Search results for "nonlinear relaxation time"

showing 5 items of 5 documents

Noisy dynamics in long and short Josephson junctions

The study of nonlinear dynamics in long Josephson junctions and the features of a particular kind of junction realized using a graphene layer, are the main topics of this research work. The superconducting state of a Josephson junction is a metastable state, and the switching to the resistive state is directly related to characteristic macroscopic quantities, such as the current the voltage across the junction, and the magnetic field through it. Noise sources can affect the mean lifetime of this superconducting metastable state, so that noise induced effects on the transient dynamics of these systems should be taken into account. The long Josephson junctions are investigated in the sine-Gor…

Transient dynamickinkmean switching timeSettore FIS/02 - Fisica Teorica Modelli E Metodi Matematicigraphenebreathernoise induced effectlong Josephson junctiondynamic resonant activationGaussian noisenoise enhanced stabilitysine-Gordonshort Josephson junctionnonlinear relaxation timeJosephson junctionJosephson junction; sine-Gordon; Transient dynamics; noise induced effect; noise enhanced stability; dynamic resonant activation; stochastic resonant activation; resonant activation; soliton; breather; kink; Gaussian noise; non Gaussian noise; graphene; short Josephson junction; long Josephson junction; mean switching time; nonlinear relaxation time;stochastic resonant activationresonant activationnon Gaussian noisesoliton
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Statistics of residence time for Lévy flights in unstable parabolic potentials

2020

We analyze the residence time problem for an arbitrary Markovian process describing nonlinear systems without a steady state. We obtain exact analytical results for the statistical characteristics of the residence time. For diffusion in a fully unstable potential profile in the presence of Lévy noise we get the conditional probability density of the particle position and the average residence time. The noise-enhanced stability phenomenon is observed in the system investigated. Results from numerical simulations are in very good agreement with analytical ones.

Steady stateSettore FIS/02 - Fisica Teorica Modelli E Metodi Matematicinoise-enhanced stability nonlinear relaxation time stochastic processes Lévy noiseMarkov process01 natural sciencesStability (probability)010305 fluids & plasmasNonlinear systemsymbols.namesakeLévy flight0103 physical sciencessymbolsConditional probability densityStatistical physicsDiffusion (business)010306 general physicsResidence time (statistics)Mathematics
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Nonlinear relaxation phenomena in metastable condensed matter systems

2016

Nonlinear relaxation phenomena in three different systems of condensed matter are investigated. (i) First, the phase dynamics in Josephson junctions is analyzed. Specifically, a superconductor-graphene-superconductor (SGS) system exhibits quantum metastable states, and the average escape time from these metastable states in the presence of Gaussian and correlated fluctuations is calculated, accounting for variations in the the noise source intensity and the bias frequency. Moreover, the transient dynamics of a long-overlap Josephson junction (JJ) subject to thermal fluctuations and non-Gaussian noise sources is investigated. Noise induced phenomena are observed, such as the noise enhanced s…

Josephson effectQuantum noise enhanced stabilityGeneral Physics and AstronomyThermal fluctuationslcsh:AstrophysicsDouble-well potential01 natural sciences7. Clean energySettore FIS/03 - Fisica Della Materia010305 fluids & plasmasOpen quantum systemsMetastabilityMetastabilityJosephson junctionlcsh:QB460-4660103 physical sciencesSpin polarized transport in semiconductorsddc:530lcsh:Science010306 general physicsSpin (physics)Quantum fluctuationNoise enhanced stabilityPhysicsmetastability; nonequilibrium statistical mechanics and nonlinear relaxation time; noise enhanced stability; Josephson junction; spin polarized transport in semiconductors; open quantum systems; quantum noise enhanced stabilityCondensed matter physicsNonequilibrium statistical mechanics and nonlinear relaxation timeJosephson junction; Metastability; Noise enhanced stability; Nonequilibrium statistical mechanics and nonlinear relaxation time; Open quantum systems; Quantum noise enhanced stability; Spin polarized transport in semiconductorsDissipationlcsh:QC1-999Open quantum systemlcsh:Qlcsh:PhysicsNoise (radio)
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Stabilization Effects of Dichotomous Noise on the Lifetime of theSuperconducting State in a Long Josephson Junction

2015

We investigate the superconducting lifetime of a long overdamped current-biased Josephson junction, in the presence of telegraph noise sources. The analysis is performed by randomly choosing the initial condition for the noise source. However, in order to investigate how the initial value of the dichotomous noise affects the phase dynamics, we extend our analysis using two different fixed initial values for the source of random fluctuations. In our study, the phase dynamics of the Josephson junction is analyzed as a function of the noise signal intensity, for different values of the parameters of the system and external driving currents. We find that the mean lifetime of the superconductive…

Josephson effectSettore FIS/02 - Fisica Teorica Modelli E Metodi MatematiciGeneral Physics and Astronomylong Josephson junctionlcsh:AstrophysicsmetastabilityPhysics and Astronomy (all)Mean switching timenonlinear relaxation timeCondensed Matter::SuperconductivityMetastabilitylcsh:QB460-466Initial value problemlcsh:ScienceSuperconductivityPhysicsCondensed matter physicsNoise (signal processing)Nonequilibrium statistical mechanicsQuantum noiseShot noiselcsh:QC1-999noise enhanced stabilitymean switchingtimenonequilibrium statisticalmechanicsNonequilibrium statistical mechaniclcsh:QDichotomous noise; Long Josephson junction; Mean switching time; Metastability; Noise enhanced stability; Nonequilibrium statistical mechanics; Nonlinear relaxation timelcsh:PhysicsLong Josephson junctiondichotomous noiseEntropy
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The bistable system: an archetypal model for complex systems

2011

Bistable systems often play the role of archetypal models to understand the dynamical behavior of complex systems. Examples range from microphysics to macrophysics, bìology, chemistry and also econophysics. Moreover the statistical mechanics is essential to study the physical properties of complex systems and to investigate stochastic systems in which the microscopic degrees of freedom behave collectively over large scales. We investigate the nonlinear relaxation in a bistable system in classical and quantum systems. (i) As a first classical system, the role of the multiplicative and additive noise in the mean life time of the metastable state of an asymmetric bistable system is investigate…

Metastable state; multiplicative noise; additive noise; stochastics dynamics; Lévy noise; nonlinear relaxation time; Feynman-Vernon functionalMetastable statemultiplicative noisenonlinear relaxation timestochastics dynamicFeynman-Vernon functionaladditive noiseLévy noise
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