947 research outputs found
Dark soliton past a finite-size obstacle
We consider the collision of a dark soliton with an obstacle in a
quasi-one-dimensional Bose condensate. We show that in many respects the
soliton behaves as an effective classical particle of mass twice the mass of a
bare particle, evolving in an effective potential which is a convolution of the
actual potential describing the obstacle. Radiative effects beyond this
approximation are also taken into account. The emitted waves are shown to form
two counterpropagating wave packets, both moving at the speed of sound. We
determine, at leading order, the total amount of radiation emitted during the
collision and compute the acceleration of the soliton due to the collisional
process. It is found that the radiative process is quenched when the velocity
of the soliton reaches the velocity of sound in the system
Influence of the passive region on Zero Field Steps for window Josephson junctions
We present a numerical and analytic study of the influence of the passive
region on fluxon dynamics in a window junction. We examine the effect of the
extension of the passive region and its electromagnetic characteristics, its
surface inductance and capacitance. When the velocity in the passive region
is equal to the Swihart velocity (1) a one dimensional model describes
well the operation of the device. When is different from 1, the fluxon
adapts its velocity to . In both cases we give simple formulas for the
position of the limiting voltage of the zero field steps. Large values of
inductance and capacitance lead to different types of solutions which are
analyzed.Comment: 12 pages, 13 figure
Korteweg-de Vries description of Helmholtz-Kerr dark solitons
A wide variety of different physical systems can be described by a relatively small set of universal equations. For example, small-amplitude nonlinear Schrödinger dark solitons can be described by a Korteweg-de Vries (KdV) equation. Reductive perturbation theory, based on linear boosts and Gallilean transformations, is often employed to establish connections to and between such universal equations. Here, a novel analytical approach reveals that the evolution of small-amplitude Helmholtz–Kerr dark solitons is also governed by a KdV equation. This broadens the class of nonlinear systems that are known to possess KdV soliton solutions, and provides a framework for perturbative analyses when propagation angles are not negligibly small. The derivation of this KdV equation involves an element that appears new to weakly nonlinear analyses, since transformations are required to preserve the rotational symmetry inherent to Helmholtz-type equations
Lattice solitons in quasicondensates
We analyze finite temperature effects in the generation of bright solitons in
condensates in optical lattices. We show that even in the presence of strong
phase fluctuations solitonic structures with well defined phase profile can be
created. We propose a novel family of variational functions which describe well
the properties of these solitons and account for the non-linear effects in the
band structure. We discuss also the mobility and collisions of these localized
wave packets.Comment: 4 pages, 2 figure
Two-color discrete localized modes and resonant scattering in arrays of nonlinear quadratic optical waveguides
We analyze the properties and stability of two-color discrete localized modes
in arrays of channel waveguides where tunable quadratic nonlinearity is
introduced as a nonlinear defect by periodic poling of a single waveguide in
the array. We show that, depending on the value of the phase mismatch and the
input power, such two-color defect modes can be realized in three different
localized states. We also study resonant light scattering in the arrays with
the defect waveguide.Comment: 10 pages, 3 figures, published in PR
Energy localization, Fano resonances, and nonlinear meta-optics
This paper reflects on some memories of the research topics developed at Department No. 29 of the Institute for Low Temperature Physics and Engineering in Kharkov more than 30 years ago. It also provides some recent advances on my major research activities related to those topics, including energy localization and solitons in nonlinear lattices, Fano resonances in photonics and phononics, and nonlinear effects in meta-optics and nanophotonics. Curiously enough, each of those topics can be associated with some memories and discussions that happened in Kharkov a long time ago
Self-localization of a small number of Bose particles in a superfluid Fermi system
We consider self-localization of a small number of Bose particles immersed in
a large homogeneous superfluid mixture of fermions in three and one dimensional
spaces. Bosons distort the density of surrounding fermions and create a
potential well where they can form a bound state analogous to a small polaron
state. In the three dimensional volume we observe the self-localization for
repulsive interactions between bosons and fermions. In the one dimensional case
bosons self-localize as well as for attractive interactions forming, together
with a pair of fermions at the bottom of the Fermi sea, a vector soliton. We
analyze also thermal effects and show that small non-zero temperature affects
the pairing function of the Fermi-subsystem and has little influence on the
self-localization phenomena.Comment: 7 pages, 7 fiqures, improved versio
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