Bright squeezed vacuum in a nonlinear interferometer: frequency/temporal Schmidt-mode description

Control over the spectral properties of the bright squeezed vacuum (BSV), a highly multimode non-classical macroscopic state of light that can be generated through high-gain parametric down conversion, is crucial for many applications. In particular, in several recent experiments BSV is generated in a strongly pumped SU(1,1) interferometer to achieve phase supersensitivity, perform broadband homodyne detection, or tailor the frequency spectrum of squeezed light. In this work, we present an analytical approach to the theoretical description of BSV in the frequency domain based on the Bloch-Messiah reduction and the Schmidt-mode formalism. As a special case we consider a strongly pumped SU(1,1) interferometer. We show that different moments of the radiation at its output depend on the phase, dispersion and the parametric gain in a nontrivial way, thereby providing additional insights on the capabilities of nonlinear interferometers. In particular, a dramatic change in the spectrum occurs as the parametric gain increases

Properties of bright squeezed vacuum at increasing brightness

A bright squeezed vacuum (BSV) is a nonclassical macroscopic state of light, which is generated through high-gain parametric down-conversion or four-wave mixing. Although the BSV is an important tool in quantum optics and has a lot of applications, its theoretical description is still not complete. In particular, the existing description in terms of Schmidt modes with gain-independent shapes fails to explain the spectral broadening observed in the experiment as the mean number of photons increases. Meanwhile, the semiclassical description accounting for the broadening does not allow us to decouple the intermodal photon-number correlations. In this work, we present a new generalized theoretical approach to describe the spatial properties of a multimode BSV. In the multimode case, one has to take into account the complicated interplay between all involved modes: each plane-wave mode interacts with all other modes, which complicates the problem significantly. The developed approach is based on exchanging the (k, t ) and (ω, z) representations and solving a system of integrodifferential equations. Our approach predicts correctly the dynamics of the Schmidt modes and the broadening of the angular distribution with the increase in the BSV mean photon number due to a stronger pumping. Moreover, the model correctly describes various properties of a widely used experimental configuration with two crystals and an air gap between them, namely, an SU(1,1) interferometer. In particular, it predicts the narrowing of the intensity distribution, the reduction and shift of the side lobes, and the decline in the interference visibility as the mean photon number increases due to stronger pumping. The presented experimental results confirm the validity of the new approach. The model can be easily extended to the case of the frequency spectrum, frequency Schmidt modes, and other experimental configurations

Projective filtering of a single spatial radiation eigenmode

Lossless filtering of a single coherent (Schmidt) mode from spatially multimode radiation is a problem crucial for optics in general and for quantum optics in particular. It becomes especially important in the case of nonclassical light that is fragile to optical losses. An example is bright squeezed vacuum generated via high-gain parametric down conversion or four-wave mixing. Its highly multiphoton and multimode structure offers a huge increase in the information capacity provided that each mode can be addressed separately. However, the nonclassical signature of bright squeezed vacuum, photon-number correlations, are highly susceptible to losses. Here we demonstrate lossless filtering of a single spatial Schmidt mode by projecting the spatial spectrum of bright squeezed vacuum on the eigenmode of a single-mode fiber. Moreover, we show that the first Schmidt mode can be captured by simply maximizing the fiber-coupled intensity. Importantly, the projection operation does not affect the targeted mode and leaves it usable for further applications.Comment: 10 pages, 9 figure

Heat treatment forming a dissipative metal base in wear-resistant chromium-alloyed cast iron

The maximum abrasive wear resistance is provided by a metal base from metastable retained austenite and martensite. Such a microstructure of 260Kh16M2 and 250Kh25MFT chromium cast irons with different types of Cr 7 C 3 and Cr 23 C 6 , carbides is created by high-temperature quenching with heating to temperatures of 1125-1170 °C and cooling in oil or air. Austenite is transformed to disperse martensite on the working surface as a result of the impact of abrasive particles during operation. Together with carbides, it provides a high hardening level and a high working capacity of the secondary microstructure of the cast irons. © 2018 Author(s)

THE 1st – 3rd AD ESTIMATING FINDS IN THE FOREST-STEPPE SITES OF THE TOBOL AND IRTYSH RIVERS BASIN

The article deals with artifacts found in the Iron Age kurgans over the Trans-Uralian and West Siberian forest-steppe, which might be referencing for chronology of the Sargat culture and late complexes emerging within area under study. Our emphasis is placed on the analyses of some belt and strap fittings. Meanwhile the novelty of undertaken research might be viewed less in general discussion of chronological aspects but it brings to light quite rare examples of metal belt buckles among the well-known collections. Such finds broad our knowledge on material culture of the forest-steppe population during the first centuries AD and allow the authors’ assume on origin and time of appearance of buckles with flexile tongue as items of Roman patterns. At the same time one may presume that emergence of belt fittings with such construction over the vast territory, i.e. on the south of Eastern Europe on the one side and Central Asia and Siberia on the other side could occur irrespectively in general. In chronological aspect the introduction of buckles with flexile tongue into Asiatic territory of the steppe belt could have been no earlier than during the second half of the first century AD. Based on archaeological finds from the latest complexes the highest chronological edge of the Sargat culture might be considered as not beyond the mid of the third century AD. The early third century BC marks decline and stagnation of the culture, and archaeological sites with main, blatant features dated back to the mid of the third century AD are not found in the forest-steppe eastward the Urals. All available data testify to the fact that a relatively short-term lacuna divides archaeological materials of the early Iron Age and Great Folk Movement. © 2022 Nizhnevolzhskiy Arkheologicheskiy Vestnik. All rights reserved

EFFECT OF THE COMPOSITION OF Ni(II) AND Co(II) COMPLEXES ON ELECTRODEPOSITION OF THE METALS FROM CITRATE BATHS.

The addition of amino compounds to citrate nickel plating baths facilitates plating by raising the nickel current efficiency due to a postulated formation of Ni(II) heteroligand complexes. This paper reports the electrodeposition of nickel and cobalt with the composition and nature of complexes in citrate and citrate-glycinate baths. The systems Ni(II)-H//3Cit; Ni(II)-H//3Cit-HGly and CO(II)-H//3Cit; and CO(II)-H//3Cit-HGly were studied as to complex formation and electrodeposition over a range of pH at an approximately 1:1 ratio of the original complexant concentrations to those of the coordinated entities. The plating rate was found to be a function of the composition of the complex in solution

Design and implementation of adaptive technology for teaching mathematics to school children based on integrated diagnostic approach to subject preparation and competence development

The development of school teaching  systems to enable effective adaptive communication of information requires specific pedagogical solutions to several important theoretical and methodological problems .These include 1) the discernment of basic characteristics needed to diagnose and improve the quality of subject preparation for schoolchildren, 2) clarifying the role of the teacher in the structure of adaptive learning  process, and  3) finding ways to integrate adaptive content into the framework of courses on mathematics. The purpose of our study was to determine theoretical and methodological foundations of teaching mathematics to schoolchildren taking into account their level of ability with the consequent development of appropriate adaptive content. The basic characteristics that underpin the concept of adaptive learning which contributes to both individual profiles of student ability to learn and subsequent success outcomes are: proficiency, motivation to learn and level of mathematical knowledge. The evaluation of individual profile structure of schoolchildren determines the choice of methodologies for presentation of adaptive content in ways allowing development and motivation. The system of educational process management developed in this way includes both content-methodical and procedural-technological components. This makes it possible to automatically evaluate the level of each students' mathematical training (knowledge, motivation, development) and to ensure continuous improvement. This system can also be used by secondary teachers of mathematics as a part of extracurricular activities, or as a distance learning support. In addition, the recommendations for structuring multi-level problem material can be used by mathematics teachers to self-construct adaptive sets tasks at various stages of teaching mathematics. As a result, students have the opportunity to improve their own profile of learning success, particularly by solving a chain of tasks

Humanitarization geographic education in universities

© 2015, Mediterranean Center of Social and Educational Research. All rights reserved. This article discusses the structure of science. Highlighted border integration and cross-cutting areas. Considered the most important priorities of the Russian geographical education; humanization, aimed at the development of common cultural components in the content of education in the formation of personality; humanization, expressed by an emphasis on personal factors, the social aspects of the development of society; sociologization, object of study is sociosphere - a set of geographic and socio-economic factors, with increased attention to the social aspects of development; greening, reflecting spatial processes and forms of organization of the productive forces, in order to optimize and improve production efficiency; regionalization, promoting deeper identifying the structure, function, increased understanding of the regions, the study and development of a geographical approach to the management of the region; greening, characteristic of the whole complex of geographical sciences dealing with the interaction of society and nature. Presents the contribution of prominent scientistsgeographers: V.M.Maksakovskogo - his recommendations for the Study of the greening of industry and spatial aspects; YD Demetrius, releasing a comprehensive study of the major issues of geo-ecological problems; A.M.Trofimova, MD Sharygina on the role of general geography - basic science, which considers all aspects of the development of an integrated system of "nature-economy-population" in the space-time aspect, as well as trends in long-term development of geographical education. The contribution of scientists CFI and the Institute of Ecology and Mineral Sciences of the Republic of Tatarstan in the environmental mapping

ЩОДО ПИТАННЯ УПРАВЛІННЯ ТА ОЦІНЮВАННЯ РИЗИКІВ У ДІЯЛЬНОСТІ СУДОВО-ЕКСПЕРТНИХ УСТАНОВ УКРАЇНИ

The use of international standard ISO / IEC 17025 in forensic institutions of Ukraine is an integral part of the international recognition procedure of the tests (examinations) results that they conduct. In connection with the entry of a new version of the international standard ISO / IEC 17025: 2017 and DSTU ISO / IEC 17025: 2017 into legal force, the issues of meeting new standards requirements have become increasingly relevant. The international standard provides for the use of risk-based thinking and a process approach in any field of activity, including forensic science. When conducting research, practitioners are faced with internal and external factors and various influences that lead to uncertainties in the degree of confidence regarding the examination result. Institutions that will evaluate and manage risks during their activity will have an advantage over other forensic institutions.   The purpose of the article is to review approaches to risk management and assessment, to suggest creating a single documented procedure for the risk management procedure in testing laboratories in the field of forensic science.   The article considers the concepts, basic approaches to risk management and assessment, as well as the authors present the risk management procedure developed by them in the testing laboratory of a forensic institution, which includes the stages of risk management and a risk assessment matrix.   Despite the fact that ISO / IEC 17025: 2017 does not require the development of a documented procedure for risk management, we nevertheless believe that it should be introduced for the effective operation of the testing laboratory. Development of a unified management procedure for managing and accessing risks in forensic activities will increase the results reliability of these activities.Застосування в судово-експертних установах України Міжнародного стандарту ISO/IEC 17025 є невід’ємною складовою процедури міжнарод-ного визнання результатів випробувань (досліджень), які вони проводять. Стандарт передбачає використання ризик-орієнтованого мислення та процесного підходу в будь-якій сфері діяльності, зокрема і в судово-екс-пертній. Розробляння єдиної процедури менеджменту щодо управління оцінювання ризиків у судово-експертній діяльності дасть змогу підвищи-ти достовірність результатів цієї діяльності.   Метою статті є огляд підходів до управління та оцінювання ризиків, пропозиція створення єдиної задокументованої процедури ризик-мене­ джменту випробувальних лабораторій у галузі судово-експертної діяль-ності