0000000000143986

AUTHOR

A. La Cognata

showing 11 related works from this author

Dynamics of two competing species in the presence of Lévy noise sources

2010

We consider a Lotka-Volterra system of two competing species subject to multiplicative alpha-stable Lévy noise. The interaction parameter between the species is a random process which obeys a stochastic differential equation with a generalized bistable potential in the presence both of a periodic driving term and an additive alpha-stable Lévy noise. We study the species dynamics, which is characterized by two different regimes, exclusion of one species and coexistence of both. We find quasi-periodic oscillations and stochastic resonance phenomenon in the dynamics of the competing species, analysing the role of the Lévy noise sources.

Competitive BehaviorComplex systemsBistabilityStochastic resonancePopulation DynamicsComplex systemModels BiologicalStochastic differential equationControl theoryQuantitative Biology::Populations and EvolutionAnimalsHumansComputer SimulationStatistical physicsEcosystemMathematicsPopulation dynamics and ecological pattern formationModels StatisticalStochastic processDynamics (mechanics)Multiplicative functionStochastic analysis methods (Fokker-Planck Langevin etc.)Adaptation PhysiologicalRandom walks and Lévy flightQuasiperiodic functionPredatory Behavior
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Design of a Lambda system for population transfer in superconducting nanocircuits

2013

The implementation of a Lambda scheme in superconducting artificial atoms could allow detec- tion of stimulated Raman adiabatic passage (STIRAP) and other quantum manipulations in the microwave regime. However symmetries which on one hand protect the system against decoherence, yield selection rules which may cancel coupling to the pump external drive. The tradeoff between efficient coupling and decoherence due to broad-band colored Noise (BBCN), which is often the main source of decoherence is addressed, in the class of nanodevices based on the Cooper pair box (CPB) design. We study transfer efficiency by STIRAP, showing that substantial efficiency is achieved for off-symmetric bias only i…

Quantum decoherenceStimulated Raman adiabatic passageFOS: Physical sciencesSINGLE COOPER PAIR ADIABATIC PASSAGE QUANTUM STATES FLUX QUBIT SPECTROSCOPY MOLECULES CIRCUIT ATOMS NOISE BOX01 natural sciencesNoise (electronics)Settore FIS/03 - Fisica Della Materia010305 fluids & plasmasSuperconductivity (cond-mat.supr-con)Quantum mechanics0103 physical sciencesMesoscale and Nanoscale Physics (cond-mat.mes-hall)010306 general physicsQuantumQuantum computerPhysicsCouplingQuantum PhysicsCondensed Matter - Mesoscale and Nanoscale PhysicsCondensed Matter - SuperconductivityCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsColors of noiseCooper pairQuantum Physics (quant-ph)
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The problem of analytical calculation of barrier crossing characteristics for Levy flights

2008

By using the backward fractional Fokker-Planck equation we investigate the barrier crossing event in the presence of Levy noise. After shortly review recent results obtained with different approaches on the time characteristics of the barrier crossing, we derive a general differential equation useful to calculate the nonlinear relaxation time. We obtain analytically the nonlinear relaxation time for free Levy flights and a closed expression in quadrature of the same characteristics for cubic potential.

Statistics and ProbabilityPhysicsexact results stochastic particle dynamics (theory)Statistical Mechanics (cond-mat.stat-mech)Differential equationEvent (relativity)Mathematical analysisFOS: Physical sciencesClosed expressionStatistical and Nonlinear PhysicsQuadrature (mathematics)Nonlinear systemLevy noiseExact resultsLévy flightStatistics Probability and UncertaintyCondensed Matter - Statistical Mechanics
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TRANSIENT DYNAMICS AND ASYMPTOTIC POPULATIONS IN A DRIVEN METASTABLE QUANTUM SYSTEM

2013

The transient dynamics of a periodically driven metastable quantum system, interacting with a heat bath, is investigated. The time evolution of the populations, within the framework of the Feynman–Vernon influ- ence functional and in the discrete variable representation, is analyzed by varying the parameters of the external driving. The results display strong non-monotonic behaviour of the populations with respect to the driving frequency.

PhysicsFluctuation phenomena random processes noise and Brownian motionDynamics (mechanics)quantum statistical methodGeneral Physics and AstronomyRELAXATIONDecoherenceSettore FIS/03 - Fisica Della MateriaNOISEQuantum systems with finite Hilbert spaceClassical mechanicsRELAXATION; NOISEMetastabilityQuantum systemTransient (oscillation)open system
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Dynamics of a Quantum Particle in Asymmetric Bistable Potential with Environmental Noise

2011

In this work we analyze the dynamics of a quantum particle subject to an asymmetric bistable potential and interacting with a thermal reservoir. We obtain the time evolution of the population distributions in both energy and position eigenstates of the particle, for different values of the coupling strength with the thermal bath. The calculation is carried out using the Feynman-Vernon functional under the discrete variable representation.

PhysicsWork (thermodynamics)Physics and Astronomy (miscellaneous)BistabilityThermal reservoirTime evolutionBistable potential; Noise Enhanced Stability; Discrete Variable Representation; Caldeira-Leggett modelNoise Enhanced StabilitySettore FIS/03 - Fisica Della MateriaBistable potentialDVRPosition (vector)Quantum mechanicsThermalNESParticleEigenvalues and eigenvectorsDiscrete Variable RepresentationCaldeira-Leggett model
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The bistable potential: An archetype for classical and quantum systems

2012

In this work we analyze the transient dynamics of three different classical and quantum systems. First, we consider a classical Brownian particle moving in an asymmetric bistable potential, subject to a multiplicative and additive noise source. We investigate the role of these two noise sources on the life time of the metastable state. A nonmonotonic behavior of the lifetime as a function of both additive and multiplicative noise intensities is found, revealing the phenomenon of noise enhanced stability. Afterward, by using a LotkaVolterra model, the dynamics of two competing species in the presence of Lévy noise sources is analyzed. Quasiperiodic oscillations and stochastic resonance pheno…

Physicsmultiplicative noiseSettore FIS/02 - Fisica Teorica Modelli E Metodi MatematiciBistabilityThermal reservoirMetastability and bistabilityStochastic resonanceTime evolutionStatistical and Nonlinear Physicsopen quantum systemsCondensed Matter PhysicsNoise (electronics)Multiplicative noisepopulation dynamicnoise enhanced stabilityQuantum mechanicsQuasiperiodic functionStatistical physicsstochastic resonanceQuantumMetastability and bistability; multiplicative noise; noise enhanced stability; stochastic resonance; population dynamics; open quantum systems
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Noise stabilization effects in models of interdisciplinary physics

2009

Metastability is a generic feature of many nonlinear systems, and the problem of the lifetime of metastable states involves fundamental aspects of nonequilibrium statistical mechanics. The investigation of noise-induced phenomena in far from equilibrium systems is one of the approaches used to understand the behaviour of physical and biological complex systems. The enhancement of the lifetime of metastable states through the noise enhanced stability effect and the role played by the resonant activation phenomenon will be discussed in models of interdisciplinary physics: (i) polymer translocation dynamics; (ii) transient regime of FitzHugh-Nagumo model; (iii) market stability in a nonlinear …

Josephson effectPhysicsmetastability in quantum systemsHistorystatistical mechanics complex systems noiseSettore FIS/02 - Fisica Teorica Modelli E Metodi MatematiciComplex systemStatistical mechanicsNoise (electronics)noise-induced phenomena; out-of-equilibrium phenomena; metastability in quantum systemsComputer Science ApplicationsEducationHeston modelNonlinear systemMetastabilityStatistical physicsout-of-equilibrium phenomenaQuantumnoise-induced phenomena
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Two competing species in super-diffusive dynamical regimes

2010

The dynamics of two competing species within the framework of the generalized Lotka-Volterra equations, in the presence of multiplicative alpha-stable Lévy noise sources and a random time dependent interaction parameter, is studied. The species dynamics is characterized by two different dynamical regimes, exclusion of one species and coexistence of both, depending on the values of the interaction parameter, which obeys a Langevin equation with a periodically fluctuating bistable potential and an additive alpha-stable Lévy noise. The stochastic resonance phenomenon is analyzed for noise sources asymmetrically distributed. Finally, the effects of statistical dependence between multiplicative …

Fluctuation phenomena random processes noise and Brownian motionPhysicsSettore FIS/02 - Fisica Teorica Modelli E Metodi MatematiciBistabilityStochastic resonanceDifferential equationLotka–Volterra equationsProbability theory stochastic processes and statisticStochastic analysis methods (Fokker-Planck Langevin etc.)Population dynamicCondensed Matter PhysicsNoise (electronics)Multiplicative noiseElectronic Optical and Magnetic MaterialsBackground noiseLangevin equationRandom walks and Levy flightQuantitative Biology::Populations and EvolutionStatistical physicsThe European Physical Journal B
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EFFECT OF LOW-FREQUENCY NOISE ON ADIABATIC PASSAGE IN A SUPERCONDUCTING NANOCIRCUIT

2011

Recent experiments have demonstrated coherent phenomena in three-level systems based on superconducting nanocircuits. This opens the possibility to detect Stimulated Raman Adiabatic Passage (STIRAP) in artificial atoms. Low-fequency noise (often 1/f) is one of the main sources of decoherence in these systems, and we study its effect on the transfer efficiency. We propose a way to analyze low frequency fluctuations in terms of fictitious correlated fluctuations of external parameters. We discuss a specific implementation, namely the Quantronium setup of a Cooper-pair box, showing that optimizing the trade-off between efficient coupling and protection against noise may allow us to observe co…

SuperconductivityPhysicsCouplingQuantum decoherenceCOOPER-PAIR BOX; STIRAP; NOISEPhysics and Astronomy (miscellaneous)Condensed matter physicsSTIRAP; quantronium; coherent transfer population; Zener transition; three-level system.three-level system.COOPER-PAIR BOXInfrasoundStimulated Raman adiabatic passageLow frequencyNoise (electronics)three-level systemSettore FIS/03 - Fisica Della MateriaNOISEZener transitionQuantum electrodynamicsSTIRAPAdiabatic processcoherent transfer populationquantronium
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Spatio-temporal behaviour of the deep chlorophyll maximum in Mediterranean Sea: Development of a stochastic model for picophytoplankton dynamics

2013

In this paper, by using a stochastic reaction-diffusion-taxis model, we analyze the picophytoplankton dynamics in the basin of the Mediterranean Sea, characterized by poorly mixed waters. The model includes intraspecific competition of picophytoplankton for light and nutrients. The multiplicative noise sources present in the model account for random fluctuations of environmental variables. Phytoplankton distributions obtained from the model show a good agreement with experimental data sampled in two different sites of the Sicily Channel. The results could be extended to analyze data collected in different sites of the Mediterranean Sea and to devise predictive models for phytoplankton dynam…

Stochastic modellingFOS: Physical sciencesStructural basinBiologyRandom processe01 natural sciencesIntraspecific competitionMediterranean sea0103 physical sciencesPhytoplanktonMarine ecosystemSpatial ecologyMarine ecosystem14. Life underwaterQuantitative Biology - Populations and Evolution010306 general physicsPhytoplankton dynamic010301 acousticsEcology Evolution Behavior and SystematicsDeep chlorophyll maximumEcologyEcological ModelingPopulations and Evolution (q-bio.PE)Spatial ecology; Marine ecosystems; Phytoplankton dynamics; Deep chlorophyll maximum; Random processes; Stochastic differential equationsSettore FIS/07 - Fisica Applicata(Beni Culturali Ambientali Biol.e Medicin)Oceanography13. Climate actionPhysics - Data Analysis Statistics and ProbabilityFOS: Biological sciencesSpatial ecologyStochastic differential equationsDeep chlorophyll maximumData Analysis Statistics and Probability (physics.data-an)
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PICOPHYTOPLANKTON DYNAMICS IN NOISY MARINE ENVIRONMENT

2012

We present a stochastic reaction-diffusion-taxis model to describe the picophytoplankton dynamics along a water column. The model, which is valid for poorly mixed waters, typical of the Mediterranean Sea, considers intraspecific competition of picophytoplankton for light and nutrients. Random fluctuations of environmental variables are taken into account by adding a source of multiplicative noise to the diffusion equation for the picophytoplankton biomass concentration, whose distribution along the water column shows a maximum at a certain depth. After converting our results into chlorophyll a concentrations, we compare theoretical distributions, obtained for different noise intensities, wi…

picophytoplankton distributionmarine environmentfluctuation phenomenarandom processepopulation dynamicSettore FIS/07 - Fisica Applicata(Beni Culturali Ambientali Biol.e Medicin)
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