LOW SNR TRESHOLD IN RAPID ESTIMATORS OF COMPLEX SINUSOIDALS

A task of estimation of complex sinusoid frequency is considered. A particular but practically important case of low signal-to-noise ratio (SNR) is studied. The low SNR threshold, commonly overlooked in development of the rapid estimator of complex sinusoidals, is addressed. Signals of different length are considered and SNR is varied in wide limits. It is demonstrated that a simple interpolation with factor 2 lowers the SNR threshold by 1.5dB for the most complicated practical situations. Further interpolation does not bring any improvement. This allows proposing a compromise practical algorithm that provides accuracy close to the limit and is still very simple and fast

Financial Security of Eurasia: the Geopolitical Aspect

The article actualizes the main content and problems of implementation of the Monterrey consensus of the International conference on financing for development in the modern geopolitical and geo-economic space, the role of the International monetary Fund and its financial instruments in the Eurasian geopolitical space in this process.Purpose: to show the inconsistency of the financial policies of Western countries, challenges and threats to financial security of developing countries.Historical and comparative methods of research are used.The study revealed the selectivity of economically developed countries in approaches to financial support for developing countries, the use of financial instruments to protect the national interests of individual countries or groups to the detriment of others, the difference in approaches of the West and the East in solving problems of economic development

Quantum transport of strongly interacting photons in a one-dimensional nonlinear waveguide

We present a theoretical technique for solving the quantum transport problem of a few photons through a one-dimensional, strongly nonlinear waveguide. We specifically consider the situation where the evolution of the optical field is governed by the quantum nonlinear Schr\"odinger equation (NLSE). Although this kind of nonlinearity is quite general, we focus on a realistic implementation involving cold atoms loaded in a hollow-core optical fiber, where the atomic system provides a tunable nonlinearity that can be large even at a single-photon level. In particular, we show that when the interaction between photons is effectively repulsive, the transmission of multi-photon components of the field is suppressed. This leads to anti-bunching of the transmitted light and indicates that the system acts as a single-photon switch. On the other hand, in the case of attractive interaction, the system can exhibit either anti-bunching or bunching, which is in stark contrast to semiclassical calculations. We show that the bunching behavior is related to the resonant excitation of bound states of photons inside the system.Comment: 22 pages, 24 figure

Ultra-Slow Light and Enhanced Nonlinear Optical Effects in a Coherently Driven Hot Atomic Gas

We report the observation of small group velocities of order 90 meters per second, and large group delays of greater than 0.26 ms, in an optically dense hot rubidium gas (~360 K). Media of this kind yield strong nonlinear interactions between very weak optical fields, and very sharp spectral features. The result is in agreement with previous studies on nonlinear spectroscopy of dense coherent media

Effective organic matter stock management in agricultural practices: modeling and observation - Langfassung

RothC soil carbon dynamic model was used for simulation SOC stocks in 6 Russian long-term fertilization experiments for estimation which agricultural practices lead to soil C accumulation. For all the treatments tested above ground NPP input is sufficient for maintaining constant SOM stocks and additional C gain

ASSESSMENT OF CROP YIELDS IN MODERN AGRICULTURE ON THE BASIS OF GIS-TECHNOLOGIES - Langfasssung

The uneven distribution of natural properties- for example, soil quality, topography, microclimate - on the territory of any size determined a different degree of their suitability for growing different groups of crops. Information-analytical system of ensuring agricultural technologies was developed on the base of several GIS and models of crop yield. The system included creation of maps of potential yield (function of the natural factors) and possible (function of the real level of the field fertility) yield of various crops. These dates were received in the field experiments with fertilizers and in available modern bases of agro-chemical, landscape, climatic parameters

Von J. v. Liebig bis E. A. Mitscherlich. Die Grundlage ressourceneffizienter Pflanzenernährung - Langfassung

We share the visions of the originator of the modern soil science VV Dokuchaev and the great innovators of agrochemistry J v. Liebig, EA Mitscherlich, DN Pryanishnikov, UU Uspanov and others. Their visions were to eliminate hunger and poverty of the population by stable crop yields based on innovative site-adapted soil management and farming

Absorption resonance and large negative delay in Rb vapor with buffer gas

We observe a narrow, isolated, two-photon absorption resonance in Rb for large one-photon detuning in the presence of a buffer gas. In the absence of buffer gas, a standard Lambda configuration of two laser frequencies gives rise to electromagnetically induced transparency (EIT) for all values of one-photon detuning throughout the inhomogeneously (Doppler) broadened line. However, when a buffer gas is added and the one-photon detuning is comparable to or greater than the Doppler width, an absorption resonance appears instead of the usual EIT resonance. We also observe large negative group delay (~ -300 us for a Gaussian pulse propagating through the media with respect to a reference pulse not affected by the media), corresponding to a superluminal group velocity v_g= -c/(3.6x10^6)=-84 m/s.Comment: 4 pages, 5 figure

Intensity correlations in resonance nonlinear magneto-optical rotation

We have studied the intensity correlations between two orthogonally linearly polarized components of a laser field propagating through a resonant atomic medium. These experiments have been performed in a Rubidium atomic vapor. We observe that the correlations between the orthogonally polarized components of the laser beam are maximal in the absence of a magnetic field. The magnitude of the correlations depends on the applied magnetic field, and the magnitude first decreases and then increases with increasing magnetic field. Minimal correlations and maximal rotation angles are observed at the same magnetic fields. The width of the correlation function is directly proportional to the excited state lifetime and inversely proportional to the Rabi frequency of laser field. These results can be useful for improving optical magnetometers and for optical field or atomic spin squeezing.Comment: 8 pages, 4 figure