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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 Recommended by Klapwijk Approved no
Call Number Serial 928
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Author Ovchinnikov, Yu. N.; Varlamov, A. A.
Title Fluctuation-dissipative phenomena in a narrow superconducting channel carrying current below critical Type Journal Article
Year 2009 Publication arXiv Abbreviated Journal
Volume 0910.2659v1 Issue Pages 1-4
Keywords superconducting nanowire, resistance calculation
Abstract The theory of current transport in a narrow superconducting channel accounting for thermal fluctuations is developed. These fluctuations result in the appearance of small but finite dissipation in the sample. The value of corresponding voltage is found as the function of temperature (close to transition temperature) and arbitrary bias current. It is demonstrated that the value of the activation energy (exponential factor in the Arrenius law) when current approaches to the critical one is proportional to (1-J/Jc)^(5/4). This result is in concordance with the one for the affine phenomenon of the Josephson current decay due to the thermal phase fluctuations, where the activation energy proportional (1-J/J_c)^(3/2)(the difference in the exponents is related to the additional current dependence of the order parameter). Found dependence of the activation energy on current explains the enormous discrepancy between the theoretically predicted before and the experimentally observed broadening of the resistive transition.
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Notes arXiv:0910.2659v1; 4 pages, 3 figures Approved no
Call Number Serial 931
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Author Korneeva, Yuliya; Florya, Irina; Vdovichev, Sergey; Moshkova, Mariya; Simonov, Nikita; Kaurova, Natalia; Korneev, Alexander; Goltsman, Gregory
Title Comparison of hot-spot formation in NbN and MoN thin superconducting films after photon absorption Type Conference Article
Year 2017 Publication IEEE Transactions on Applied Superconductivity Abbreviated Journal IEEE Transactions on Applied Superconductiv
Volume 27 Issue 4 Pages 5
Keywords Thin film devices, Superconducitng photoncounting devices, Nanowire single-photon detectors
Abstract In superconducting single-photon detectors SSPD

the efficiency of local suppression of superconductivity and hotspot

formation is controlled by diffusivity and electron-phonon

interaction time. Here we selected a material, 3.6-nm-thick MoNx

film, which features diffusivity close to those of NbN traditionally

used for SSPD fabrication, but with electron-phonon interaction

time an order of magnitude larger. In MoNx detectors we study

the dependence of detection efficiency on bias current, photon

energy, and strip width and compare it with NbN SSPD. We

observe non-linear current-energy dependence in MoNx SSPD

and more pronounced plateaus in dependences of detection

efficiency on bias current which we attribute to longer electronphonon

interaction time.
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Notes Approved no
Call Number RPLAB @ kovalyuk @ Serial 1114
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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 PMID:27782000 Approved no
Call Number Serial 1332
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Author Елезов, М. С.; Щербатенко, М. Л.; Сыч, Д. В.; Гольцман, Г. Н.
Title Практические особенности работы оптоволоконного квантового приемника Кеннеди Type Conference Article
Year 2019 Publication Proc. IWQO Abbreviated Journal Proc. IWQO
Volume Issue Pages 303-305
Keywords Kennedy quantum receiver, fiber, quantum optics, standard quantum limit, superconducting nanowire single-photon detector, coherent detection
Abstract Мы рассматриваем практические особенности работы квантового приемника на основе схемы Кеннеди, собранного из стандартных оптоволоконных элементов и сверхпроводникового детектора одиночных фотонов. Приемник разработан для различения двух фазовомодулированных когерентных состояний света на длине волны 1,5 микрона в непрерывном режиме с частотой модуляции 200 КГц и уровнем ошибок различения примерно в два раза ниже стандартного квантового предела.
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Language Russian Summary Language Original Title
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Notes Duplicated as 1288 Approved no
Call Number Serial 1283
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