Efficient Images Storage Due to a Microwave Field in a Cold Four-Level Atomic System

International Journal of Theoretical Physics - Quantum memories that are able to store arbitrary two-dimensional images offer advantages over light pulses memories, in terms of both speed and...     

Losses in pendular suspensions due to centrifugal coupling

We present an analysis of the centrifugal coupling of a simple pendulum to a dissipative support. We show that such a coupling leads to an amplitude dependent quality factor. For amplitudes which could be present in laser interferometer gravitational wave detector suspensions, this mechanism could limit the quality factor of the test mass suspension significantly to 10¹⁰ and should be considered in the design of advanced LIGO type detectors.     

Possibility of Using a Multilayer Target to Reduce Losses of Tritium in a Neutron Tube

The ability of yttria layers to act as barriers to hydrogen desorption is studied. The possibility is discussed of using these layers to reduce losses of tritium from a neutron tube target. The composition of a multilayer target in which tritium desorption is reduced by an accumulator layer (zirconium) and barrier layers (yttria) is described. It is shown that deuterium losses observed in thermal desorption tests over 4 h at 623 K fell by 85–87%. A system is proposed for the renewal of an external barrier layer subjected to sputtering by a deuteron ion flux.     

Theoretical Study of Polarized Optical Bistability Due to Rydberg State in a Four-Level Atomic System under External Magnetic Field

International Journal of Theoretical Physics - In this paper, we proposed a model based on Rydberg atoms for controlling the optical bistability (OB) and optical multistability (OM) in a ring...     

调制不稳定性对级联放大光纤传输系统信噪比的影响

在考虑光纤损耗和级联放大器的情况下，推导了调制不稳定性的产生条件和增益的普适解析表达式，分析了调制不稳定性对信噪比的影响，给出了一个新的计算信噪比的表达式。     

Energy Losses of a Charged Particle due to Excitation of Helicons in Plasma-Like Media

We study the energy lost by a particle moving along the helical line in a static magnetic field due to Vavilov–Cherenkov radiation of volume and surface helicons. It is found that the energy losses related to excitation of volume helicons are equivalent to the energy losses of a magnetic moment created due to the charge rotation. The magnetic moment moves at a constant velocity along the magnetic field. It is shown that collisionless damping of volume helicons in plasmas is based on the Cherenkov radiation of magnetic moment. Radiation of surface helicons by a particle does not correspond to the energy losses of a moving magnetic moment. This is related to the fact that not only magnetic (H) waves but also electric (E) waves contribute to the excitation of surface helicons, which leads to an increase in the energy losses of a particle.     

Rapidity Losses in Heavy-Ion Collisions from AGS to RHIC Energies

We study the rapidity losses in central heavy-ion collisions from ACS to RHIC encrgolcs with the mean rapidity determined from the projectile net-baryon distribution after collisions. The projectile net-baryon distribution in the full rapidity range is obtained by phenomenologically removing the target contribution at the forward rapidity region from the experimental net-baryon measurements and taking into account the projectile contribution in the backward rapidity region. Based on the full projectile net-baryon distributions, calculations show that the rapidity loss stops increasing from the SPS top energy to RHIC energies, indicating that baryon transport does not depend strongly on energy at high energies.     

Enhancement of Second-Harmonic Generation in a Micropillar Resonator Due to the Engineered Destructive Interference

JETP Letters - We show that engineering the cavity aspect ratio of AlGaAs micropillar resonator allows for the two orders of magnitude increase in the efficiency of second harmonic generation at...     

Modal Birefringence Dependent Supercontinuum Due to Cross-Phase Modulation in a Dispersion-Flattened/Decreasing Fiber

It was found by numerical analysis that a 320 nm wide and flat spectrum at 20 dB less than the central maximum intensity is generated from cross-phase modulated soliton pulses with 3.5 ps pulse width and 2.3 W peak power, which are propagated through a 2.4km length of dispersion-flattened/decreasing fiber (DFDF). The cross-phase modulation (XPM) at a central wavelength of 1.55 μm is achieved by exciting two orthogonally polarized modes into the principal axes. The wave-vector mismatch between the orthogonal pulses can be neglected because of soliton trapping when the modal birefringence of the DFDF is less than |n_ox - n_0y| = 10⁻⁶. The effect of modal birefringence on supercontinuum generation is discussed in temporal and spectral regimes by numerical analysis.     

An MHD Effect on a Newtonian Fluid Flow Due to a Superlinear Stretching Sheet

The preliminary aim of this article is to investigate the effect of magnetohydrodynamic (MHD) flows of a viscous fluid due to a superlinear stretching sheet. These boundary layer flows arise in the industrial processes such as polymer extrusion processes, metal spinning, glass blowing and heat exchangers. The representing frameworks of highly nonlinear partial differential equations are mapped to nonlinear ordinary differential equations with a constant coefficient via similarity transformation and are solved analytically. The results are analyzed by means of various plots to provide the comparison and found to be in better agreement with the classical results of Crane and Pavlov. The viscous fluid due to a superlinear stretching sheet in the presence ofMHDhas enormous amount of nonlinearity in conducting the solution area with different arrangements.     

Supercritical Density Modifications of a Laser-Produced Plasma Due to Resonant Cavity Fields

A laser plasma is produced at the center of a cylindrical cavity while radio-frequency excitation of moderate power is supplied near the TM011 and TE111 vacuum-mode frequencies. Probe and particle collector measurements show density modification of the plasma during its decay due to resonances excited by the RF source. The magnitudes of these density changes are found to be near and exceeding critical (?p = ?RF) density.     

Entropies of a Toroidal Black Hole Due to Scalar and Dirac Fields

Using the thin film brick-wall model, the entropies of a toroidal black hole due to scalar and Dirac fields are investigated. The entropy due to the scalar field is one fourth of the horizon area, and that due to the Dirac field is seven eighth of the area. These results are similar to that in black holes with horizon topology S ². The cutoff in toroidal black hole is chosen as the same as one in black holes with horizon topology S ², which seems to mean that the thin film brick-wall model is universal.     

Non-Markovian Dynamics of a Localized Electron Spin Due to the Hyperfine Interaction

We review our theoretical work on the dynamics of a localized electron spin interacting with an environment of nuclear spins. Our perturbative calculation is valid for arbitrary polarization p of the nuclear spin system and arbitrary nuclear spin I in a sufficiently large magnetic field. In general, the electron spin shows rich dynamics, described by a sum of contributions with exponential decay, nonexponential decay, and undamped oscillations. We have found an abrupt crossover in the long-time spin dynamics at a critical shape and dimensionality of the electron envelope wave function. We conclude with a discussion of our proposed scheme to measure the relevant dynamics using a standard spin–echo technique.     

南京地区实际气溶胶对臭氧探测的影响

本文研究了在实测的南京地区五种气溶胶分布下,大气气溶胶对三波长差分吸收激光雷达(Dual-DIAL)臭氧探测结果的影响,使用波长对266nm,289nm,308nm进行了误差分析。通过对实际气溶胶的误差分析,模拟出在大部分高度上误差最小的C值(为消去后向散射及消光项误差引入的比值)C=1.7,并与传统方法取得的C=23/19进行了对比。讨论了气溶胶分布及含量对C值选取的影响及不同C值下误差随气溶胶变化的规律;分析得出对于本文所使用的气溶胶分布以及波长对,取C=1.7时在气溶胶较均匀时误差接近于零,误差不会大于5%,当气溶胶变化率变高且频繁变化时误差最大可达40%。取C=23/19时误差很稳定,不随气溶胶分布变化,误差高度增加误差减小且小于10%。本文还讨论了不同气溶胶分布下C的选取方法。     

Charge Ordering Due to Antiferromagnetic Correlation in Quarter-Filled Manganites

In the present paper, we study the zero-temperature phase diagram of the doped perovskite manganites at filling $x=0.5$ by the real-space Hartree-Fock approximation method. Our purpose is to resolve a controversial issue arising recently on the origin of the charge ordered phases in these systems. We find that the antiferromagnetic superexchange interaction between the localized spins plays the central role in producing the concerned phases. Our results confirm some speculations on this issue.     

Charge Ordering Due to Antiferromagnetic Correlation in Quarter-Filled Manganites

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Effective Gradients in Porous Media Due to Susceptibility Differences

In porous media, magnetic susceptibility differences between the solid phase and the fluid filling the pore space lead to field inhomogeneities inside the pore space. In many cases, diffusion of the spins in the fluid phase through these internal inhomogeneities controls the transverse decay rate of the NMR signal. In disordered porous media such as sedimentary rocks, a detailed evaluation of this process is in practice not possible because the field inhomogeneities depend not only on the susceptibility difference but also on the details of the pore geometry. In this report, the major features of diffusion in internal gradients are analyzed with the concept of effective gradients. Effective gradients are related to the field inhomogeneities over the dephasing length, the typical length over which the spins diffuse before they dephase. For the CPMG sequence, the dependence of relaxation rate on echo spacing can be described to first order by a distribution of effective gradients. It is argued that for a given susceptibility difference, there is a maximum value for these effective gradients,g_max, that depends on only the diffusion coefficient, the Larmor frequency, and the susceptibility difference. This analysis is applied to the case of water-saturated sedimentary rocks. From a set of NMR measurements and a compilation of a large number of susceptibility measurements, we conclude that the effective gradients in carbonates are typically smaller than gradients of current NMR well logging tools, whereas in many sandstones, internal gradients can be comparable to or larger than tool gradients.     

Transient Waves Due to Mechanical Loads in Elasto-Thermo-Diffusive Solids

This paper deals with the study of transient waves in a homogeneous isotropic, solid half-space with a permeating substance in the context of the theory of generalized elasto-thermodiffusion. The half-space is assumed to be disturbed due to mechanical loads acting on its boundary. The model comprising of basic governing differential equations and boundary conditions has been solved by employing Laplace transform technique. Noting that the second sound effects are short lived, the small time approximations of solution for various physical quantities have been obtained and the results are discussed on the possible wave fronts. In case of continuous and periodic loads acting at the boundary, the displacement is found to be continuous at each wave front while it is discontinuous in case of impulsive load. The temperature and concentration fields are found to be discontinuous at all the wave fronts. The displacement, temperature change and concentration deviation due to impulsive, continuous and periodic mechanical loads have also been evaluated in the physical domain at all times by employing numerical inversion technique of integral transform. The computer simulated numerical results have been presented graphically in respect of displacement, temperature change and concentration deviation for brass. A significant effect of mass diffusion has been observed on the behaviour of mechanical and thermal waves.