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Author Beck, M.; Rousseau, I.; Klammer, M.; Leiderer, P.; Mittendorff, M.; Winnerl, S.; Helm, M.; Gol'tsman, G.N.; Demsar, J.
Title Transient increase of the energy gap of superconducting NbN thin films excited by resonant narrow-band terahertz pulses Type Journal Article
Year 2013 Publication Phys. Rev. Lett. Abbreviated Journal Phys. Rev. Lett.
Volume 110 Issue 26 Pages 267003 (1 to 5)
Keywords NbN thin films, energy gap
Abstract Observations of radiation-enhanced superconductivity have thus far been limited to a few type-I superconductors (Al, Sn) excited at frequencies between the inelastic scattering rate and the superconducting gap frequency 2Delta/h. Utilizing intense, narrow-band, picosecond, terahertz pulses, tuned to just below and above 2Delta/h of a BCS superconductor NbN, we demonstrate that the superconducting gap can be transiently increased also in a type-II dirty-limit superconductor. The effect is particularly pronounced at higher temperatures and is attributed to radiation induced nonthermal electron distribution persisting on a 100 ps time scale.
Address Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457, Germany
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ISSN 0031-9007 ISBN Medium
Area Expedition Conference
Notes PMID:23848912 Approved no
Call Number Serial 1370
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Author Pentin, I. V.; Smirnov, A. V.; Ryabchun, S. A.; Ozhegov, R. V.; Gol’tsman, G. N.; Vaks, V. L.; Pripolzin, S. I.; Pavel’ev, D. G.; Koshurinov, Y. I.; Ivanov, A. S.
Title Semiconducting superlattice as a solid-state terahertz local oscillator for NbN hot-electron bolometer mixers Type Journal Article
Year 2012 Publication Tech. Phys. Abbreviated Journal Tech. Phys.
Volume 57 Issue 7 Pages 971-974
Keywords semiconducting superlattice frequency multiplier, NbN HEB mixers
Abstract We present the results of our studies of the semiconducting superlattice (SSL) frequency multiplier and its application as part of the solid state local oscillator (LO) in the terahertz heterodyne receiver based on a NbN hot-electron bolometer (HEB) mixer. We show that the SSL output power level increases as the ambient temperature is lowered to 4.2 K, the standard HEB operation temperature.
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ISSN 1063-7842 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1378
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Author Gurovich, B. A.; Tarkhov, M. A.; Prikhod'ko, K. E.; Kuleshova, E. A.; Komarov, D. A.; Stolyarov, V. L.; Olshanskii, E. D.; Goncharov, B. V.; Goncharova, D. A.; Kutuzov, L. V.; Domantovskii, A. G.
Title Controlled modification of superconducting properties of NbN ultrathin films under composite ion beam irradiation Type Journal Article
Year 2014 Publication Nanotechnologies in Russia Abbreviated Journal Nanotechnologies in Russia
Volume 9 Issue 7 Pages 386-390
Keywords superconducting NbN films composite ion beam irradiation protoning
Abstract In this work, the results of studying the microstructure and superconducting properties of ultrathin films on the basis of NbN in the initial state and after modification by being subjecting to composite ion beam irradiation with the energy ~1–3) keV are presented. HRTEM analysis showed that the initial films on the sapphire substrate in orientation “c-cut” are characterized by a grain size essentially exceeding the film thickness, while on the other substrates the size of grains corresponds to the thickness of film. Using XPS analysis, it was shown that in the initial films the atomic ratio of Nb and N is 0.51/0.49, respectively, the percentage of oxygen being lower than 5%. For ultrathin films 5 nm in thickness, the critical temperature of transit to superconducting state (T c) is found to be ~3.6 K and the density of critical current is jc ~8MA/cm2. In the work it is experimentally determined that the irradiation of NbN films by composite ion beams leads to the controlled modification of its superconducting properties due to the process of selective substitution of nitrogen atoms on the oxygen atoms.
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Notes Approved no
Call Number Serial 1000
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Author Korneev, A.; Korneeva, Y.; Florya, I.; Voronov, B.; Goltsman, G.
Title NbN nanowire superconducting single-photon detector for mid-infrared Type Journal Article
Year 2012 Publication Phys. Procedia Abbreviated Journal Phys. Procedia
Volume 36 Issue Pages 72-76
Keywords NbN SSPD, SNSPD
Abstract Superconducting single-photon detectors (SSPD) is typically 100 nm-wide supercondiucting strip in a shape of meander made of 4-nm-thick film. To reduce response time and increase voltage response a parallel connection of the strips was proposed. Recently we demonstrated that reduction of the strip width improves the quantum effciency of such a detector at wavelengths longer than 1.5 μm. Being encourage by this progress in quantum effciency we improved the fabrication process and made parallel-wire SSPD with 40-nm-wide strips covering total area of 10 μm x 10 μm. In this paper we present the results of the characterization of such a parallel-wire SSPD at 10.6 μm wavelength and demonstrate linear dependence of the count rate on the light power as it should be in case of single-photon response.
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ISSN 1875-3892 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1382
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Author Korneev, A.; Divochiy, A.; Marsili, F.; Bitauld, D.; Fiore, A.; Seleznev, V.; Kaurova, N.; Tarkhov, M.; Minaeva, O.; Chulkova, G.; Smirnov, K.; Gaggero, A.; Leoni, R.; Mattioli, F.; Lagoudakis, K.; Benkhaoul, M.; Levy, F.; Goltsman, G.
Title Superconducting photon number resolving counter for near infrared applications Type Conference Article
Year 2008 Publication Proc. SPIE Abbreviated Journal Proc. SPIE
Volume 7138 Issue Pages 713828 (1 to 5)
Keywords PNR SSPD; SNSPD; Nanowire superconducting single-photon detector, ultrathin NbN film, infrared
Abstract We present a novel concept of photon number resolving detector based on 120-nm-wide superconducting stripes made of 4-nm-thick NbN film and connected in parallel (PNR-SSPD). The detector consisting of 5 strips demonstrate a capability to resolve up to 4 photons absorbed simultaneously with the single-photon quantum efficiency of 2.5% and negligibly low dark count rate.
Address
Corporate Author Thesis
Publisher Spie Place of Publication Editor Tománek, P.; Senderáková, D.; Hrabovský, M.
Language Summary Language Original Title
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ISSN ISBN Medium
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Notes Approved no
Call Number 10.1117/12.818079 Serial 1241
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