Vol 37, No 1 (2016)

We study the problem of a time-dependent nonuniform magnetic field in the Heisenberg chain. We consider two cases: a single two-level atom and N-level atoms affecting by the magnetic field. We obtain the wave function and use it for calculating the expectation values of the dynamical operators, more precisely, the atomic inversion, in order to study the phenomena of revivals and collapses. Furthermore, we obtain the expectation value of other operators of the SU(2) group and discuss the phenomenon of squeezing. We show that the phase angle η and the detuning parameter δ are the most substantial parameters of the model under consideration.

Recently photon-added states that could be detected through the emission rather than the absorption of electromagnetic radiation have been actively explored and investigated. In this paper, we construct the photon-added power-law-potential coherent states (PA-PLPCSs) using generalized Heisenberg algebra. The Klauder minimal set of conditions required to obtain coherent states are satisfied. We study nonclassical effects associated with PA-PLCSs using the Mandel parameter and discuss some of their intriguing nonclassical behavior. These states have interesting significance and can be realized experimentally, exhibiting highly nonclassical behavior that depends on the degree of excitation and other parameters. Finally, we study the dynamics of entanglement and quantum discord for two-mode state within the framework of PLPCSs and show that the sudden death and sudden birth of correlations are due to the change and transfer of the correlation between one mode and its environment, using the monogamic relation between the entanglement and quantum discord.

Aerosols influence the radiation budget of the Earth’s atmospheric system. Aerosol particle size distribution is one of the major parameters used for characterizing aerosol influence on radiative forcing. The optical and microphysical properties of aerosol particles over Yinchuan, China, were measured with a multiwavelength lidar developed at Beifang University of Nationalities using backscatter and extinction coefficients at wavelengths of 1064, 532, and 355 nm. These data were used to retrieve particle size distributions. Given the disadvantages of the traditional regularization method, the innovative multipopulation genetic algorithm (MPGA) was used to retrieve the particle size distribution from the lidar data. To verify the feasibility of using the MPGA on multiwavelength lidar data, experiments were carried out under different atmospheric conditions, including a background sunny day, a cloudy day, and a foggy day. The particle size distributions obtained from the multiwavelength lidar data were compared with results retrieved from direct irradiance data from a sun photometer. Results showed that the MPGA is suitable for retrieving particle size distributions from multiwavelength lidar data.

We elaborate a modern approach to the temperature diagnostics of a Z-pinch plasma. The approach is based on quantum-mechanical calculations of spectral brightness for X-ray radiation performed in a large interval of the photon energy for several temperatures and densities. In a large interval of the photon energy, a range can be found where the spectral brightness is highly sensitive to the temperature variation. This fact enables temperature diagnostics without complicated analysis of the spectral-line shape used in traditional diagnostic methods. In our calculations of the spectral brightness of X-ray radiation, we use a theoretical model known as the ion model of a plasma. We discuss important features of this model along with the other theoretical models used for calculating the radiative properties of the plasma. We calculate the spectral brightness of X-ray radiation for molybdenum plasma at temperatures of 1 and 1.2 keV and plasma densities of 1 and 2 g/cm³ and find the range of X-ray radiation energies that can be used for the temperature diagnostics.

We demonstrate a full-optical two-channel system for measuring mechanical vibrations of microoscillators, which is based on adaptive holographic interferometer using multiwave mixing in a photorefractive crystal. The orthogonal geometry of dynamic hologram recording makes possible independent operation of the measurement channels. The absolute detection limit of the system to cantilever vibrations in a channel amounted to 2.6·10⁻⁶ nm·W^1/2·Hz^−1/2. We tested the system in simultaneous detection of vibrations of two cantilevers with dimensions 215×40×15 μm.