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S Boccaletti

Publications and source records attributed to S Boccaletti.

At least 37 records · Page 2Linked to original sources
PubMed2004

Detecting local synchronization in coupled chaotic systems.

We introduce a technique to detect and quantify local functional dependencies between coupled chaotic systems. The method estimates the fraction of locally synchronized configurations, in a pair of signals with an arbitrary state of global synchronization. Application to a pair of interacting Rössler oscillators shows that our method is able to quantify the number of dynamical configurations where a local prediction task is possible, as well as in the absence of global synchronization features.

Journal Article↗
PubMed2004

Frequency entrainment of nonautonomous chaotic oscillators.

We give evidence of frequency entrainment of dominant peaks in the chaotic spectra of two coupled chaotic nonautonomous oscillators. At variance with the autonomous case, the phenomenon is here characterized by the vanishing of a previously positive Lyapunov exponent in the spectrum, which takes place for a broad range of the coupling strength parameter. Such a state is studied also for the case of chaotic oscillators with ill-defined phases due to the absence of a unique center of rotation. Different phase synchronization indicators are used to circumvent this difficulty.

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PubMed2003

Competition of synchronization domains in arrays of chaotic homoclinic systems.

We investigate the response of an open chain of bidirectionally coupled chaotic homoclinic systems to external periodic stimuli. When one end of the chain is driven by a periodic signal, the system propagates a phase synchronization state in a certain range of coupling strengths and external frequencies. When two simultaneous forcings are applied at different points of the array, a rich phenomenology of stable competitive states is observed, including temporal alternation and spatial coexistence of synchronization domains.

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PubMed2003

Asymmetric coupling effects in the synchronization of spatially extended chaotic systems.

We analyze the effects of asymmetric couplings in setting different synchronization states for a pair of unidimensional fields obeying complex Ginzburg-Landau equations. Novel features such as asymmetry enhanced complete synchronization, limits for the appearance of phase synchronized states, and selection of the final synchronized dynamics are reported and characterized.

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PubMed2003

Constructive effects of noise in homoclinic chaotic systems.

Many chaotic oscillators have coherent phase dynamics but strong fluctuations in the amplitudes. At variance with such a behavior, homoclinic chaos is characterized by quite regular spikes but strong fluctuation in their time intervals due to the chaotic recurrence to a saddle point. We study influences of noise on homoclinic chaos. We demonstrate both numerically and experimentally on a CO2 laser various constructive effects of noise, including coherence resonance, noise-induced synchronization in uncoupled systems and noise-enhanced phase synchronization, deterministic resonance with respect to signal frequency, and stochastic resonance versus noise intensity in response to weak signals. The peculiar sensitivity of the system along the weak unstable manifold of the saddle point underlines the unified mechanism of these nontrivial and constructive noise-induced phenomena.

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PubMed2003

Noise-enhanced synchronization of homoclinic chaos in a CO2 laser.

Many chaotic oscillators have rather coherent phase dynamics but strong fluctuation in the amplitudes. Conversely, homoclinic chaos is characterized by quite regular spikes but strong fluctuation in their time intervals. We study the effects of noise on the synchronization of homoclinic chaos to a weak periodic signal and demonstrate numerically and experimentally in a CO2 laser system that noise enhances synchronization of homoclinic chaos. The system exhibits both conventional resonance versus driving frequency and stochastic resonance with respect to noise intensity.

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PubMed2003

Information encoding in homoclinic chaotic systems.

We present a simple method for real-time encoding of information in the interspike intervals of a homoclinic chaotic system. The method has been experimentally tested on a CO2 laser with feedback displaying Sil'nikov chaos and synchronized with an external pulsed signal. Information is encoded by the length of the temporal intervals between consecutive pulses of the external signal. This length is varied each time a new pulse is generated.

Carbon Dioxide↗
PubMed2003

Control of localized structures in an optical feedback interferometer.

We report a detailed experimental investigation of the dependence of localized structures, observed in a nonlinear optical device, on several control parameters. A first step of the study consists in the determination of the region of existence of localized states as a function of the system variables. Subsequently, we show how different control parameters can be used to the aim of tuning several localized structures properties; among these, of particular relevance are the contrast and the amplitude and frequency of the oscillations appearing on the tails of the structures. A discussion of the relation between the localized states here studied and the one predicted by general model for pattern forming systems is also given.

Biophysical Phenomena↗
PubMed2003

Controlling transient dynamics to communicate with homoclinic chaos.

A control that stabilizes the transient dynamics of a homoclinic chaotic laser is used to encode discrete sources of information. The controlled trajectory is a complex spiking signal that has a constrained interspike interval, and therefore, the ratio of information transmitted is approximately constant. We also show that the controlled signal that encodes the source contains more information than the source. This property is advantageously used to correct possible errors in the transmission, or to increase the ratio of information per transmitted spike.

Carbon Dioxide↗
PubMed2002

Experimental characterization of the transition to phase synchronization of chaotic CO2 laser systems.

We investigate the transition route to phase synchronization in a chaotic laser with external modulation. Such a transition is characterized by the presence of a regime of periodic phase synchronization, in which phase slips occur with maximal coherence in the phase difference between output signal and external modulation. We provide the first experimental evidence of such a regime and demonstrate that it occurs at the crossover point between two different scaling laws of the intermittent-type behavior of phase slips.

Journal Article↗
PubMed2002

Tailoring the profile and interactions of optical localized structures.

We experimentally demonstrate the broad tunability of the main features of optical localized structures (LS's) in a nonlinear interferometer. By discussing how a single LS depends on the system spatial frequency bandwidth, we show that a modification of its tail leads to the possibility of tuning the interactions between LS pairs, and thus the equilibrium distances at which LS bound states form. This is in agreement with a general theoretical model describing weak interactions of LS in nonlinear dissipative systems.

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PubMed2002

Collective phase locked states in a chain of coupled chaotic oscillators.

We discuss the emergence of a collective phase locked state in an open chain of N unidirectionally weakly coupled nonidentical chaotic oscillators. Such a regime is characterized by a Lyapunov spectrum where N-1 exponents that were zero in the uncoupled regime assume negative values as the coupling strength increases. The dynamics of such collective state is studied, and a comparison is drawn with the case of phase synchronization of a pair of coupled chaotic oscillators. In particular, it is shown that a full phase synchronized state cannot be constructed without at least partial correlation in the chaotic amplitudes.

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PubMed2002

Reconstructing embedding spaces of coupled dynamical systems from multivariate data.

A method for reconstructing dimensions of subspaces for weakly coupled dynamical systems is offered. The tool is able to extrapolate the subspace dimensions from the zero coupling limit, where the division of dimensions as per the algorithm is exact. Implementation of the proposed technique to multivariate data demonstrates its effectiveness in disentangling subspace dimensionalities also in the case of emergent synchronized motions, for both numerical and experimental systems.

Journal Article↗
PubMed2001

Unifying framework for synchronization of coupled dynamical systems.

A definition of synchronization of coupled dynamical systems is provided. We discuss how such a definition allows one to identify a unifying framework for synchronization of dynamical systems, and show how to encompass some of the different phenomena described so far in the context of synchronization of chaotic systems.

Journal Article↗
PubMed2001

Topological defects after a quench in a Bénard-Marangoni convection system.

We report experimental evidence of the fact that, in a Bénard-Marangoni conduction-convection transition, the density of defects in the emerging structure scales as a power law in the quench time needed for the control parameter to ramp through the threshold. The obtained scaling exponents differ from the ones predicted and observed in the case in which the defects correspond to zeros in the amplitude of the global two-dimensional field.

Journal Article↗
PubMed2000

Experimental phase synchronization of a chaotic convective flow.

We report experimental evidence of phase synchronization of high dimensional chaotic oscillators in a laboratory experiment. The experiment consists of a thermocapillary driven convective cell in a time dependent chaotic regime. The synchronized states emerge as a consequence of a localized temperature perturbation to the heater. The transition to phase synchronization is studied as a function of the external perturbations. The existence and stability conditions for this phenomenon are discussed.

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