Surface acoustic wave modulation of single photon emission from GaN/InGaN nanowire quantum dots

On-chip quantum information processing requires controllable quantum light sources that can be operated on-demand at high-speeds and with the possibility of in-situ control of the photon emission wavelength and its optical polarization properties. Here, we report on the dynamic control of the optical emission from core-shell GaN/InGaN nanowire (NW) heterostructures using radio frequency surface acoustic waves (SAWs). The SAWs are excited on the surface of a piezoelectric lithium niobate crystal equipped with a SAW delay line onto which the NWs were mechanically transferred. Luminescent quantum dot (QD)-like exciton localization centers induced by compositional fluctuations within the InGaN nanoshell were identified using stroboscopic micro-photoluminescence (micro-PL) spectroscopy. They exhibit narrow and almost fully linearly polarized emission lines in the micro-PL spectra and a pronounced anti-bunching signature of single photon emission in the photon correlation experiments. When the nanowire is perturbed by the propagating SAW, the embedded QD is periodically strained and its excitonic transitions are modulated by the acousto-mechanical coupling, giving rise to a spectral fine-tuning within a ~1.5 meV bandwidth at the acoustic frequency of ~330 MHz. This outcome can be further combined with spectral detection filtering for temporal control of the emitted photons. The effect of the SAW piezoelectric field on the QD charge population and on the optical polarization degree is also observed. The advantage of the acousto-optoelectric over other control schemes is that it allows in-situ manipulation of the optical emission properties over a wide frequency range (up to GHz frequencies).Comment: arXiv admin note: text overlap with arXiv:1902.0791

Preparation of pine flotation oil by hydration with α-pinene

The hydration of α-pinene of gum turpentine and separately pinene fractions in the organic acids media for the purpose of obtaining terpene alcohols, which are widely used as flotation reagent for mineral processing in mining production were studied. The best results are obtained among the organic acids when 70% formic acid is used. The α-pinene hydration process in the acid imedium is exothermic, and it is necessary to maintain a constant temperature of 65 °C to reduce the rate of side reactions. The main component of turpentine, resulting in the formation of α-terpineol is α-pinene; 3-carene, terpinolene, and limonene contents do not practically change in the reaction mixture, which testify their stability in 70% formic acid media. The maximum content of terpene alcohols (60,1%) was obtained when using α-pinene fraction at a ratio of α-pinene and 70% formic acid 1.0 : 1.1 for 3 hours. Increase of the duration of hydration reaction leads to the decrease in the content of terpineol in the reactio n mixture due to the secondary isomerization processes

Hierarchical Model of Assessing and Selecting Experts

Revealing experts' competences is a multi-objective issue. Authors of the paper deal with competence assessing methods of experts seen as objects, and criteria of qualities. An analytic hierarchy process of assessing and ranking experts is offered, which is based on paired comparison matrices and scores, quality parameters are taken into account as well. Calculation and assessment of experts is given as an example

Fumaric acid amides in technologies of paper and cardboard

Fumaric acid polyamids were synthesized by interaction of fumaric acid with polyamines (diethylenetriamine, triethylenetetramine) by equilibrium polycondensation in the melt. The obtained products are promising as hardening additives in the technology of paper and cardboard. This article studies the type and rate effects of fumaric acid polyamides on some paper strength properties (breaking length, breaking force in dry and wet states). It is shown that the greatest effect of the paper hardening is achieved by using the additive, which is a product of polycondensation of fumaric acid and diethylenetriamine

Photoionization of Xe 3d electrons in molecule Xe@C60: interplay of intra-doublet and confinement resonances

We demonstrate rather interesting manifestations of co-existence of resonance features in characteristics of the photoionization of 3d-electrons in Xe@C60. It is shown that the reflection of photoelectrons produced by the 3d Xe photoionization affects greatly partial photoionization cross-sections of and levels and respective angular anisotropy parameters, both dipole and non-dipole adding to all of them additional maximums and minimums. The calculations are performed treating the 3/2 and 5/2 electrons as electrons of different kinds with their spins "up" and "down". The effect of C60 shell is accounted for in the frame of the "orange" skin potential model.Comment: 13 pages, 12 figure