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38 results on '"Barletti, L."'

1. Wigner function with correlation damping

Author

Barletti, l., Bordone, P., Demeio, L., and Giovannini, E.

Subjects
Quantum Physics
Abstract

We examine the effect of the decoherence-induced reduction of correlation length on a one-dimensional scattering problem by solving numerically the evolution equation for the Wigner function with decoherence proposed in [L. Barletti, G. Frosali and E. Giovannini, Journal of Computational and Theoretical Transport 47, 209 (2018)]. The numerical solution is achieved by the Splitting-Scheme algorithm. Three cases are examined, corresponding to a reflection-dominated regime, a transmission-dominated regime and an intermediate one. The dynamic evolution of the Wigner function is followed until the separation process of the reflected and of the transmitted packets is complete and it is observed for three different values of the correlation length. The outcomes show a broadening and flattening of the Wigner function which becomes progressively more pronounced as the correlation length is decreased. This results in a reduced reflection at low energies and in a reduced transmission at high energies., Comment: 21 pages, 13 figures

Published
2021
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2. Nonlinear electron and spin transport in semiconductor superlattices

Author

Bonilla, L. L., Barletti, L., and Alvaro, M.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Nonlinear charge transport in strongly coupled semiconductor superlattices is described by Wigner-Poisson kinetic equations involving one or two minibands. Electron-electron collisions are treated within the Hartree approximation whereas other inelastic collisions are described by a modified BGK (Bhatnaghar-Gross-Krook) model. The hyperbolic limit is such that the collision frequencies are of the same order as the Bloch frequencies due to the electric field and the corresponding terms in the kinetic equation are dominant. In this limit, spatially nonlocal drift-diffusion balance equations for the miniband populations and the electric field are derived by means of the Chapman-Enskog perturbation technique. For a lateral superlattice with spin-orbit interaction, electrons with spin up or down have different energies and their corresponding drift-diffusion equations can be used to calculate spin-polarized currents and electron spin polarization. Numerical solutions show stable self-sustained oscillations of the current and the spin polarization through a voltage biased lateral superlattice thereby providing an example of superlattice spin oscillator., Comment: 20 pages, 2 figures, to appear in SIAM J. Appl. Math

Published
2008
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4. Derivation of a Hydrodynamic Model for Electron Transport in Graphene via Entropy Maximization

Author

Barletti, L., Bock, Hans Georg, Series editor, de Hoog, Frank, Series editor, Friedman, Avner, Series editor, Gupta, Arvind, Series editor, Nachbin, André, Series editor, Ozawa, Tohru, Series editor, Pulleyblank, William R., Series editor, Rusten, Torgeir, Series editor, Santosa, Fadil, Series editor, Seo, Jin Keun, Series editor, Tornberg, Anna-Karin, Series editor, Russo, Giovanni, editor, Capasso, Vincenzo, editor, Nicosia, Giuseppe, editor, and Romano, Vittorio, editor

Published
2016
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13. Solving the Nonlinear Schrödinger Equation Using Energy Conserving Hamiltonian Boundary Value Methods.

Author

Barletti, L., Brugnano, L., Frasca Caccia, G., and Iavernaro, F.

Subjects
*HAMILTON'S equations, *BOUNDARY value problems, *NUMERICAL solutions to differential equations, *SCHRODINGER equation, *PARTIAL differential equations
Abstract

In this paper we study the use of energy-conserving methods, in the class of Hamiltonian Boundary Value Methods, for the numerical solution of the nonlinear Schrodinger equation. [ABSTRACT FROM AUTHOR]

Published
2017
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24. Correspondence between the NLS equation for optical fibers and a class of integrable NLS equations.

Author

Felice, D. and Barletti, L.

Subjects
*PAINLEVE equations, *PARTIAL differential equations, *NONLINEAR differential equations, *NONLINEAR integral equations, *SCHRODINGER equation, *WAVE mechanics, *OPTICAL fibers
Abstract

The propagation of the optical field complex envelope in a single-mode fiber is governed by a one-dimensional cubic nonlinear Schrödinger equation with a loss term. We present a result about L2-closeness of the solutions of the aforementioned equation and of a one-dimensional nonlinear Schrödinger equation that is Painlevé integrable. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2015
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33. Radiative transfer modelling in protoplanetary disks with the P-N Approximation and Monte Carlo techniques

Author

Luigi Barletti, L. Graziani, Cesare Cecchi-Pestellini, Santi Aiello, Graziani, L., Barletti, L., Aiello, S., and Cecchi-Pestellini, C.

Subjects
Field (physics), General Mathematics, Monte Carlo method, Protoplanetary disk, Monte carlo methods, P-N approximation, protoplanetary disks, radiative transfer, Engineering (all), Radiative transfer, Mathematics (all), Protostar, Statistical physics, Radiant intensity, Astrophysics::Galaxy Astrophysics, Physics, Numerical analysis, protoplanetary disks, General Engineering, Monte carlo methods, Monte carlo method, P-N approximation, Computational physics, radiative transfer, Astrophysics::Earth and Planetary Astrophysics, Intensity (heat transfer)
Abstract

A protoplanetary disk is a quasi-toroidal gas-dust mixture rotating around a protostar that creates a complex intensity field in the internal disk medium in which planets are believed to form. In this work we start to model an idealized disk describing the radiation intensity propagating along a vertical disk section using the P-N Approximation. This unidimensional approach can be extended to a flared surface case but the problem rapidly raises complexity in solving a simple cylindrical mid-plane region. The full 3D case is then handled with a Monte Carlo (MC) code reusing the idealized model to test the software reliability. The Monte Carlo lack in precision is fully repaid by the flexibility in describing the light-to-dust interaction moving the model towards a more realistic micro-physics based approach. Copyright © 2010 John Wiley & Sons, Ltd.

Published
2010
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34. Derivation of Isothermal Quantum Fluid Equations with Fermi-Dirac and Bose-Einstein Statistics

Author

Luigi Barletti, Carlo Cintolesi, Cintolesi, Carlo, Barletti L., and Cintolesi C.

Subjects
Fermi-Dirac statistics, Quantum fluid, Quantum entropy principle, Quantum hydrodynamics, Fermi-Dirac statistic, Quantum hydrodynamic, Semiclassical physics, FOS: Physical sciences, Kinetic energy, Isothermal process, symbols.namesake, Bose–Einstein statistics, Fermi–Dirac statistics, Limit (mathematics), Quantum, Mathematical Physics, Quantum drift-diffusion, Bose-Einstein statistics, Bohm potential, Mathematical physics, Physics, Statistical and Nonlinear Physics, Bose-Einstein statistic, Mathematical Physics (math-ph), symbols, 76Y05, 82C10, 82D37
Abstract

By using the quantum maximum entropy principle we formally derive, from a underlying kinetic description, isothermal (hydrodynamic and diffusive) quantum fluid equations for particles with Fermi-Dirac and Bose-Einstein statistics. A semiclassical expansion of the quantum fluid equations, up to O(h^2)-terms, leads to classical fluid equations with statistics-dependent quantum corrections, including a modified Bohm potential. The Maxwell-Boltzmann limit and the zero temperature limit are eventually discussed., Comment: 36 pages

Published
2012

35. Using Hamiltonian control to desynchronize Kuramoto oscillators.

Author

Gjata O, Asllani M, Barletti L, and Carletti T

Abstract

Many coordination phenomena are based on a synchronization process, whose global behavior emerges from the interactions among the individual parts. Often in nature, such self-organized mechanism allows the system to behave as a whole and thus grounding its very first existence, or expected functioning, on such process. There are, however, cases where synchronization acts against the stability of the system; for instance in some neurodegenerative diseases or epilepsy or the famous case of Millennium Bridge where the crowd synchronization of the pedestrians seriously endangered the stability of the structure. In this paper we propose an innovative control method to tackle the synchronization process based on the application of the Hamiltonian control theory, by adding a small control term to the system we are able to impede the onset of the synchronization. We present our results on a generalized class of the paradigmatic Kuramoto model.

Published
2017
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36. Signal-noise interaction in nonlinear optical fibers: a hydrodynamic approach.

Author

Barletti L and Secondini M

Abstract

We present a new perturbative approach to the study of signal-noise interactions in nonlinear optical fibers. The approach is based on the hydrodynamic formulation of the nonlinear Schrödinger equation that governs the propagation of light in the fiber. Our method is discussed in general and is developed in more details for some special cases, namely the small-dispersion regime, the continuous-wave (CW) signal and the solitonic pulse. The accuracy of the approach is numerically tested in the CW case.

Published
2015
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37. Stochastic amplification of spatial modes in a system with one diffusing species.

Author

Cantini L, Cianci C, Fanelli D, Massi E, Barletti L, and Asllani M

Subjects
Models, Theoretical, Morphogenesis, Stochastic Processes
Abstract

The problem of pattern formation in a generic two species reaction-diffusion model is studied, under the hypothesis that only one species can diffuse. For such a system, the classical Turing instability cannot take place. At variance, by working in the generalized setting of a stochastic formulation to the inspected problem, spatially organized patterns can develop, seeded by finite size corrections. General conditions are given for the stochastic patterns to occur. The predictions of the theory are tested for a specific case study.

Published
2014
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38. Linear noise approximation for stochastic oscillations of intracellular calcium.

Author

Cantini L, Cianci C, Fanelli D, Massi E, and Barletti L

Subjects
Stochastic Processes, Time Factors, Calcium metabolism, Calcium Signaling, Intracellular Space metabolism
Abstract

A stochastic model of intracellular calcium oscillations is analytically studied. The governing master equation is expanded under the linear noise approximation and a closed prediction for the power spectrum of fluctuations analytically derived. A peak in the obtained power spectrum profile signals the presence of stochastic, noise induced oscillations which extend also outside the region where a deterministic limit cycle is predicted to occur., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Published
2014
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