Two-color interference stabilization of atoms

The effect of interference stabilization is shown to exist in a system of two atomic levels coupled by a strong two-color laser field, the two frequencies of which are close to a two-photon Raman-type resonance between the chosen levels, with open channels of one-photon ionization from both of them. We suggest an experiment, in which a rather significant (up to 90%) suppression of ionization can take place and which demonstrates explicitly the interference origin of stabilization. Specific calculations are made for H and He atoms and optimal parameters of a two-color field are found. The physics of the effect and its relation with such well-known phenomena as LICS and population trapping in a three-level system are discussed.Comment: the paper includes 1 TeX file and 16 picture

Upper bounds for the number of orbital topological types of planar polynomial vector fields "modulo limit cycles"

The paper deals with planar polynomial vector fields. We aim to estimate the number of orbital topological equivalence classes for the fields of degree n. An evident obstacle for this is the second part of Hilbert's 16th problem. To circumvent this obstacle we introduce the notion of equivalence modulo limit cycles. This paper is the continuation of the author's paper in [Mosc. Math. J. 1 (2001), no. 4] where the lower bound of the form 2^{cn^2} has been obtained. Here we obtain the upper bound of the same form. We also associate an equipped planar graph to every planar polynomial vector field, this graph is a complete invariant for orbital topological classification of such fields.Comment: 23 pages, 5 figure

Cosmic ray modulation in a random anisotropic magnetic field

Inhomogeneities of the interplanetary magnetic field can be divided into small scale and large scale ones as may be required by the character of the problem of cosmic ray (CR) propagation. CR propagation in stochastic magnetic fields is of diffusion character. The main contribution into the scattering of CR particles is made by their interaction with inhomogeneities of the magnetic field H which have characteristic dimensions 1 of the order of Larmor radius R=cp/eH of particle (p is the absolute value of particle momentum, e is particle charge, c is velocity of light). Scattering of particles on such inhomogeneities leads to their diffusion mostly along a magnetic field with characteristic dimensions of variation in space exceeding the mean free path

Spectral and polarization effects in deterministically nonperiodic multilayers containing optically anisotropic and gyrotropic materials

Influence of material anisotropy and gyrotropy on optical properties of fractal multilayer nanostructures is theoretically investigated. Gyrotropy is found to uniformly rotate the output polarization for bi-isotropic multilayers of arbitrary geometrical structure without any changes in transmission spectra. When introduced in a polarization splitter based on a birefringent fractal multilayer, isotropic gyrotropy is found to resonantly alter output polarizations without shifting of transmission peak frequencies. The design of frequency-selective absorptionless polarizers for polarization-sensitive integrated optics is outlined