Dynamic Properties for BEC in an Optical Cavity with Atom-Photon Nonlinear Interaction

In this paper we investigate the dynamics of physical properties of the system introduced in Dimer et al. (Phys. Rev. A 75, 013804, 2007) and Zhao et al. (Phys. Rev. A 90, 023622, 2014) consisting of an ensemble of four-level atoms in Bose-Einstein condensate (BEC) state and a single-mode quantized field in which nonlinear interaction is taken into account. In fact, we start with a four-level atom and then explain how this model can be reduced to an effective two-level one via the adiabatic elimination. Also, our presentation is free of any classical approximation and so it is fully quantized. In this regard, we introduce the dynamical Hamiltonian of the system in terms of angular momentum operators and use the Dicke model to achieve the state of atomic sub-system. After obtaining the analytical solution of the state vector associated with the quantized BEC-field system, various physical properties such as atomic population inversion, quantum statistics of the field, squeezing in atomic and field subsystems as well as the degree of entanglement between the “BEC atoms” and the “photons” are numerically evaluated. It is shown that, the nonlinear interaction and other involved parameters in the presented model can dramatically affect the dynamics of the system. The collapse-revival phenomenon in the population inversion, Mandel parameter and atomic squeezing is a superb feature of the system which can be controlled by tuning the chosen parameters. Meanwhile, we propose an efficient way for the generation of sub-Poissonian and squeezed fields as well as squeezed atoms via nonlinear interaction of quantized filed with atomic BEC. In addition, it is found that, after the onset of interaction the system is always entangled. Altogether, under particular conditions, the approximated sudden death and then revival of entanglement can be observed.

     

Follow up of the glassy phase formation as silicon oxide was added to Brownmillerite phase of Portland cement clinker

Brownmillerite phase is one of the four main phases of Portland cement clinker. It was prepared as pure C₄AF¹ and C₄AF with different amount of SiO₂, (5, 10, 15, 20, 25, and 40 mol%) by addition. Pure C₄AF was prepared using CaO, Al₂O₃ and Fe₂O₃ according to the ratios 4:1:1. Each sample mixture was fired at 1,400°C for 1 h then ground and introduced again to 1,400°C for 1/2 h then quenched in air. The prepared samples were ground and measured using x-ray diffraction, scanning electron microscope, A.C. conductivity and Mössbauer spectroscopy. The results were correlated and discussed. The main finding is the formation of a glassy phase besides the C₄AF structure, in addition to the formation of the C₂S phase of cement clinker as SiO₂ addition was upgraded. The electrical conductivity results showed that the 20 mol% SiO₂ sample has the lowest (σ) value.     

Weak amenability of weighted Orlicz algebras

Let G be a locally compact abelian group, \(\omega :G\rightarrow (0,\infty )\) be a weight, and (\(\Phi ,\Psi \)) be a complementary pair of strictly increasing continuous Young functions. We show that for the weighted Orlicz algebra \(L^\Phi _\omega (G)\), the weak amenability is obtained under conditions similar to the ones considered in Zhang (Proc Amer Math Soc 142:1649–1661, 2014) for weighted group algebras. Our methods can be applied to various families of weighted Orlicz algebras, including weighted \(L^p\)-spaces.     

Constructions for orthogonal designs using signed group orthogonal designs

Craigen introduced and studied signed group Hadamard matrices extensively and eventually provided an asymptotic existence result for Hadamard matrices. Following his lead, Ghaderpour introduced signed group orthogonal designs and showed an asymptotic existence result for orthogonal designs and consequently Hadamard matrices. In this paper, we construct some interesting families of orthogonal designs using signed group orthogonal designs to show the capability of signed group orthogonal designs in generation of different types of orthogonal designs.     

Effects of temperature and input energy on quasi-three-level emission cross section of Nd3+:YAG pumped by flashlamp

The influence of temperature and input energy on fluorescence emission cross section of Nd³⁺:YAG crystal is studied. The stimulated emission cross sections of quasi-three-level systems are determined in a temperature range from -30 to 60 ℃ and an input energy range from 18 to 75 J. The cross section is found to decrease with the temperature and the input energy is increased. This is attributed to the thermal broadening mechanism of the emission line. This study is relevant for the development of laser design.     

无溶剂条件下锰 (Ⅲ)-席夫碱配合物催化过氧化氢氧化醇

 Aliphatic and aromatic alcohols are efficiently oxidized to ketones or carboxylic acids using aqueous hydrogen peroxide as an oxidant in the presence of a Mn(III) Schiff-base complex as a catalyst under solvent-free conditions. The oxidation of alcohols occurred at 50 °C to give the corresponding ketones or carboxylic acids with a yield higher than 60%.