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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 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 (up) Duplicated as 1332 Approved no
Call Number Serial 1338
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Author Hübers, Heinz-Wilhelm; Semenov, A.; Richter, H.; Smirnov, K.; Gol'tsman, G.; Voronov, B.
Title Phonon cooled far-infrared hot electron bolometer mixer Type Abstract
Year 2002 Publication NASA/ADS Abbreviated Journal NASA/ADS
Volume Issue Pages
Keywords NbN HEB mixers
Abstract Heterodyne receivers for applications in astronomy need quantum-limited sensitivity. At frequencies above 1.4 THz superconducting hot electron bolometers (HEB) can be used to achieve this goal. We present results of the development of a quasi-optical phonon-cooled NbN HEB mixer for GREAT, the German heterodyne receiver for SOFIA. Different mixers with logarithmic spiral and double slot feed antennas have been investigated with respect to their noise temperature, conversion loss, linearity and beam pattern at several frequencies between 0.7 THz and 5.2 THz. At 2.5 THz a double sideband noise temperature of 2200 K was achieved. The conversion loss was 16 dB. The response of the mixer was linear up to 400 K load temperature. This performance was verified by measuring an emission line of methanol at 2.5 THz. The results demonstrate that the NbN HEB is very well suited as a mixer for FIR heterodyne receivers.
Address Monterey, CA
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Area Expedition Conference Far-IR, Sub-mm & MM Detector Technology Workshop, 1-3 April 2002
Notes (up) id.37 Approved no
Call Number Serial 1534
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Author Semenov, Alexei; Hübers, Heinz-Wilhelm; Engel, Andreas; Gol'tsman, Gregory N.
Title Background limited superconducting quantum detector for astronomy Type Abstract
Year 2002 Publication NASA/ADS Abbreviated Journal NASA/ADS
Volume Issue Pages
Keywords SQD
Abstract We present the concept of the superconducting quantum detector for astronomy. Response to a single absorbed photon appears due to successive formation of a normal spot and phase-slip-centers in a narrow strip carrying sub-critical supercurrent. The detector simultaneously has a moderate energy resolution and a variable cut-off wavelength depending on both the material used and operation conditions. We simulated performance of the background-limited direct detector having the 100- micrometer cut-off wavelength. Low dark count rate will allow to realize 10-21 W Hz-1/2 noise equivalent power at 4 K background radiation. The intrinsic recovery time of the counter is rather determined by diffusion of nonequilibrium electrons, thus, thermal fluctuations do not hamper energy resolution of the detector. Provided an appropriate readout technique, the resolution should be better than 1/20 at 50- micrometer wavelength. Planar layout and relatively simple technology favor integration of the detector into an array.
Address Monterey, CA
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Area Expedition Conference Far-IR, Sub-mm & MM Detector Technology Workshop, held 1-3 April 2002
Notes (up) id.62 Approved no
Call Number Serial 1535
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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 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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ISSN 0957-4484 ISBN Medium
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Notes (up) PMID:27782000 Approved no
Call Number Serial 1332
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Author Sahu, Mitrabhanu; Bae, Myung-Ho; Rogachev, Andrey; Pekker, David; Wei, Tzu-Chieh; Shah, Nayana; Goldbart, Paul M.; Bezryadin, Alexey
Title Individual topological tunnelling events of a quantum field probed through their macroscopic consequences Type Journal Article
Year 2009 Publication Nature Phys. Abbreviated Journal Nature Phys.
Volume 5 Issue Pages 503-508
Keywords phase slips, superconducting nanowires
Abstract Phase slips are topological fluctuations that carry the superconducting order-parameter field between distinct current-carrying states. Owing to these phase slips, superconducting nanowires acquire electrical resistance. In such wires, it is well known that at higher temperatures phase slips occur through the process of thermal barrier-crossing by the order-parameter field. At low temperatures, the general expectation is that phase slips should proceed through quantum tunnelling events, which are known as quantum phase slips. However, resistive measurements have produced evidence both for and against the occurrence of quantum phase slips. Here, we report evidence for the observation of individual quantum phase-slip events in homogeneous ultranarrow wires at high bias currents. We accomplish this through measurements of the distribution of switching currents for which the width exhibits a rather counter-intuitive, monotonic increase with decreasing temperature. Importantly, measurements show that in nanowires with larger critical currents, quantum fluctuations dominate thermal fluctuations up to higher temperatures.
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Notes (up) Recommended by Klapwijk Approved no
Call Number Serial 928
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