Dynamics of matter-wave and optical fields in superradiant scattering from Bose-Einstein condensates

We study superradiant scattering off Bose-Einstein condensates by solving the semiclassical Maxwell-Schroedinger equations describing the coupled dynamics of matter-wave and optical fields. Taking the spatial dependence of these fields along the condensate axis into account, we are able to reproduce and explain many of the characteristic features observed in the experiments of Inouye et al. [Science 285, 571 (1999)] and Schneble et al. [Science 300, 475 (2003)], such as the shape of the atomic side-mode distributions for forward and backward scattering, the spatial asymmetry between forward and backward side modes, and the depletion of the condensate center observed for forward scattering.Comment: 4 pages, 2 figure

A possibility for precise Weinberg angle measurement in centrosymmetric crystals with axis

We demonstrate that parity nonconserving interaction due to the nuclear weak charge Q_W leads to nonlinear magnetoelectric effect in centrosymmetric paramagnetic crystals. It is shown that the effect exists only in crystals with special symmetry axis k. Kinematically, the correlation (correction to energy) has the form H_PNC ~ Q_W (E,[B,k])(B,k), where B and E are the external magnetic and electric fields. This gives rise to magnetic induction M_PNC ~ Q_W {k(B,[k,E]) + [k,E](B,k)}. To be specific we consider rare-earth trifluorides and, in particular, dysprosium trifluoride which looks the most suitable for experiment. We estimate the optimal temperature for the experiment to be of a few kelvin. For the magnetic field B = 1 T and the electric field E = 10 kV/cm, the expected magnetic induction is 4 \pi M_PNC = 0.5 * 10^-11 G, six orders of magnitude larger than the best sensitivity currently under discussion. Dysprosium has several stable isotopes, and so, comparison of the effects for different isotopes provides possibility for precise measurement of the Weinberg angle.Comment: 7 pages, 1 figure, 2 tables; version 2 - added discussion of neutron distribution uncertaint

Spatial effects in superradiant Rayleigh scattering from Bose-Einstein condensates

We present a detailed theoretical analysis of superradiant Rayleigh scattering from atomic Bose-Einstein condensates. A thorough investigation of the spatially resolved time-evolution of optical and matter-wave fields is performed in the framework of the semiclassical Maxwell-Schroedinger equations. Our theory is not only able to explain many of the known experimental observations, e.g., the behavior of the atomic side-mode distributions, but also provides further detailed insights into the coupled dynamics of optical and matter-wave fields. To work out the significance of propagation effects, we compare our results to other theoretical models in which these effects are neglected.Comment: 14 pages, 13 figure

Counting and computing regions of DD-decomposition: algebro-geometric approach

New methods for $D$-decomposition analysis are presented. They are based on topology of real algebraic varieties and computational real algebraic geometry. The estimate of number of root invariant regions for polynomial parametric families of polynomial and matrices is given. For the case of two parametric family more sharp estimate is proven. Theoretic results are supported by various numerical simulations that show higher precision of presented methods with respect to traditional ones. The presented methods are inherently global and could be applied for studying $D$-decomposition for the space of parameters as a whole instead of some prescribed regions. For symbolic computations the Maple v.14 software and its package RegularChains are used.Comment: 16 pages, 8 figure

Causal signal transmission by quantum fields. IV: The causal Wick theorem

Wick's theorem in the Schwinger-Perel-Keldysh closed-time-loop formalism is written in a form where the place of contractions is taken by the linear response function of the field. This result demonstrates that the physical information supplied by Wick's theorem for operators is propagation of the free field in space and time.Comment: Final version, to appear in Phys Rev

МЕДИКО-ТЕХНИЧЕСКИЕ ТРЕБОВАНИЯ К МЕДИЦИНСКИМ МОНИТОРАМ ДЛЯ МАММОГРАФИЧЕСКИХ ИССЛЕДОВАНИЙ

Purpose: determination of technical characteristics when choosing medical viewing monitors, affecting the quality of the viewed image.Materials and methods: Analysis of current regulatory documents, domestic and world scientific  literature, regulatory parameters for medical viewing monitors.Results and discussions: In Russian and foreign publications, there are few articles on the assessment and analysis of medical monitors, and there are no regulatory documents. According to the technical documentation of medical viewing monitors presented in Russia, the basic requirements for medical  viewing monitors that are used when working on modern digital mammography systems have been  formed. The article analyzes the main parameters of monitors that affect the quality of the visualized image, also highlights the main parameters of digital detectors installed on mammographs and gives recommendations for choosing a medical monitor that meets the parameters of the mammograph. The main parameters for monitors are highlighted, such as resolution, brightness to contrast ratio, response time, which, if properly correlated, significantly improve the quality of work of a radiologist.Conclusions. Medical viewing monitors should meet the physico-technical parameters of the installed mammograph; to improve the quality of the work of radiologists involved in the diagnosis of mammary glands within the framework of one health care facility, it is advisable to choose medical viewing  monitors of one manufacturer; maintenance of medical viewing monitors should be performed at least twice a year.Цель: определение технических характеристик при выборе медицинских просмотровых мониторов, влияющих на качество просматриваемого изображения.Материалы и методы. Анализ действующих нормативных документов, отечественной и мировой научной литературы, регламентирующих параметров для медицинских просмотровых мониторов.Результаты и их обсуждение. В российской и зарубежной литературе встречаются единичные публикации, посвященные оценке и анализу медицинских мониторов, а нормативные документы отсутствуют. По данным технической документации представленных в России медицинских просмотровых мониторов были сформированы основные требования, предъявляемые к медицинским просмотровым мониторам, используемые при работе на современных цифровых маммографических системах. В статье проанализированы основные параметры мониторов, влияющие на качество визуализируемого изображения, выделены основные параметры цифровых детекторов, установленных на маммографах, и даны рекомендации для выбора медицинского монитора, отвечающего параметрам маммографа. Выделены основные параметры для мониторов, такие как разрешающая способность, соотношение яркости и контрастности, время отклика, которые при правильном соотношении в значительной степени повышают качество работы врача-рентгенолога.Заключение. Медицинские просмотровые мониторы должны отвечать физико-техническим параметрам установленного маммографа; для повышения качества работы врачей-рентгенологов, занимающихся диагностикой молочных желез в рамках одного ЛПУ целесообразно выбирать медицинские просмотровые мониторы одной фирмы-производителя; техническое обслуживание медицинских просмотровых мониторов следует осуществлять не реже двух раз в год

Energy levels and lifetimes of Gd IV and enhancement of the electron dipole moment

We have calculated energy levels and lifetimes of 4f7 and 4f6 5d configurations of Gd IV using Hartree-Fock and configuration interaction methods. This allows us to reduce significantly the uncertainty of the theoretical determination of the electron electric dipole moment (EDM) enhancement factor in this ion and, correspondingly, in gadolinium-containing garnets for which such measurements were recently proposed. Our new value for the EDM enhancement factor of Gd+3 is -2.2 +- 0.5. Calculations of energy levels and lifetimes for Eu~III are used to control the accuracy.Comment: Submitted to Phys. Rev. A 6 pages, 0 figures, 3 table

Searches for violation of fundamental time reversal and space reflection symmetries in solid state experiments

The electric dipole moment (EDM) of a particle violates both time reversal (T) and space reflection (P) symmetries. There have been recent suggestions for searches of the electron EDM using solid state experiments [1,2]. These experiments could improve the sensitivity compared to present atomic and molecular experiments by several orders of magnitude. In the present paper we calculate the expected effect. We also suggest that this kind of experiment is sensitive to T,P-violation in nuclear forces and calculate effects caused by the nuclear Schiff moment. The compounds under consideration contain magnetic Gd$^{3+}$ ions and oxygen O$^{2-}$ ions. We demonstrate that the main mechanism for the T,P-odd effects is related to the penetration of the Oxygen 2p-electrons to the Gd core. All the effects are related to the deformation of the crystal lattice.Comment: 13 pages, 6 figure

Self-Organization in Multimode Microwave Phonon Laser (Phaser): Experimental Observation of Spin-Phonon Cooperative Motions

An unusual nonlinear resonance was experimentally observed in a ruby phonon laser (phaser) operating at 9 GHz with an electromagnetic pumping at 23 GHz. The resonance is manifested by very slow cooperative self-detunings in the microwave spectra of stimulated phonon emission when pumping is modulated at a superlow frequency (less than 10 Hz). During the self-detuning cycle new and new narrow phonon modes are sequentially ``fired'' on one side of the spectrum and approximately the same number of modes are ``extinguished'' on the other side, up to a complete generation breakdown in a certain final portion of the frequency axis. This is usually followed by a short-time refractority, after which the generation is fired again in the opposite (starting) portion of the frequency axis. The entire process of such cooperative spectral motions is repeated with high degree of regularity. The self-detuning period strongly depends on difference between the modulation frequency and the resonance frequency. This period is incommensurable with period of modulation. It increases to very large values (more than 100 s) when pointed difference is less than 0.05 Hz. The revealed phenomenon is a kind of global spin-phonon self- organization. All microwave modes of phonon laser oscillate with the same period, but with different, strongly determined phase shifts - as in optical lasers with antiphase motions.Comment: LaTeX2e file (REVTeX4), 5 pages, 5 Postscript figures. Extended and revised version of journal publication. More convenient terminology is used. Many new bibliographic references are added, including main early theoretical and experimental papers on microwave phonon lasers (in English and in Russian

Non-Linear Algebra and Bogolubov's Recursion

Numerous examples are given of application of Bogolubov's forest formula to iterative solutions of various non-linear equations: one and the same formula describes everything, from ordinary quadratic equation to renormalization in quantum field theory.Comment: LaTex, 21 page