On the possibility of attaining the Bose-condensation region in spin-polarized atomic hydrogen at ultra-low temperatures

It is shown that the adsorption of atomic hydrogen on the He⁴ surface is predominantly accompanied by excitation of the surface wave. At ultra-low temperatures a strong decrease in the adsorption rate with temperature is found to result in a surface density of adsorbed atoms essentially lower than its equilibrium value. Therefore the channels of recombination of atomic hydrogen on the surface prove to be suppressed and it becomes possible to make compatible the Bose-condensation and the long lifetime of the spin-polarized atomic hydrogen gas.     

Manipulation of the population of hyperfine sublevels by pulsed resonance electromagnetic fields

A method has been proposed for rapidly and deeply changing the population in the system of unequally populated hyperfine atomic levels, including the ground-state sublevels, due to the impact of mutually coherent pulsed resonance electromagnetic fields. The method can be implemented, e.g., to create new schemes of the amplification or effective absorption of the radiation passing through a medium, to develop the new field of quantum electronics, spintronics, involving the current of polarized electrons, and to create new schemes of quantum computers.     

On the possibility of separating signals of pulsed ionization detectors from amplifier noise by using self-coincidences

A method for separating ionization detector pulses from amplifier noise is proposed. Two amplifiers are used. As usual, one amplifies the signal from the detector anode, while the other amplifies the signal from the cathode. Summing the signals, we obtain the total noise of both amplifiers during a pulse. Knowing the noise distribution law for each channel, we divide the noise sum integral by pairs of the noise integrals in the channels with an estimate of their probability. Subtracting the noise integral from the channel signal integral, we obtain possible values for the detector pulses with an indicator of their probabilities. A regime for continuous signal analysis without use of the coincidence scheme is also proposed.     

On the possibility of measuring magnetic fields by scattered light

In the following paper we discuss the possibility of measuring magnetic fields by scattered light. In the case of uncorrelated electrons (i.e. α ?1) the electron spectrum is modulated with the electron gyration frequency if a certain condition is fulfilled. The essential parameters are discussed and some spectra are computed numerically.     

Quantum theory of electromagnetic fields interacting with atoms and molecules

This paper reviews the recent achievements in nonrelativistic quantum electrodynamics, especially nonlinear and coherent phenomena. The general properties of coupled radiation and matter are presented within simple models in section 1. The following sections treat in some detail three main aspects of the system and can be read independently of each other. Section 2 discusses some experiments with long-wave-length radiation (r.f.) and atoms. Section 3 presents the quantum theory of a laser and the ensuing photon distributions. Section 4 treats the case of strongly correlated emission of radiation called superradiance. The use of statistical ensembles is briefly discussed in Appendix A, whereas Appendices B, C and D present some technical details of the text.     

On the possibility of using dark magneto-optical lattices to achieve Bose condensation of atoms

We show that in dark magneto-optical lattices, effects associated with the Bose statistics of atoms can be observed even at laser cooling temperatures (10⁻⁴–10⁻⁶ K), which exceed evaporative cooling temperatures in magnetic traps by several orders of magnitude. Quasicondensation occurs, i.e., the wave function is formed over the distances on which atoms are localized near the bottom of a separate potential well. In addition, switching off the magnetic field adiabatically reduces the temperature significantly, as a result of which Bose condensation in the entire volume of the gas can be observed. We propose a configuration of the light and magnetic fields in which the shape of the three-dimensional magneto-optical potential is independent of the phases of the emerging light waves. Zh. éksp. Teor. Fiz. 113, 2056–2064 (June 1998)     

闪电脉冲电磁场在地下空间的分布特性

为了研究闪电脉冲电磁场(LEMP)在地下传播的过程与空间分布特性,本文采用一种改进的时域有限差分法(FDTD)计算了LEMP在整个地下空间的传播过程.与以往发表的研究只局限在个别观察点的讨论不同,本文通过计算得到了空间中所有网格位置上的电磁场、时间导数、功率密度和能量密度及它们的峰值,并将它们按照空间坐标表示在相应的分布彩图中.发现在靠近地表和远离闪电通道的区域内,LEMP的各个分量同时在平行和垂直地面的两个方向上呈指数型衰减.其中磁场与水平电场的峰值在整个空间极性统一,且呈现类双指数形分布.而垂直电场在地下的峰值分为极性相反的两个区域,并且靠近闪电通道的区域呈类球状分布.其他特性参量也有类似以上的空间分布特点.并且本文通过对不同大地电导率、电容率、放电通道模型和基电流情况的计算,发现虽然在个别情况下LEMP在地下空间的数值整体增大,但整体分布特征并未改变.即使是在水平或垂直分层大地的情况下,同一层内部仍然具有相同的分布规律.甚至是在击中避雷针情况下,LEMP在地下空间的分布特点也仍然未变.而这些分布规律和特征的发现和利用,将为地下管线、设备、线缆的电磁防护设计与位置规划提供重要的支持.     

About a possibility of a decrease in the radiative width of excited levels of atoms and nuclei

The radiative width of quasi-energy states of a system, interacting with an external monochromatic field, is found in the present work. It is shown that a new physical effect — the formation of states with anomalous large life times — is possible in such systems.     

On the possibility of “informational” cooling of neutral atoms

A method of lowering the temperature of neutral atoms is considered. The method is based on gaining information on the translational state of individual atoms and the use of this information for the separation of slow and fast atoms. The lowest attainable temperature of an atomic ensemble is appreciably lower than the atomic recoil energy.     

On the possibility of the nucleation of magnetic vortices and antivortices in magnetic dielectrics using electric fields

The micromagnetic distribution in a dielectric nanoparticle is theoretically considered. It is shown that the presence of an inhomogeneous magnetoelectric interaction in magnetic dielectrics creates the possibility of nucleation of magnetic vortices and antivortices in them using an electric field. The estimation of the critical voltage necessary for vortex creation in particles of high-temperature multiferroic bismuth ferrite yields a value of ∼100 V.     

On the longitudinal polarization of non-paraxial electromagnetic fields

Within the framework of the angular plane-wave spectrum of the electromagnetic field, the general form is given for the freely-propagating beams, exact solution of the Maxwell equations, that closely approach (in an algebraic sense) to a purely-longitudinal vectorial distribution at some transverse plane. In the rotationally symmetric case, such a field is written as the combination of radial and longitudinal components, whose propagation can be analysed independently. Several illustrative examples are also considered.     

On electromagnetic properties of rotating nuclei in crpa

An analysis of quasiparticle correlations with special emphasis on transition matrix elements have been done for a self-consistent cranking model. It is pointed out that a second order of the boson representation of a transition operator leads to a signature dependence of transition probabilities between excited one-phonon states in even-even nuclei. Moreover, it brings about the new contribution to an expectation value of electromagnetic moments in the yrast line states of deformed nuclei.     

Measurement of the optical resonances of atoms with short-lived nuclei by using light induced drift

A new method for the measurement of the optical resonance of atoms with short-lived nuclei is proposed. one variant of a laser spectrometer based on this method is presented. The range of the nuclides suitable for the investigation by the proposed method is discussed.     

On the scaling of the paramagnetic susceptibility of atoms,nuclei and nucleons

The present status of the paramagnetic susceptibility of nuclei derived from measurements of magnetic dipole ground state transitions is reported. The values for nuclei are compared with corresponding values from atomic and nucleonic matter. It is found that the mean paramagnetic susceptibilities of atoms (typical values of metals are chosen for comparison), nuclei and nucleons scale with the corresponding Fermi energies.     

On the possibility of investigations with very cold neutrons at pulsed sources

The possibility of investigations with very cold neutrons (VCNs) using the example of the IBR-2 pulsed reactor at the JINR FLNP is considered. Possible application areas and specific features of reactor characteristics for these investigations are briefly described. The results of detailed calculations of VCN generation in different cold moderators, VCN transport in neutron guides, and suppressing the contribution of delayed neutrons are presented.     

On electromagnetic fields in the Hamiltonian description of continua

The group theoretical structure of an infinite dimensional Hamiltonian formulation of continuum mechanics is studied using as an example the Maxwell-Vlasov system. In contrast to earlier works, electromagnetism and charged matter are coupled via Poisson brackets without using the vector potential. The charged matter is described on the group of canonical transformations on R⁶ and we show that its evolution arises from a symplectic structure, modified by the magnetic field. The configurations of the electromagnetic field must be constrained by the physical requirement of the Gauss law. With the energy-functional taken as a Hamiltonian this leads - even for relativistic particles - to the well-known equations of motion.     

Scattering of atoms and molecules by an electromagnetic field

The scattering of atoms and molecules by the force of stimulated light pressure appearing in a standing wave is considered. It is shown that short (10^-8s) light pulses of tunable lasers can deviate resonance atoms through an angle of about 5°. A high selectivity of scattering is retained in a standing wave even in conditions of great saturation. Therefore the considered effect can be used for the separation of isotopes.