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Purpose. As a standard model for describing the processes of a resonant transmission of quantum information on arbitrary distances is the system of two identical two-level atoms, one of which is under radiation of the field of real photons. Such a system can serve as a basis for the construction of an element basis of quantum computers. The purpose of this paper is to study the different modes of dynamics of a system of two identical two-level atoms when they interacts with the field of real photons. Methods. In this paper, we propose a general approach to the description of the processes for the transfer of quantum information from one atom-qubit to another on the arbitrary interatomic distances, which includes two types of new physical effects: the attenuation of quantum states and the retardation of the dipole-dipole interaction. Results. The optical properties of a system of two identical two-level atoms in collective (symmetric Ψ s and antisymmetric Ψ a ) Bell states at arbitrary interatomic distances are investigated. The closed analytical expressions for the shifts and widths of the considered collective states are considered, taking into account the retarded dipole-dipole interaction of atoms. In calculation of the radial matrix elements of the dipole-dipole interaction, the wave functions of the model Fues potential are used. Conclusions. A detailed study of the mechanisms of resonant transmission of the excitation energy at arbitrary distances between the two-element atoms has an important practical significance for the physical realization of the logical operator CNOT.

Purpose. The CuInP2S6 and CuInP2Se6 crystals are characterized by an order-disorder phase transition mechanism, which is caused by electron-phonon interaction and the Jan-Teller cooperative effect. Vibronic instability is related to the electronic configuration of copper d10 in octahedral symmetry, and the disorder in the paraelectric phases can be explained by the jumping movements of Cu ions. It is of interest to study the conditions of this instability at the pressure. The main aim of our paper is to carry out the investigation of the matrix of the vibronic potential energy and the adiabatic potentials at the pressure. Methods. Adiabatic potentials concept based on the group -theoretical analysis and Pikus’ method of invariants. Results. For the case of hydrostatic pressure for crystals with D3 d symmetry, an adiabatic potential depending on the components of the strain tensor and the coordinates of normal vibrations active in the Jahn-Teller effect has been obtained. We carried out the numerical simulations of the pressure effect on the shape of the adiabatic potentials From our qualitative analysis follows that the changing of the adiabatic potential depth ( EJT ) and the value of the minimum displacement ρ 0 takes place. Especially the shape of the adiabatic potential energy is changed at the shift strain exy . Conclusions. Using the symmetry methods, we constructed the matrix of the vibronic potential energy and found the adiabatic potentials. It is shown that in a consequence of the phase transition the splitting of the equivalent minima (disorder) of the adiabatic potential on the group of the nonequivalent minima (order) is occurred. The shape of these adiabatic potentials shows that in their concept one can confirm about the order-disorder phase transition and also to consider the pressure influence on these potentials.

Purpose. This article is dedicated to the study of phase shifts for single-channel neutron-proton scattering. The phase shifts, which are obtained in the variable phase approach, are studied. For the approximation of phase shifts, a function — 2019 is used in the form of a known formula for a parabolic-type quadratic function y(x)=a+bx+cx2 , which was proposed by M.A. Dolgopolov, L.A. Minin and V.A. Rabotkin in the study of phase shifts for the Paris potential. It is necessary to find the coefficients a, b, c for y(x) when approximating the np- scattering phases for the Argonne v18 potential. Methods. Approximation is used to find the coefficients of the function y(x). Find the optimal values of the coefficients a, b, c at a minimum value χ 2 . Results. An approximation of the neutron-proton scattering phases obtained by various methods for the phenomenological nucleon-nucleon potential Argonne v18 was made. The calculated coefficients of this function obtained for phase shifts by means of the variable phase approach are compared with the results of the approximation of the scattering phases from the original paper. For illustration graphs are given for phase shifts for four spin states for the np- system ( 1S0, 3P1, 1D2, 3D2). Conclusions. The obtained coefficients for the function y(x) can be used to calculate the values of the scalar scattering amplitude, the full cross-section and the partial scattering amplitude for any phase value within the energy interval for the approximation carried out. In next studies one can obtain and compare the coefficients and parameters of approximation for scattering phases for other modern phenomenological nucleon-nucleon potentials. Keywords: variable phase approach, nucleon-nucleon scattering, approximation, phase shifts, Arg

The narrow optical resonances are widely used in ultra-high-resolution spectroscopy and precision laser metrology. The paper briefly describes the basic physical principles of narrow optical resonances, examples of implementation using advanced laser systems. The "dark" resonances formed at interaction of rubidium atoms with radiation femtosecond laser and frequency-modulation resonances of nonlinear absorption and nonlinear dispersion of molecular iodine, the prospects of their application are considered. Keywords: laser, nonlinear laser spectroscopy, atom, molecule, femtosecond laser.

This paper considers the results of the two methods of determining events (dating) ceramic samples. Here we have used the absolute and relative activities of gamma-active nuclides series of 232Th and 238U, resulting from theoretical calculations and nuclear gamma-spectrometry. Key words: ceramics, events, gamma-active nuclides, nuclear gamma-spectrometry, standard set.

In present paper the frequency response and a cylindrical pendulum absorbers mechanical oscillations using trigonometric formulas of Cardano, analytical formulas and calculated values of the resonance frequencies of the absorber. Analytical relations are useful to optimize the parameters of mechanical vibration dampers on the stage of construction to ensure a more effective suppression of external disturbances.

The paper is devoted to theoretical studies of the satellite structure of He- and Ne- like lines. On the basis of a new method - relativistic perturbation theory with ab initio model zeroth approximation for three-quasiparticle systems the calculation of spectroscopic characteristics for Li-like satellite tines in spectra of He-like ions and Na-like satellite lines in spectra of Ne-like ions is carried out.

In the present paper the results experimental and theoretical investigations of superelastic scattering on the metastablc 3s3p 3 P 0,2 states of Mg represented. The experiments have been carried out on conditions of crossed electron and atomic beams. In experiment the part of integral cross section for super-elastic scattering in the range of scattering angles from 0 to ~ 0.5 rad was measured. Energy dependence of these cross sections for super-elastic scattering from metastable 3 3 P 0,2 states of Mg atom was obtained in the near-threshold region for energies from 0.15 up to 3 eV. The relative accuracy of obtained cross sections is estimated to be ~ 8%, the energy scale calibration errors are less then 0.1 eV. The resonance structure at electron energy -0.45 eV was obtained. We used R-matrix method with pseudo-states in 35-state intermediate-coupling approximation for the calculation of electron-impact excitation cross sections in neutral Mg. The close-­coupling expansion includes the 21 physical target slates and 14 pseudo-states in the LSJ coupling scheme. The good agreement in the energy dependence of experimental and theoretical cross section at energies greater than 0.4 eV, but larger difference is observed in the near-threshold region was obtained. The origin of this difference is not clear, and further both theoretical and experimental investigations are desirable in this respect.

The review of the experimental papers on investigations the isomer’s cross - section states in reactions (y,y')m excitations for the wide nuclear range at 4-20 MeV has been done. The analyzes of the peculiarities of the isomer ratios behavior at the threshold (y,n) reactions has carried out.

The systematization of physical and mechanical properties was carried out in the paper. At is pointed out at correlation of these properties with shell structure of atomic nuclei, and with influence onthem by magic of atomic nucleus. Properties in the behaviour of mechanical and physical elements in the range of atomic number 64 are supposed to have to be observed.