Photon-Pair Generation from Chip-Scale Cs Atomic Vapor Cell

The realization of a narrowband photonic quantum source based on a chip-scale atomic device is considered essential in the practical development of photonic quantum information science and technology. In this study, we present the first step toward the development of a photon-pair source based on a microfabricated chip-scale Cs atomic vapor cell. Time-correlated photon pairs from the millimeter-scale Cs vapor cell are emitted via the spontaneous four-wave mixing process of the cascade-type 6S1/2–6P3/2–8S1/2 transition of 133Cs. The maximum normalized cross-correlation value between the signal and idler photons is measured as 622(8) under a weak pump power of 10 mW. Our photon source violates the Cauchy–Schwartz inequality by a factor of >105. We believe that our approach has very important applications in the context of realizing practical scalable quantum networks based on atom–photon interactions.

ACTIVITY TO PREVENT EMERGENCY SITUATIONS OF CASCADE TYPE OF SPREADING RELATED TO SOIL LANDSLIDE

Landfills for solid waste with liquidation energy-intensive technological equipment, due to emergencies of the cascade type of distribution associated with the landslide of landfills, pose a man-made environmental hazard. Experimental studies to determine the effect of humidity, density, temperature of landfill soils on the stability of slopes on landslides have shown that with increasing humidity and temperature, the resistance of the array to displacement decreases. The lower the density, the greater the ability to penetrate and saturate with moisture, which creates additional shear load. According to the results of experimental research, a method of prevention of cascade-type emergencies related to landfill landslides at the landfill with liquid energy-intensive technological equipment has been developed to prevent the consequences of danger from escalating from site to higher levels of distribution. The method consists of measures "before" and "after" the fact of moving the landslide.

Performance Evaluation of Modified Low-Temperature Cascade (MLTC) Type Refrigeration System

An experimental investigation was carried out to study the performance evaluation of Modified Low-Temperature Cascade (MLTC) system, based on two-stage cascade type refrigeration system using the combination of R404A/R23 refrigerants. This system was developed using chilled water (CHW) in the condenser of high-temperature circuit (HTC) and pre-cooler (PC) in the low-temperature circuit (LTC). Isentropic compression efficiency is computed in this work and used here as an important parameter. Performance of MLTC system was compared with or without the introduction of PC into LTC. System’s coefficient of performance (COP) has also been compared with using CHW, cooling tower water (CTW), normal water (NW) into the HTC condenser. It has also been shown that COPs of the system are significantly affected by slight variation in the LTC and HTC evaporating temperatures. Presented parameters and comparisons are likely to help in developing a low-temperature (LT) refrigeration system with higher efficiency for industrial and other applications.

Spectral–temporal biphoton waveform of photon pairs from cascade-type warm atoms

We investigate the spectral–temporal biphoton waveforms of the photon pairs emitted from cascade-type two-photon-coherent warm 87Rb atoms via the spontaneous four-wave mixing process in the 5S1/2–5P3/2–5D5/2 transition, under the condition of the different detuning frequencies (symmetric detuning conditions of ± 1 GHz) of the pump and coupling lasers relative to the 5P3/2 state. In both detuning cases corresponding to ± 1 GHz, the biphoton temporal waveforms and biphoton spectral waveforms of the photon pairs are measured by means of time-resolved coincidence photon counting and stimulated measurements, respectively. Although photon-pairs were generated using opposite detunings, we confirm that the spectral–temporal biphoton waveforms of the photon pairs are very similar. Furthermore, we observe Hong–Ou–Mandel interference with 82% visibility with the two independent heralded single photons.

DEVELOPMENT OF THE CONTROL ALGORITHM OF THE METHODOLOGY OF EMERGENCY PREVENTION ON LANDFILL WITH LIQUIDATION ENERGY-INTENSIVE TECHNOLOGICAL EQUIPMENT

Landfills taking into account current trends in the placement of innovative liquidation technologies on their territory with a variety of energy-intensive technological equipment pose an additional technogenic danger. This requires a set of measures to prevent emergencies of the cascade type of distribution, due to the shift of the slope of the waste masses with the subsequent explosion of biogas. Analysis of existing approaches to modeling the conditions of solid waste landfills proves the lack of comprehensive studies to assess the effectiveness of solid waste landfills in the case of the introduction of additional technological energy-intensive technological equipment. In the course of the work the author considers the physical conditions of emergency prevention at the landfill in the conditions of a separate task of involving liquidation energy-intensive technological equipment. Depending on the location of the specified equipment in relation to the landfill, emergencies of cascade type may occur due to the shift of waste masses with the subsequent explosion of biogas. In the course of the work the author developed a control algorithm for the implementation of a mathematical model of cascade type emergency prevention at solid waste landfills with liquidation energy-intensive technological equipment due to loss of stability of the slope of the waste array to landslide followed by biogas explosion. The control algorithm consists of 18 analytical blocks, which are located on two levels and are interconnected by direct and feedback. In order to further practical application of the control algorithm, it is necessary to develop an appropriate methodology, the implementation of which should effectively counteract the emergency situation with priority consequences, such as the number of victims, the number of deaths, the number of people with impaired living conditions. Keywords: landfill, emergency prevention, liquidation energy-intensive technological equipment, explosion, landslide