Slow Electron-Phonon Cooling in Superconducting Diamond Films
We have measured the electron-phonon energy-relaxation time, τeph, in superconducting boron-doped diamond films grown on silicon substrate by chemical vapor deposition. The observed electron-phonon cooling times vary from 160 ns at 2.70 K to 410 ns at 1.8 K following a T -2-dependence. The data are consistent with the values of τeph previously reported for single-crystal boron-doped diamond films epitaxially grown on diamond substrate. Such a noticeable slow electron-phonon relaxation in boron-doped diamond, in combination with a high normal-state resistivity, confirms a potential of superconducting diamond for ultrasensitive superconducting bolometers.
We demonstrate that a temperature gradient can strongly stimulate the thermoelectric signal, as well as dc Josephson current, in multiterminal superconducting hybrid nanostructures. At temperatures T sufficiently exceeding the Thouless energy of our device, both the supercurrent and the thermoinduced voltage are dominated by the contribution from nonequilibrium low-energy quasiparticles and are predicted to decay slowly (algebraically rather than exponentially) with increasing T . We also predict a nontrivial current-phase relation and a transition to a π-junction state controlled by both the temperature gradient and the system topology. All these features are simultaneously observable in the same experiment.
The photon count rate (PCR) ofsuperconducting single-photon detectors made ofMoxSi1-x films shaped as a 2-μm-wide strip and a 115-nm-wide meander strip line is studied experimentally as a function of the dc biasing current at different values of the perpendicular magnetic field. For the wide strip, a crossover current Icross is observed, below which the PCR increases with an increasing magnetic field and above which it decreases. This behavior contrasts with the narrow MoxSi1-x meander, for which no crossover current is observed, thus suggesting different photon-detection mechanisms in the wide and narrow strips. Namely, we argue that in the wide strip the absorbed photon destroys superconductivity locally via the vortex-antivortex mechanism for the emergence of resistance, while in the narrow meander superconductivity is destroyed across the whole strip line, forming a hot belt. Accordingly, the different photon-detection mechanisms associated with vortices and the hot belt determine the qualitative difference in the dependence of the PCR on the magnetic field
Conventional superconductivity in bulk objects is characterized by three phenomenological features: zero resistivity, perfect diamagnetism ( Meissner effect) and energy gap in the excitation spectrum. In this paper we demonstrate that these attributes of superconductivity do not apply to ultra-small objects governed by the essentially nanoscale phenomenon which is quantum fluctuations. The observation results in fundamental limitations of utilization of superconducting elements in nanoelectronic circuits. However, together with this rather pessimistic conclusion, the indicated size phenomena lead to a new class of nanoscale devices and applications.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.
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.