Vortices in atomic-molecular Bose-Einstein condensates

The structure and stability of vortices in hybrid atomic-molecular Bose-Einstein condensates is analyzed in the framework of a two-component Gross-Pitaevskii-type model that describes the stimulated Raman-induced photoassociation process. New types of topological vortex states are predicted to exist in the coherently coupled two-component condensates even without a trap, and their nontrivial dynamics in the presence of losses is demonstrated.Comment: 7 pages, 6 figure

Dipole-Mode Vector Solitons

We find a new type of optical vector soliton that originates from trapping of a dipole mode by a soliton-induced waveguide. These solitons, which appear as a consequence of the vector nature of the two component system, are more stable than the previously found optical vortex-mode solitons and represent a new type of extremely robust nonlinear vector structure.Comment: Four pages with five eps figure

Observation of dipole-mode vector solitons

We report on the first experimental observation of a novel type of optical vector soliton, a {\em dipole-mode soliton}, recently predicted theoretically. We show that these vector solitons can be generated in a photorefractive medium employing two different processes: a phase imprinting, and a symmetry-breaking instability of a vortex-mode vector soliton. The experimental results display remarkable agreement with the theory, and confirm the robust nature of these radially asymmetric two-component solitary waves.Comment: 4 pages, 8 figures; pictures in the PRL version are better qualit

Efficacy of Various Regimens of Inhibitor-Protected Penicillins on the Basis of Immunospecific Mixed Saliva Proteins in Patients after Dental Implantation: a Randomized Uncontrolled Trial

Background. The available comparative studies on issues of choosing antibiotic regimen in dental implantation are often observational and describe only visible postoperative signs. More objective assessment of postoperative period and comparison of approaches requires laboratory tests. One of the methods to be used at a dental appointment is to study examination of the biochemical properties of saliva.Objective. To carry out comparative evaluation of single and prolonged regimens of amoxicillin/clavulanate administration after dental implantation indicated by nonspecific immunity in mixed saliva.Methods. A randomized uncontrolled trial of 30 partially edentulous patients was conducted. The clinical phase of the study was performed at the Department of Propaedeutics of Surgical Dentistry, MSUMD; the laboratory phase — at the Pharmacology and Biological Chemistry Departments, MSUMD, in 2021–2022. The study included patients aged 18 to 75 years, anatomically suitable for dental implant placement. Patients with somatic diseases in the decompensation stage were excluded from the study. Patients were randomized into 2 groups. The group 1 was prescribed to take amoxicillin/clavulanate pills (875+125 mg) 30 minutes before surgery. The group 2 was to take amoxicillin/clavulanate (875+125 mg) 30 minutes before surgery and then 1 pill of Amoxicillin/ Clavulanate (500+125 mg) 2 times a day for 7 days after surgery. To evaluate the efficacy of the applied antibiotic therapy, unstimulated mixed saliva was collected from all patients on an empty stomach, 1 ml before surgery and on the third day after surgery. The amount of immunoglobulins of G, M, A classes (mg/l) and б-amylase activity (IU/l) were determined spectrophotometrically in the saliva samples. Statistical processing of laboratory data was performed using Welch's t-test by means of Statistica 10 Pro (StatSoft, USA). Intergroup and intragroup differences were considered significant at p ≤ 0.05.Results. Based on the saliva proteins examined, the most pronounced difference between the patient groups was obtained for IgA. For other studied parameters of saliva, no significant difference between the groups was obtained on the third day after the surgery. However, despite the absence of a statistical difference, a tendency to a stronger increase in the amount of IgA, G, IgM, salivary amylase activity was noted for all indicators; moreover, a high correlation between immunoglobulins of class A, G, immunoglobulins of class G, M, and immunoglobulins of class A, M was revealed.Conclusion. Among patients with the prolonged regimen, the groups did not differ significantly in such saliva parameters as immunoglobulins G and M and salivary б-amylase activity, however, a tendency to a stronger increase of the mentioned immunoglobulins in the saliva of group 1 patients was revealed. The most significant difference was recorded for immunoglobulin A in saliva, the amount of which was significantly lower in the group of prolonged antibiotic administration (p < 0.05)

Nonlinear Dynamic Phenomena in Macroscopic Tunneling

Numerical simulations of the NLSE (or GPE) are presented demonstrating emission of short pulses of the matter (light) density formed in the course of tunneling in wave-guided light and/or trapped BEC. The phenomenon is observed under various conditions, for nonlinearities of different signs, zero nonlinearity included. We study, both numerically and analytically, pulsations of matter (light) remaining within the trap and use the results in order to induce emission of sequential pulses by properly narrowing the trap. This allows us to propose a mechanism for a realization of Atom Pulse Laser.Comment: 14 pages, 6 figure

Modulational instability of spinor condensates

We demonstrate, analytically and numerically, that the ferromagnetic phase of the spinor Bose-Einstein condenstate may experience modulational instability of the ground state leading to a fragmentation of the spin domains. Together with other nonlinear effects in the atomic optics of ultra-cold gases (such as coherent photoassociation and four-wave mixing) this effect provides one more analogy between coherent matter waves and light waves in nonlinear optics.Comment: 4 pages, 4 figures. Accepted for Phys. Rev. A Rapid Communication

Higher-order nonlinear modes and bifurcation phenomena due to degenerate parametric four-wave mixing

We demonstrate that weak parametric interaction of a fundamental beam with its third harmonic field in Kerr media gives rise to a rich variety of families of non-fundamental (multi-humped) solitary waves. Making a comprehensive comparison between bifurcation phenomena for these families in bulk media and planar waveguides, we discover two novel types of soliton bifurcations and other interesting findings. The later includes (i) multi-humped solitary waves without even or odd symmetry and (ii) multi-humped solitary waves with large separation between their humps which, however, may not be viewed as bound states of several distinct one-humped solitons.Comment: 9 pages, 17 figures, submitted to Phys. Rev.

The dynamics of a strongly driven two component Bose-Einstein Condensate

We consider a two component Bose-Einstein condensate in two spatially localized modes of a double well potential, with periodic modulation of the tunnel coupling between the two modes. We treat the driven quantum field using a two mode expansion and define the quantum dynamics in terms of the Floquet Operator for the time periodic Hamiltonian of the system. It has been shown that the corresponding semiclassical mean-field dynamics can exhibit regions of regular and chaotic motion. We show here that the quantum dynamics can exhibit dynamical tunneling between regions of regular motion, centered on fixed points (resonances) of the semiclassical dynamics

Dark-in-Bright Solitons in Bose-Einstein Condensates with Attractive Interactions

We demonstrate a possibility to generate localized states in effectively one-dimensional Bose-Einstein condensates with a negative scattering length in the form of a dark soliton in the presence of an optical lattice (OL) and/or a parabolic magnetic trap. We connect such structures with twisted localized modes (TLMs) that were previously found in the discrete nonlinear Schr{\"o}dinger equation. Families of these structures are found as functions of the OL strength, tightness of the magnetic trap, and chemical potential, and their stability regions are identified. Stable bound states of two TLMs are also found. In the case when the TLMs are unstable, their evolution is investigated by means of direct simulations, demonstrating that they transform into large-amplitude fundamental solitons. An analytical approach is also developed, showing that two or several fundamental solitons, with the phase shift $\pi$ between adjacent ones, may form stable bound states, with parameters quite close to those of the TLMs revealed by simulations. TLM structures are found numerically and explained analytically also in the case when the OL is absent, the condensate being confined only by the magnetic trap.Comment: 13 pages, 7 figures, New Journal of Physics (in press