Two-dimensional nonlocal vortices, multipole solitons and azimuthons in dipolar Bose-Einstein condensates

We have performed numerical analysis of the two-dimensional (2D) soliton solutions in Bose-Einstein condensates with nonlocal dipole-dipole interactions. For the modified 2D Gross-Pitaevski equation with nonlocal and attractive local terms, we have found numerically different types of nonlinear localized structures such as fundamental solitons, radially symmetric vortices, nonrotating multisolitons (dipoles and quadrupoles), and rotating multisolitons (azimuthons). By direct numerical simulations we show that these structures can be made stable.Comment: 6 pages, 6 figures, submitted to Phys. Rev.

Two-dimensional ring-like vortex and multisoliton nonlinear structures at the upper-hybrid resonance

Two-dimensional (2D) equations describing the nonlinear interaction between upper-hybrid and dispersive magnetosonic waves are presented. Nonlocal nonlinearity in the equations results in the possibility of existence of stable 2D nonlinear structures. A rigorous proof of the absence of collapse in the model is given. We have found numerically different types of nonlinear localized structures such as fundamental solitons, radially symmetric vortices, nonrotating multisolitons (two-hump solitons, dipoles and quadrupoles), and rotating multisolitons (azimuthons). By direct numerical simulations we show that 2D fundamental solitons with negative hamiltonian are stable.Comment: 8 pages, 6 figures, submitted to Phys. Plasma

Stabilization of higher-order vortices and multi-hump solitons in media with synthetic nonlocal nonlinearities

We address the evolution of higher-order excited states, such as vortex and multi-hump solitons, in nonlocal media with synthetic, competing focusing and defocusing nonlinearities with different nonlocal transverse scales. We reveal that introduction of suitable competing effects makes possible the stabilization of vortex solitons with topological charge m>2, as well as one-dimensional multi-hump solitons with number of humps p>4, all of which are highly unstable in natural nonlocal materials with focusing nonlinearities.Comment: 14 pages, 5 figures, to appear in Physical Review

Stabilization of dipole solitons in nonlocal nonlinear media

We address the stabilization of dipole solitons in nonlocal nonlinear materials by two different approaches. First, we study the properties of such solitons in thermal nonlinear media, where the refractive index landscapes induced by laser beams strongly depend on the boundary conditions and on the sample geometry. We show how the sample geometry impacts the stability of higher-order solitons in thermal nonlinear media and reveal that dipole solitons can be made dynami-cally stable in rectangular geometries in contrast to their counterparts in thermal samples with square cross-section. Second, we discuss the impact of the saturation of the nonlocal nonlinear response on the properties of multipole solitons. We find that the saturable response also stabi-lizes dipole solitons even in symmetric geometries, provided that the input power exceeds a criti-cal value.Comment: 29 pages, 8 figures, to appear in Phys. Rev.

Nonlocal stabilization of nonlinear beams in a self-focusing atomic vapor

We show that ballistic transport of optically excited atoms in an atomic vapor provides a nonlocal nonlinearity which stabilizes the propagation of vortex beams and higher order modes in the presence of a self-focusing nonlinearity. Numerical experiments demonstrate stable propagation of lowest and higher order vortices over a hundred diffraction lengths, before dissipation leads to decay of these structures.Comment: 3 figure

Stabilization of vector soliton complexes in nonlocal nonlinear media

We introduce vector soliton complexes in nonlocal Kerr-type nonlinear media. We discover that under proper conditions the combination of nonlocality and vectorial coupling has a remarkable stabilizing action on multi-humped solitons. In particular, we find that stable bound states featuring several field oscillations in each soliton component do exist. This affords stabilization of vector soliton trains incorporating large number of humps, a class of structures known to self-destroy via strong instabilities in scalar settings.Comment: 17 pages, 4 figures, to appear in Physical Review E (Rapid Communications

Stability of two-dimensional spatial solitons in nonlocal nonlinear media

We discuss existence and stability of two-dimensional solitons in media with spatially nonlocal nonlinear response. We show that such systems, which include thermal nonlinearity and dipolar Bose Einstein condensates, may support a variety of stationary localized structures - including rotating spatial solitons. We also demonstrate that the stability of these structures critically depends on the spatial profile of the nonlocal response function.Comment: 8 pages, 9 figure

Primjena frakcijske plinske analize za određivanje sadržaja oksidnih i dušičnih faza u ALNICO legurama

Fractional gas analysis procedure for estimating the contents of oxide and nitride inclusions in Alnico alloys produced from wastes of production is developed. The effect of the temperature and time of melt holding before pouring on the content of impurity oxide and nitride inclusions is considered. The content of SiO2 inclusions in Alnico mainly depends on the holding time before pouring and decreases with increasing holding time, whereas the content of Al2O3 inclusions decreases with increasing both temperature and time of holding. The content of TiN inclusions decreases with increasing holding time. As the holding temperature increases, the content of nitride inclusions decreases only with increasing holding time.Razrađena je metoda frakcijske plinske analize za vrednovanje oksidnih i dušičnih uključaka u ALNICO legurama, dobijenih iz gospodarskih otpada. Posmatran je utjecaj temperature i vremena zadržavanja kupke prije lijevanja. Sadržaj uključaka SiO2 uglavnom ovisi od vremena zadrške prije lijevanja i snižava se povećanjem tog vremena, istodobno se sadržaj uključaka Al2O3 smanjuje s povećavanjem i temperature i vremena zadrške. Sadržaj uključaka TiN smanjuje se povećavanjem vremena zadrške. S povećanjem temperature sadržaj dušičnih uključaka smanjuje se samo pri povećanju vremena zadrške prije lijevanja

Fractional gas analysis procedure for determining the contents of oxide and nitride phases in ALNICO alloys

Fractional gas analysis procedure for estimating the contents of oxide and nitride inclusions in Alnico alloys produced from wastes of production is developed. The effect of the temperature and time of melt holding before pouring on the content of impurity oxide and nitride inclusions is considered. The content of SiO2 inclusions in Alnico mainly depends on the holding time before pouring and decreases with increasing holding time, whereas the content of Al2O3 inclusions decreases with increasing both temperature and time of holding. The content of TiN inclusions decreases with increasing holding time. As the holding temperature increases, the content of nitride inclusions decreases only with increasing holding time