent statesStochastic analysis methodSpin (physics)Noise enhanced stabilityJosephson junction; Noise enhanced stability; Noise processes and phenomena; Resonant activation; Spin polarised transport in semiconductors; Stochastic analysis methodsCoherence (physics)Chaos, Solitons & Fractals
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Non-Gaussian noise effects in the dynamics of a short overdamped Josephson junction

2010

The role of thermal and non-Gaussian noise on the dynamics of driven short overdamped Josephson junctions is studied. The mean escape time of the junction is investigated considering Gaussian, Cauchy-Lorentz and Levy-Smirnov probability distributions of the noise signals. In these conditions we find resonant activation and the first evidence of noise enhanced stability in a metastable system in the presence of Levy noise. For Cauchy-Lorentz noise source, trapping phenomena and power law dependence on the noise intensity are observed.

PhysicsJosephson effectCondensed matter physicsnoise-induced effectGaussianQuantum noiseShot noiseRandom walk; noise-induced effects; Lévy noise; Josephson junctionRandom walkCondensed Matter PhysicsStability (probability)Power lawSettore FIS/03 - Fisica Della MateriaElectronic Optical and Magnetic MaterialsLévy noisesymbols.namesakeGaussian noiseJosephson junctionsymbolsNoise (radio)
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EFFECTS OF COLORED NOISE IN SHORT OVERDAMPED JOSEPHSON JUNCTION

2008

We investigate the transient dynamics of a short overdamped Josephson junction with a periodic driving signal in the presence of colored noise. We analyze noise induced henomena, specifically resonant activation and noise enhanced stability. We find that the positions both of the minimum of RA and maximum of NES depend on the value of the noise correlation time tau_c. Moreover, in the range where RA is observed, we find a non-monotonic behavior of the mean switching time as a function of the correlation time tau_c.

PhysicsJosephson effectPhysics and Astronomy (miscellaneous)Condensed matter physicsCondensed Matter - SuperconductivityFOS: Physical sciencesResonant activationJosephson junction; Colored noise; Resonant activation; Noise enhanced stabilityColored noiseStability (probability)SignalSettore FIS/03 - Fisica Della MateriaSuperconductivity (cond-mat.supr-con)Switching timeColors of noiseJosephson junctionRange (statistics)Transient (oscillation)Noise enhanced stabilityNoise (radio)International Journal of Quantum Information
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Effects of Lévy noise on the dynamics of sine-Gordon solitons in long Josephson junctions

2015

We numerically investigate the generation of solitons in current-biased long Josephson junctions in relation to the superconducting lifetime and the voltage drop across the device. The dynamics of the junction is modelled with a sine-Gordon equation driven by an oscillating field and subject to an external non-Gaussian noise. A wide range of $\alpha$-stable L\'evy distributions is considered as noise source, with varying stability index $\alpha$ and asymmetry parameter $\beta$. In junctions longer than a critical length, the mean switching time (MST) from superconductive to the resistive state assumes a values independent of the device length. Here, we demonstrate that such a value is direc…

PhysicsJosephson effectStatistics and ProbabilityCondensed Matter - SuperconductivityDynamics (mechanics)large deviations in non-equilibrium systemsLarge deviations in non-equilibrium systems; mesoscopic systems (theory); metastable states; stochastic processes (theory); Statistics and Probability; Statistical and Nonlinear Physics; Statistics Probability and UncertaintyStatistical and Nonlinear Physicsstochastic processes (theory)metastable state01 natural sciencesSettore FIS/03 - Fisica Della Materia010305 fluids & plasmasLevy noiseQuantum mechanicsLarge deviations in non-equilibrium systemmesoscopic systems (theory)Condensed Matter::Superconductivitymetastable states0103 physical scienceslarge deviations in non-equilibrium systems; mesoscopic systems (theory); metastable states; stochastic processes (theory)SineStatistics Probability and Uncertainty010306 general physicsStatistical and Nonlinear Physic
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Suppression of timing errors in short overdamped Josephson junctions

2004

The influence of fluctuations and periodical driving on temporal characteristics of short overdamped Josephson junction is analyzed. We obtain the standard deviation of the switching time in the presence of a dichotomous driving force for arbitrary noise intensity and in the frequency range of practical interest. For sinusoidal driving the resonant activation effect has been observed. The mean switching time and its standard deviation have a minimum as a function of driving frequency. As a consequence the optimization of the system for fast operation will simultaneously lead to minimization of timing errors.

PhysicsJosephson effectSuperconductivityFluctuation phenomena random processes noise and Brownian motionStatistical Mechanics (cond-mat.stat-mech)Numerical analysisCondensed Matter - SuperconductivityGeneral Physics and AstronomyFOS: Physical sciencesStatistical mechanicsFunction (mathematics)Standard deviationSwitching timeSuperconductivity (cond-mat.supr-con)Range (statistics)Statistical physicsStochastic analysis methods Fokker-Planck equation Langevin equationCondensed Matter - Statistical MechanicsSuperconducting device
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Noise induced effects in overdamped Josephson junction in the presence of colored noise

2007

We analyze the role of the correlated fluctuations, with a correlation time τc, in the dynamics of an overdamped Josephson junction in the presence of a periodic driving signal.

PhysicsJosephson effectmean switching timeJosephson phaseCondensed matter physicsNoise inducedJosephson junction; mean switching time; colored noiseNoise (electronics)SignalSettore FIS/03 - Fisica Della MateriaPi Josephson junctioncolored noiseColors of noiseCondensed Matter::SuperconductivityJosephson junctionElectronic engineeringSuperconducting tunnel junction
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Noise enhanced stability in magnetic systems

2009

In this paper noise enhanced stability in magnetic systems is studied by both an Ising-type model and a Preisach–Arrhenius model as well as a dynamic Preisach model. It is shown that in one nonequilibrium Ising system noise enhanced stability occurs and that dynamic Preisach model has the capability to predict the occurrence of noise enhanced stability in magnetic systems. On the contrary, in a Preisach–Arrhenius model of a single quadrant magnetic material, noise enhanced stability is not detected.

PhysicsMagnetic noiseCondensed matter physicsIsing systemGeneral Physics and AstronomyNon-equilibrium thermodynamicsSettore ING-IND/32 - Convertitori Macchine E Azionamenti ElettriciCondensed Matter::Disordered Systems and Neural NetworksElectric Machines Power Systems Electric TechnologyMagnetizationMagnetCondensed Matter::Statistical MechanicsIsing modelStatistical physics
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Human contrast sensitivity in coherent Maxwellian view: effect of coherent noise and comparison with speckle.

1997

Lasers have been used in vision for measuring the neural contrast sensitivity function (CSF) by forming interference fringes on the retina. We distinguish among three kinds of illumination with lasers: incoherent (without noise), Maxwellian or coherent (with coherent noise), and diffuse coherent (with speckle). The three have different characteristics and different CSF's. A coherent imaging system is designed to measure the CSF with fully coherent illumination. This is the CSF of the whole visual system, although it is measured with gratings imaged on the retina. It therefore differs from the neural CSF's measured by other authors with partially coherent illumination. However, the neural CS…

PhysicsMasking (art)business.industrymedia_common.quotation_subjectSpeckle noiseRefraction OcularLuminanceAtomic and Molecular Physics and OpticsRetinaElectronic Optical and Magnetic MaterialsContrast SensitivitySpeckle patternNoiseOpticsImage Processing Computer-AssistedContrast (vision)HumansComputer Vision and Pattern RecognitionSpatial frequencySpeckle imagingbusinessMathematicsmedia_commonJournal of the Optical Society of America. A, Optics, image science, and vision
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Approximate analytical mean-square response of an impacting stochastic system oscillator with fractional damping

2017

The paper deals with the stochastic dynamics of a vibroimpact single-degree-of-freedom system under a Gaussian white noise. The system is assumed to have a hard type impact against a one-sided motionless barrier, located at the system's equilibrium. The system is endowed with a fractional derivative element. An analytical expression for the system's mean squared response amplitude is presented and compared with the results of numerical simulations.

PhysicsMean squareMechanical EngineeringDynamics (mechanics)Degrees of freedom (physics and chemistry)White noise01 natural sciences010305 fluids & plasmasClassical mechanics0103 physical sciencesStatistical physicsSafety Risk Reliability and Quality010301 acousticsSafety Research
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Line Features in Psds of X-Ray Binaries

1994

There is a great deal of evidence that the X-ray emission from High Mass X-Ray Binaries (HMXRB) is often associated with the accretion of matter from a “normal” companion to a degenerate (neutron) star. Provided the magnetic field in these systems is very high (B ~ 1012 — 1013 G), the accretion should occur via the formation of discrete “blobs” which should emit through bremsstrahlung process due to the sudden stop near the surface of the neutron star[2, 3, 5]. There are a number of detections of non-Poissonian aperiodic variations in the intensity of emitted radiation (often referred to as “flickering”) with a characteristic Power Spectrum Density (PSD) broad band feature (red noise)[4, 1]…

PhysicsNeutron starAccretion (meteorology)Astrophysics::High Energy Astrophysical PhenomenaShot noiseBremsstrahlungAstrophysics::Solar and Stellar AstrophysicsAstronomySpectral densityNeutronRadiationLine (formation)
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