Electromagnetic Processes In Strongly Magnetized Plasma

The electromagnetic processes of Compton scattering and photon splitting/merging are investigated in the presence of strongly magnetized electron-positron plasma. The influence of these processes on the radiation transfer in the astrophysical environment is studied. In particular, the contribution of the processes under consideration in coefficients of the transfer equation is calculated. We show the importance of photon splitting/merging contribution and taking into account of photon dispersion and wave function renormalization in strong magnetic field and plasma.Comment: 10 pages, LaTeX, 9 figures, based on the talk presented at the XV International Seminar Quarks'2008, Sergiev Posad, Russia, 23-29 May, 2008, to appear in the Proceeding

Modeling of Quantum Key Distribution System for Secure Information Transfer

This chapter is an analysis of commercial quantum key distribution systems. Upon analysis, the general- ized structure of QKDS with phase coding of a photon state is presented. The structure includes modules that immediately participate in the task of distribution and processing of quantum states. Phases of key sequence productions are studied. Expressions that allow the estimation of physical characteristics of optoelectronic components, as well as information processing algorithms impact to rate of key sequence production, are formed. Information security infrastructure can be utilized, for instance, to formulate requirements to maximize tolerable error level in quantum channel with a given rate of key sequence production

The Compton effect in a strongly magnetized plasma

The process of Compton scattering $\gamma e^{\pm} \to \gamma e^{\pm}$ in a strongly magnetized medium of arbitrary temperature and zeroth chemical potential was considered. The analytical expressions for the partial cross section in the small concentration limit of the electron-positron plasma are obtained. The numerical estimations for the partial probabilities of this process are presented by taking into account the photon dispersion in a strong magnetic field and charge-symmetric plasma of arbitrary temperature. The comparision of the scattering probability with photon splitting in a plasma was investigated. The astrophysical applications of the obtaining results are considered.Comment: 9 pages, LaTeX, 5 figures, based on the talk presented by D.A. Rumyantsev at the XIV International Seminar Quarks'2006, St.-Petersburg, Repino, Russia, May 19-25, 2006, to appear in the Proceeding

Comment on "Structure of the two-neutrino double-\beta\ decay matrix elements within perturbation theory" by Du\v{s}an \v{S}tef\'anik, Fedor \v{S}imkovic, Amand Faessler, arXiv:1506.00835 [nucl-th], Phys.Rev.C91 (2015) 6, 064311

We comment on a priority claim given by the authors of Phys.Rev.C91 (2015) 6, 064311

Generalized two-point tree-level amplitude jf→j ′f ′jf \to j^{\, \prime} f^{\, \prime} in a magnetized medium

The tree-level two-point amplitudes for the transitions $jf \to j^{\, \prime} f^{\, \prime}$, where $f$ is a fermion and $j$ is a generalized current, in a constant uniform magnetic field of an arbitrary strength and in charged fermion plasma, for the $jff$ interaction vertices of the scalar, pseudoscalar, vector and axial-vector types have been calculated. The generalized current $j$ could mean the field operator of a boson, or a current consisting of fermions, e.g. the neutrino current. The particular cases of a very strong magnetic field, and of the coherent scattering off the real fermions without change of their states (the "forward" scattering) have been analysed. The contribution of the neutrino photoproduction process, $\gamma e\to e \nu \bar \nu$, to the neutrino emissivity has been calculated with taking account of a possible resonance on the virtual electron.Comment: 23 pages, LaTeX, 1 EPS figure, submitted to Int. J. Mod. Phys. A. arXiv admin note: substantial text overlap with arXiv:1312.571

Photon splitting and Compton scattering in strongly magnetized hot plasma

The process of photon splitting is investigated in the presence of strongly magnetized electron-positron plasma. The amplitude of the process is calculated in general case of plasma with nonzero chemical potential and temperature. The polarization selection rules and corresponding partial amplitudes for allowed splitting channels are obtained in the case of charge-symmetric plasma. It is found that the new splitting channel forbidden in magnetized vacuum becomes allowed. The absorption rates of the photon splitting are calculated with taking into account of the photon dispersion and wave function renormalization. In addition, the comparison of photon splitting and Compton scattering process is made. The influence of the reactions under consideration on the radiation transfer in the framework of magnetar model of SGR burst is discussed.Comment: 17 pages, 17 figures. v2: minor changes, typos corrected, to be published in Phys.Rev.

Generalized two-point tree-level amplitude jf→j ′f ′jf \to j^{\, \prime} f^{\, \prime} in a magnetized medium (extended version)

The tree-level two-point amplitudes for the transitions $jf \to j^{\, \prime} f^{\, \prime}$, where $f$ is a fermion and $j$ is a generalized current, in a constant uniform magnetic field of an arbitrary strength and in charged fermion plasma, for the $jf$ interaction vertices of the scalar, pseudoscalar, vector and axial-vector types have been investigated. The particular cases of a very strong magnetic field, and of the coherent scattering off the real fermions without change of their states (the "forward" scattering) have been analysed.Comment: 37 pages, 1 eps figure, extended version of the paper submitted to Physical Review D; version 2: some misprints are corrected in Eqs. (29) - (72) and corresponding changes are made in Sec. 3 and 4; the gamma_5 matrix definition is specified, and general signs are changed correspondingly in the amplitudes PS, SP, AS, SA, PV, V

The Discrete Noise of Magnons

Magnonics is a rapidly developing subfield of spintronics, which deals with devices and circuits that utilize spin currents carried by magnons - quanta of spin waves. Magnon current, i.e. spin waves, can be used for information processing, sensing, and other applications. A possibility of using the amplitude and phase of magnons for sending signals via electrical insulators creates conditions for avoiding Ohmic losses, and achieving ultra-low power dissipation. Most of the envisioned magnonic logic devices are based on spin wave interference, where the minimum energy per operation is limited by the noise level. The sensitivity and selectivity of magnonic sensors is also limited by the low frequency noise. However, the fundamental question "do magnons make noise?" has not been answered yet. It is not known how noisy magnonic devices are compared to their electronic counterparts. Here we show that the low-frequency noise of magnonic devices is dominated by the random telegraph signal noise rather than 1/f noise - a striking contrast to electronic devices (f is a frequency). We found that the noise level of surface magnons depends strongly on the power level, increasing sharply at the on-set of nonlinear dissipation. The presence of the random telegraph signal noise indicates that the current fluctuations involve random discrete macro events. We anticipate that our results will help in developing the next generation of magnonic devices for information processing and sensing.Comment: 18 pages; 3 figure

Neutrino photoproduction on electron in dense magnetized medium

The effect of a strongly magnetized cold plasma on the Compton-like photoproduction of a neutrino-antineutrino pair on an electron, $\gamma e \to e \nu \bar \nu$, has been considered. The contribution of this process to the neutrino emissivity in both the non-resonance and the resonance cases has been calculated with taking account of the photon dispersion properties in medium. Our results show that the neutrino emissivity owing to the $\gamma e \to e \nu \bar \nu$ reaction is significantly modified as compared to the previously reported data.Comment: 9 pages, LaTeX, 3 EPS figures, based on the talk presented by D.A. Rumyantsev at the XVIII International Seminar Quarks'2014, Suzdal, Russia, June 2-8, 201

High-Temperature Performance of MoS2 Thin-Film Transistors: DC and Pulse Current-Voltage Characteristics

The measurements of the high - temperature current - voltage characteristics of MoS2 thin - film transistors show that the devices remain functional to temperatures of at least as high as 500 K. The temperature increase results in decreased threshold voltage and mobility. The comparison of the DC and pulse measurements shows that the DC sub - linear and super - linear output characteristics of MoS2 thin - films devices result from the Joule heating and the interplay of the threshold voltage and mobility temperature dependences. At temperatures above 450 K, an intriguing phenomenon of the "memory step" - a kink in the drain current - occurs at zero gate voltage irrespective of the threshold voltage value. The memory step effect was attributed to the slow relaxation processes in thin films similar to those in graphene and electron glasses. The obtained results suggest new applications for MoS2 thin - film transistors in extreme - temperature electronics and sensors.Comment: 22 pages, 8 figure