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Author Arutyunov, K. Y.; Ramos-Álvarez, A.; Semenov, A. V.; Korneeva, Y. P.; An, P. P.; Korneev, A. A.; Murphy, A.; Bezryadin, A.; Gol’tsman, G. N.
Title Quasi-1-dimensional superconductivity in highly disordered NbN nanowires Type Miscellaneous
Year 2016 Publication arXiv Abbreviated Journal
Volume Issue Pages
Keywords (up) narrow NbN nanowires, BCS
Abstract The topic of superconductivity in strongly disordered materials has attracted a significant attention. In particular vivid debates are related to the subject of intrinsic spatial inhomogeneity responsible for non-BCS relation between the superconducting gap and the pairing potential. Here we report experimental study of electron transport properties of narrow NbN nanowires with effective cross sections of the order of the debated inhomogeneity scales. We find that conventional models based on phase slip concept provide reasonable fits for the shape of the R(T) transition curve. Temperature dependence of the critical current follows the text-book Ginzburg-Landau prediction for quasi-one-dimensional superconducting channel Ic~(1-T/Tc)^3/2. Hence, one may conclude that the intrinsic electronic inhomogeneity either does not exist in our structures, or, if exist, does not affect their resistive state properties.
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Notes Duplicated as 1332 Approved no
Call Number Serial 1338
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Author Arutyunov, K. Y.; Ramos-Alvarez, A.; Semenov, A. V.; Korneeva, Y. P.; An, P. P.; Korneev, A. A.; Murphy, A.; Bezryadin, A.; Gol'tsman, G. N.
Title Superconductivity in highly disordered NbN nanowires Type Journal Article
Year 2016 Publication Nanotechnol. Abbreviated Journal Nanotechnol.
Volume 27 Issue 47 Pages 47lt02 (1 to 8)
Keywords (up) NbN nanowires
Abstract The topic of superconductivity in strongly disordered materials has attracted significant attention. These materials appear to be rather promising for fabrication of various nanoscale devices such as bolometers and transition edge sensors of electromagnetic radiation. The vividly debated subject of intrinsic spatial inhomogeneity responsible for the non-Bardeen-Cooper-Schrieffer relation between the superconducting gap and the pairing potential is crucial both for understanding the fundamental issues of superconductivity in highly disordered superconductors, and for the operation of corresponding nanoelectronic devices. Here we report an experimental study of the electron transport properties of narrow NbN nanowires with effective cross sections of the order of the debated inhomogeneity scales. The temperature dependence of the critical current follows the textbook Ginzburg-Landau prediction for the quasi-one-dimensional superconducting channel I c approximately (1-T/T c)(3/2). We find that conventional models based on the the phase slip mechanism provide reasonable fits for the shape of R(T) transitions. Better agreement with R(T) data can be achieved assuming the existence of short 'weak links' with slightly reduced local critical temperature T c. Hence, one may conclude that an 'exotic' intrinsic electronic inhomogeneity either does not exist in our structures, or, if it does exist, it does not affect their resistive state properties, or does not provide any specific impact distinguishable from conventional weak links.
Address National Research University Higher School of Economics, Moscow Institute of Electronics and Mathematics,109028, Moscow, Russia. P L Kapitza Institute for Physical Problems RAS, Moscow, 119334, Russia
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Language English Summary Language Original Title
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ISSN 0957-4484 ISBN Medium
Area Expedition Conference
Notes PMID:27782000 Approved no
Call Number Serial 1332
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Author Golikov, A.; Kovalyuk, V.; An, P.; Zubkova, E.; Ferrari, S.; Pernice, W.; Korneev, A.; Goltsman, G.
Title Silicon nitride nanophotonic circuit for on-chip spontaneous four-wave mixing Type Conference Article
Year 2018 Publication J. Phys.: Conf. Ser. Abbreviated Journal J. Phys.: Conf. Ser.
Volume 1124 Issue Pages 051051
Keywords (up) O-ring resonator
Abstract Here we present an integrated nanophotonic circuit for on-chip spontaneous four-wave mixing. The fabricated device includes an O-ring resonator, a Bragg noch-filter as well as a nine-channel arrayed waveguide gratings (AWG) operated in the C-band wavelength range (1550 nm). The measured optical losses of the device (-6.8 dB) as well as a high Q-factor (> 1.2×105) shows a good potential for realizing the spontaneous four-wave mixing on the silicon nitride chip.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1742-6588 ISBN Medium
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Notes Approved no
Call Number Serial 1193
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Author Prokhodtsov, A.; An, P.; Kovalyuk, V.; Zubkova, E.; Golikov, A.; Korneev, A.; Ferrari, S.; Pernice, W.; Goltsman, G.
Title Optimization of on-chip photonic delay lines for telecom wavelengths Type Conference Article
Year 2018 Publication J. Phys.: Conf. Ser. Abbreviated Journal J. Phys.: Conf. Ser.
Volume 1124 Issue Pages 051052
Keywords (up) optical delay lines
Abstract In this work, we experimentally studied optical delay lines on silicon nitride platform for telecomm wavelength (1550 nm). We modeled the group delay time and fabricated spiral optical delay lines with different waveguide widths and radii as well as measured their transmission. For the half etched rib waveguides we achieved the losses in the range of 3 dB/cm.
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ISSN 1742-6588 ISBN Medium
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Notes Approved no
Call Number Serial 1196
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Author Kovaluyk, V.; Lazarenko, P.; Kozyukhin, S.; An, P.; Prokhodtsov, A.; Goltsman, G.; Sherchenkov, A.
Title Influence of the phase state of Ge2Sb2Te5 thin cover on the parameters of the optical waveguide structures Type Abstract
Year 2019 Publication Proc. Amorphous and Nanostructured Chalcogenides Abbreviated Journal Proc. Amorphous and Nanostructured Chalcogenides
Volume Issue Pages 47-48
Keywords (up) optical waveguides
Abstract The fast switching time of Ge-Sb-Te thin films between amorphous and crystalline states initiated by laser beam as well as significant change of their optical properties and the preservation of metastable states for tens of years open wide perspectives for the application of these materials to fully optical devices [1], including high-speed optical memory [2]. Here we study optical properties of the Ge2Sb2Te5 (GST225) thin films integrated with on-chip silicon nitride O-ring resonator. The rib waveguide of the resonator was formed the first stage of e-beam lithography and subsequent reactive-ion etching. We used the second stage of e-beam lithography combining with lift-off method for the formation of GST225 active region on the resonator ring surface. The amorphous GST225 thin films were prepared by magnetron sputtering, and were capped by thin silicon oxide on their tops. The length of the GST225 active region varied from 0.1 to 20 μ m. Crystallization of amorphous thin films was carried out at the temperature of 400 °C for 30 minutes. Auger electron spectroscopy and transmission electron microscopy were used for studying composition and structure of investigated GST225thin films, respectively. It was observed that crystallization of amorphous GST225 film lead to a decrease of the optical power, transmitted through the waveguide. Comparison of the optical transmittance of O-ring resonators before and after the GST225 deposition allowed to identify the change in the Q-factor and the wavelength peak shift. This can be explained by the differences of the complex refractive indexes of GST225 thin films in the amorphous and crystalline states. From the measurement data, the GST225 effective refractive index was extracted depending on the ring waveguide width of the resonator for a telecommunication wavelength of 1550 nm.
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Publisher Technical University of Moldova Place of Publication Editor
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Notes Poster Approved no
Call Number Serial 1281
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