Saint Petersburg, Russia

Herzen State Pedagogical University
Saint Petersburg, Russia

The Herzen State Pedagogical University of Russia is one of the largest universities in Russia. Located in Saint Petersburg, it operates 20 faculties and more than 100 departments. Embroidered in its structure are the Institute of Pre-University Courses, the Institute of Continuous Professional Development, and the Pedagogical Research Center. The university is named after the Russian writer and philosopher Alexander Herzen. Wikipedia.

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Paranina A.,Herzen State Pedagogical University
International Journal of GEOMATE | Year: 2017

The article shows the objective criteria of sacralization of objects of natural and cultural heritage of Eastern Europe and Southern Siberia, based on the performance of informational function in ancient human life-support system (as instruments of navigation in space-time). Transformation of functions of sacral objects from their inception to the beginning of the third millennium, due to the development of geo-cultural space (changes in technology, socio-cultural paradigm and social and economic conditions). The stages of the evolution of navigation technologies, selected by the author on the basis of cultural layering of archaeological objects are reviewed in the article. The carried-out retrospective analysis allows to make the assumption that improvement of technologies of orientation could be a basis of emergence and development of Homo sapiens (sapientation): astronomical supervision in horizon observatory develops a system of ecological thinking; supervision over a shadow of the gnomon tool develops abstract thinking (the abstract graphic sign is genetically connected with concrete natural process). © Int. J. of GEOMATE.

Gavrilov S.P.,Herzen State Pedagogical University | Gitman D.M.,São Paulo State University
Physical Review D | Year: 2017

Nonperturbative methods have been well developed for QED with the so-called t-electric potential steps. In this case a calculation technique is based on the existence of specific exact solutions (in and out solutions) of the Dirac equation. However, there are only few cases when such solutions are known. Here, we demonstrate that for t-electric potential steps slowly varying with time there exist physically reasonable approximations that maintain the nonperturbative character of QED calculations even in the absence of the exact solutions. Defining the slowly varying regime in general terms, we can observe a universal character of vacuum effects caused by a strong electric field. In the present article, we find universal approximate representations for the total density of created pairs and vacuum mean values of the current density and energy-momentum tensor that hold true for arbitrary t-electric potential steps slowly varying with time. These representations do not require knowledge of the corresponding solutions of the Dirac equation; they have a form of simple functionals of a given slowly varying electric field. We establish relations of these representations with leading terms of the derivative expansion approximation. These results allow one to formulate some semiclassical approximations that are not restricted by the smallness of differential mean numbers of created pairs. © 2017 American Physical Society.

Goryaev M.A.,Herzen State Pedagogical University
2016 13th International Scientific-Technical Conference on Actual Problems of Electronic Instrument Engineering, APEIE 2016 - Proceedings | Year: 2016

The DC photoconductivity of powdered silicon samples was studied. Effective sensitization of photoconductivity for semiconductors with organic dyes applied to the surface of microcrystalls was found. Photoconductivity in the absorption band of the dyes in the visible part of the spectrum is increasing by more than an order of magnitude. © 2016 IEEE.

Gavrilov S.P.,Herzen State Pedagogical University | Gitman D.M.,University of Sao Paulo
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

A consistent nonperturbative approach (based on QFT) to neutral fermion creation (due to their magnetic moments) in strong inhomogeneous magnetic fields is considered. It is demonstrated that quantization in terms of neutral particles and antiparticles is possible in terms of the states with well-defined spin polarization. Such states are localizable and can form wave packets in a given asymptotic region. In this case, the problem can be technically reduced to the problem of charged-particle creation by an electric step. In particular, the relation to the Schwinger method of an effective action is established. As an example, we calculate neutral fermion creation from the vacuum by a linearly growing magnetic field. We show that the total number and the vacuum-to-vacuum transition probability of created pairs depend only on the gradient of the magnetic field, but not on its strength, and this fact does not depend on the spacetime dimension. We show that the created flux aimed in one of the directions is formed from fluxes of particles and antiparticles of equal intensity and with the same magnetic moments parallel to the external field. In such a flux, particle and antiparticle velocities that are perpendicular to the plane of the magnetic moment and flux direction are essentially depressed. The creation of neutral fermions with anomalous magnetic moments leads to a smoothing of the initial magnetic field, which in turn prevents the appearance of superstrong constant magnetic fields. Our estimations show that the vacuum instability with respect to the creation of neutrinos and even neutrons in strong magnetic fields of the magnetars and fields generated during a supernova explosion has to be taken into account in the astrophysics. In particular, it may be of significance for dark matter studies. © 2013 American Physical Society.

Gavrilov S.P.,Herzen State Pedagogical University | Gitman D.M.,São Paulo State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

Using a quantum field theory approach, we consider particle scattering and vacuum instability in the so-called L-constant electric field, which is a constant electric field confined between two capacitor plates separated by a finite distance L. We obtain and analyze special sets of stationary solutions of the Dirac and Klein-Gordon equations with the L-constant electric field. Then, we represent probabilities of particle scattering and characteristics of the vacuum instability (related to pair creation) in terms of the introduced solutions. From exact formulas, we derive asymptotic expressions for the differential mean numbers, for the total mean number of created particles, and for the vacuum-to-vacuum transition probability. Using the equivalence principle, we demonstrate that the distributions of particles created by the L-constant electric field and the gravitational field of a black hole have a similar thermal structure. © 2016 American Physical Society.

Gavrilov S.P.,Herzen State Pedagogical University | Gitman D.M.,São Paulo State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

QED with strong external backgrounds that can create particles from the vacuum is well developed for the so-called t-electric potential steps, which are time-dependent external electric fields that are switched on and off at some time instants. However, there exist many physically interesting situations where external backgrounds do not switch off at the time infinity. E.g., these are time-independent nonuniform electric fields that are concentrated in restricted space areas. The latter backgrounds represent a kind of spatial x-electric potential steps for charged particles. They can also create particles from the vacuum, the Klein paradox being closely related to this process. Approaches elaborated for treating quantum effects in the t-electric potential steps are not directly applicable to the x-electric potential steps and their generalization for x-electric potential steps was not sufficiently developed. We believe that the present work represents a consistent solution of the latter problem. We have considered a canonical quantization of the Dirac and scalar fields with x-electric potential step and have found in- and out-creation and annihilation operators that allow one to have particle interpretation of the physical system under consideration. To identify in- and out-operators we have performed a detailed mathematical and physical analysis of solutions of the relativistic wave equations with an x-electric potential step with subsequent QFT analysis of correctness of such an identification. We elaborated a nonperturbative (in the external field) technique that allows one to calculate all characteristics of zero-order processes, such, for example, scattering, reflection, and electron-positron pair creation, without radiation corrections, and also to calculate Feynman diagrams that describe all characteristics of processes with interaction between the in-, out-particles and photons. These diagrams have formally the usual form, but contain special propagators. Expressions for these propagators in terms of in- and out-solutions are presented. We apply the elaborated approach to two popular exactly solvable cases of x-electric potential steps, namely, to the Sauter potential and to the Klein step. © 2016 American Physical Society.

Vertogradov V.D.,Herzen State Pedagogical University
Gravitation and Cosmology | Year: 2015

According to Penrose’s effect, particles with negative energy can exist in the ergospheres of rotating black holes. We analyze geodesics for such particles and show that there are no circular and elliptic orbits in the ergosphere of a rotating black hole. We also show that there are geodesics which begin and terminate at the singularity and present the conditions under which such geodesics do not begin and terminate at the singularity. © 2015, Pleiades Publishing, Ltd.

Grib A.A.,Herzen State Pedagogical University | Pavlov Y.V.,Russian Academy of Sciences
Gravitation and Cosmology | Year: 2011

Scattering of particles with different masses and energy in the gravitational field of rotating black holes is considered both outside and inside the black hole. Expressions for scattering energy of particles in the center-of-mass reference frame are obtained. It is shown that the scattering energy of particles in this frame can acquire very large values not only for extremal black holes but also for nonextremal ones if one takes into account multiple scattering. Numerical estimates for the time needed for a particle to get ultrarelativistic energy are given. © 2011 Pleiades Publishing, Ltd.

Grib A.A.,Herzen State Pedagogical University
Physics-Uspekhi | Year: 2013

Current thinking on the interpretation of quantum physics is reviewed, with special detail given to the Copenhagen and Everett many-worlds interpretations. © 2013 Uspekhi Fizicheskikh Nauk, Russian Academy of Sciences.

Trifonov E.D.,Herzen State Pedagogical University
Physics-Uspekhi | Year: 2011

The well-known Bose-Einstein and Fermi-Dirac quantum distributions can be considered as stationary solutions of kinetic equations for the mean occupation numbers in an ideal gas of an arbitrary finite number of identical particles. © 2011 Uspekhi Fizicheskikh Nauk, Russian Academy of Sciences.

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