Comparison of hot spot formation in NbC and NbN single photon detectors
We report an experimental investigation of the hot spot evolution in superconducting single photons detectors (SSPDs) made of disordered superconducting materials with different diffusivity and energy down-conversion time: 33-nmthickNbN and 23-nm-thick NbC films. We have demonstrated that in NbC film only 405 nm photons produce sufficiently largehot-spot to trigger a single-photon response. The dependence of detection efficiency on bias current for 405-nm photons in NbC is similar to that for 3400-nm photons in NbN. In NbC large diffusivity and down-conversion time result in 1D critical current suppression profile compared to usual 2D profile in NbN.
The contribution of electron–phonon scattering to conductivity of a quantum cylinder in a lon-gitudinal magnetic field has been studied. It has been shown that the conductivity of the nanotube undergoes Aharonov–Bohm oscillations with variations in the magnetic flux through the nanotube cross section. The formulas describing the temperature dependence of the resistance of the nanostructure both in the case of an isotropic phonon spectrum and with allowance for the effects of phonon confinement have been obtained in the analytical form.
In quiet low-latitude Earth's ionosphere, a rather developed current system that is responsible for the Sq magnetic-field variations is formed in quiet sunny days under the action of tidal streams. The density of the corresponding currents is maximal at the equatorial latitudes in the midday hours, where the so-called equatorial current jet is formed. In this work, we discuss the nature of the equatorial current jet. The original part of this paper is dedicated to the study of the value of its response to external effects. First of all, it is related to estimating the possibility of using the equatorial current jet for generating the low-frequency electromagnetic signals during periodic heating of the ionosphere by the heating-facility radiation. The equatorial current jet can also produce electrodynamic response to the natural atmospheric processes, e.g., an acoustic-gravitational wave.
The article considers the questions assessing the reliability of mechanical components used in the electronic equipment in the early stages of design. The calculations of failure rates springs shock absorbers according to various methods. It is shown that the use of models failure rates of mechanical elements, taking into account the peculiarities of their structural and technological performance, not only allows us to solve the problem of calculating, but also to ensure the required level of reliability and mechanical components, and containing electronic equipment.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.