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

Kinetics of grain refinemet in metallic materials during large strain deformation

The development of ultrafine grained microstructures in austenitic stainless steel and pure titanium subjected to large strain deformation was comparatively studied. The change in the volume fractions of newly developed ultrafine grains was used to quantify the progress in grain refinement during plastic deformatio

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

An effect of anti-stress feed additives on broiler productivity and meat quality

The paper presents the study on an impact of feed additives Peak anti-stress and SPAO (SPAO-complex) with different lithium content on meat productivity and meat quality of broiler chickens. The feed additives exert a pronounced metabolic effect, have adaptogen properties and allow forming a mechanism that facilitates compensation of the expenditure of the body, which significantly increases upon stress development. It was established that the average daily gain of the broiler chickens increased by 1.8% and 4.3% on the background of using SPAO-complex and Peak anti-stress, respectively, compared to the broiler chickens that did not receive the feed additives in the daily diet. It was shown that addition of feed additives with lithium into a diet led to an improvement of the indices of broiler meat productivity and meat quality: a level of yield of the carcasses of the 1st category increased up to 56.2–79.1%, high organoleptic indices of meat were ensured, the protein content in white and red chicken meat increased and functional-technological properties of minced meat improved. The use of feed additives ensured profitability of industrial poultry production; the highest indices of profitability were established upon introduction of the feed additive Peak anti-stress into a diet — up to 8.67 rubles per each ruble of expenses. The obtained results of the study should be taken into consideration in the technological processes when raising broiler chickens