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Author Zhang, X.; Lita, A. E.; Smirnov, K.; Liu, H. L.; Zhu, D.; Verma, V. B.; Nam, S. W.; Schilling, A.
Title Strong suppression of the resistivity near the superconducting transition in narrow microbridges in external magnetic fields Type Journal Article
Year 2020 Publication Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 101 Issue 6 Pages 060508 (1 to 6)
Keywords MoSi, WSi films
Abstract (up) We have investigated a series of superconducting bridges based on homogeneous amorphous WSi and MoSi films, with bridge widths w ranging from 2 to 1000μm and film thicknesses d∼4−6 and 100 nm. Upon decreasing the bridge widths below the respective Pearl lengths, we observe in all cases distinct changes in the characteristics of the resistive transitions to superconductivity. For each of the films, the resistivity curves R(B,T) separate at a well-defined and field-dependent temperature T∗(B) with decreasing the temperature, resulting in a dramatic suppression of the resistivity and a sharpening of the transitions with decreasing bridge width w. The associated excess conductivity in all the bridges scales as 1/w, which may suggest either the presence of a highly conducting region that is dominating the electric transport, or a change in the vortex dynamics in narrow enough bridges. We argue that this effect can only be observed in materials with sufficiently weak vortex pinning.
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Series Volume Series Issue Edition
ISSN 2469-9950 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1800
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Author Smirnov, K.; Vachtomin, Y.; Divochiy, A.; Antipov, A.; Goltsman, G.
Title The limitation of noise equivalent power by background radiation for infrared superconducting single photon detectors coupled to standard single mode optical fibers Type Journal Article
Year 2015 Publication Rus. J. Radio Electron. Abbreviated Journal Rus. J. Radio Electron.
Volume Issue 5 Pages
Keywords NbN SSPD
Abstract (up) We investigated the minimum level of the dark count rates and noise equivalent power of superconducting single photon detectors coupled to standard single mode optical fibers. We found that background radiation limits the minimum level of the dark count rates. We also proposed the effective method for reducing background radiation out of the required spectral range of the detector. Measured noise equivalent power of detector reaches 8.9×10-19 W×Hz1/2 at a wavelength of 1.55 μm and quantum efficiency 35%.
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Notes 14 pages Approved no
Call Number Serial 1813
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Author Elmanov, Ilia; Elmanova, Anna; Kovalyuk, Vadim; An, Pavel; Goltsman, Gregory
Title Integrated contra-directional coupler for NV-centers photon filtering Type Conference Article
Year 2020 Publication Proc. 32-nd EMSS Abbreviated Journal Proc. 32-nd EMSS
Volume Issue Pages 354-360
Keywords NV-centers, nanodiamonds, quantum photonic integrated circuits, contra-direction coupler, Bragg gratings
Abstract (up) We modelled an integrated optical contra-directional coupler on silicon nitride platform. Performance of the filter was studied depending on different parameters, including the grating period and the height of teeth of the Bragg grating near 637 nm operation wavelength. The obtained results can be used for a design and fabrication of quantum photonic integrated circuits with on-chip single-photon NV-centers in nanodiamonds.
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ISSN 2724-0029 ISBN 978-88-85741-44-7 Medium
Area Expedition Conference 32nd European Modeling & Simulation Symposium
Notes Approved no
Call Number Serial 1839
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Author Samsonova, A. S.; Zolotov, P. I.; Baeva, E. M.; Lomakin, A. I.; Titova, N. A.; Kardakova, A. I.; Goltsman, G. N.
Title Signatures of surface magnetic disorder in niobium films Type Journal Article
Year 2021 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.
Volume 31 Issue 5 Pages 1-5
Keywords Nb films
Abstract (up) We present our studies on the evolution of the normal and superconducting properties with thickness of thin Nb films with a low level of non-magnetic disorder ( kFl≈150 for the thickest film in the set). The analysis of the superconducting behavior points to the presence of magnetic moments, hidden in the native oxide on the surface of Nb films. Using the Abrikosov-Gorkov theory, we obtain the density of surface magnetic moments of 1013 cm −2 , which is in agreement with the previously reported data for Nb films.
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1051-8223 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1792
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Author Moshkova, M. A.; Morozov, P. V.; Antipov, A. V.; Vakhtomin, Y. B.; Smirnov, K. V.
Title High-efficiency multi-element superconducting single-photon detector Type Conference Article
Year 2021 Publication Proc. SPIE Abbreviated Journal Proc. SPIE
Volume 11771 Issue Pages 2-8
Keywords PNR SSPD, large active area, detection efficiency
Abstract (up) We present the result of the creation and investigation of the multi-element superconducting single photon detectors, which can recognize the number of photons (up to six) in a short pulse of the radiation at telecommunication wavelengths range. The best receivers coupled with single-mode fiber have the system quantum efficiency of ⁓85%. The receivers have a 100 ps time resolution and a few nanoseconds dead time that allows them to operate at megahertz counting rate. Implementation of the multi-element architecture for creation of the superconducting single photon detectors with increased sensitive area allows to create the high efficiency receivers coupled with multi-mode fibers and with preserving of the all advantages of superconducting photon counters.
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Publisher SPIE Place of Publication Editor Prochazka, I.; Štefaňák, M.; Sobolewski, R.; Gábris, A.
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Area Expedition Conference Quantum Optics and Photon Counting
Notes Approved no
Call Number Serial 1795
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