-
[show abstract]
[hide abstract]
ABSTRACT: Using a semi-classical model to describe the interaction between coherent electromagnetic radiation and a Bose-Einstein condensate in the limit of zero temperature, including the back action of the atoms on the radiation, we have analyzed the phenomenon of emission of solitary-like wave packets which can accompany the formation of mutually localized atom-laser structures. Comment: 7 pages, 10 figures manuscript to be submitted to PRA
08/2010;
-
[show abstract]
[hide abstract]
ABSTRACT: The collective behaviour of neutrinos and anti neutrinos is analysed within the framework of a semi-classical model. Neutrinos close to thermal equilibrium are described by a coupled system of Schrödinger equations with nonlinear asymmetric selfinteraction potentials. The nonlinearity allows for dark soliton formation. It is shown that the interaction of incoherent neutrinos can be modelled by a coupled system of nonlinear Vlasov equations. The latter is analysed perturbatively, and a dispersion relation is derived.
Physica Scripta 07/2006; 2004(T107):36. · 1.20 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Within the framework of the thermal wave model, an investigation is made of the longitudinal dynamics of high-energy charged-particle beams. The model includes the nonlinear self-consistent interaction between the beam and its surroundings in terms of a coupling impedance, and when resistive as well as reactive parts are included, the evolution equation becomes a generalized nonlinear Schrödinger equation including a nonlocal nonlinear term. The consequences of the resistive part on the propagation of particle bunches are examined using analytical as well as numerical methods.
Physical Review E 07/2004; 69(6 Pt 2):066501. · 2.26 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We analyze the collective behavior of neutrinos and antineutrinos in a dense background. Using the Wigner transform technique, it is shown that the interaction can be modelled by a coupled system of nonlinear Vlasov-like equations. From these equations, we derive a dispersion relation for neutrino-antineutrino interactions on a general background. The dispersion relation admits a novel modulational instability. The results are examined, together with a numerical example, and we discuss the induced density inhomogeneities using parameters relevant to the early Universe.
07/2003;
-
[show abstract]
[hide abstract]
ABSTRACT: A statistical multistream description of quantum plasmas is formulated, using the Wigner-Poisson system as dynamical equations. A linear stability analysis of this system is carried out, and it is shown that a Landau-like damping of plane wave perturbations occurs due to the broadening of the background Wigner function that arises as a consequence of statistical variations of the wave function phase. The Landau-like damping is shown to suppress instabilities of the one- and two-stream type.
Physical Review E 05/2002; 65(4 Pt 2B):046417. · 2.26 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We apply the concepts of nonlinear guided-wave optics to a Bose-Einstein condensate (BEC) trapped in an external potential. As an example, we consider a parabolic double-well potential and derive coupled-mode equations for the complex amplitudes of the BEC macroscopic collective modes. Our equations describe different regimes of the condensate dynamics, including the nonlinear Josephson effect for any separation between the wells. We demonstrate macroscopic self-trapping for both repulsive and attractive interactions, and confirm our results by numerical simulations. Comment: 4 pages, 5 figures; typos removed, figures amended; submitted to PRA
10/1999;
-
[show abstract]
[hide abstract]
ABSTRACT: Approximate similarity solutions are given for the problem of electric field penetration into a plasma with a nonlinear current saturating conductivity.
IEEE Transactions on Plasma Science 07/1981; · 1.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The effect of the Kerr nonlinearity on linear non-diffractive Bessel beams is investigated analytically and numerically using the nonlinear Schrödinger equation. The nonlinearity is shown to primarily affect the central parts of the Bessel beam, giving rise to radial compression or decompression depending on whether the nonlinearity is focusing or defocusing, respectively. The dynamical properties of Gaussian-truncated Bessel beams are also analysed in the presence of a Kerr nonlinearity. It is found that although a condition for width balance in the root-mean-square sense exists, the beam profile becomes strongly deformed during propagation and may exhibit the phenomena of global and partial collapse.
Optics Communications.
-
[show abstract]
[hide abstract]
ABSTRACT: In quantum electrodynamics, photon–photon scattering can be the result of the exchange of virtual electron–positron pairs. Effectively, this gives rise to self-interaction terms in Maxwell's equations, similar to the nonlinearities due to polarization in nonlinear optics. These self-interaction terms vanish in the limit of parallel propagating waves. However if the modes generated in bounded regions are used, there will be a nonzero total effect. We show that stationary two-dimensional light bullets can form in guiding structures, due to the balancing effect of quantum electrodynamical vacuum nonlinearities on dispersion and diffraction. These light bullets are unstable and exhibit the possibility of self-focusing collapse. The consequences of our results are also discussed.
Physics Letters A.
