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Author Annunziata, Anthony J.; Quaranta, Orlando; Santavicca, Daniel F.; Casaburi, Alessandro; Frunzio, Luigi; Ejrnaes, Mikkel; Rooks, Michael J.; Cristiano, Roberto; Pagano, Sergio; Frydman, Aviad; Prober, Daniel E.
Title Reset dynamics and latching in niobium superconducting nanowire single-photon detectors Type Journal Article
Year 2010 Publication J. Appl. Phys. Abbreviated Journal
Volume 108 Issue 8 Pages 7
Keywords SNSPD
Abstract (down) We study the reset dynamics of niobium (Nb) superconducting nanowire single-photon detectors (SNSPDs) using experimental measurements and numerical simulations. The numerical simulations of the detection dynamics agree well with experimental measurements, using independently determined parameters in the simulations. We find that if the photon-induced hotspot cools too slowly, the device will latch into a dc resistive state. To avoid latching, the time for the hotspot to cool must be short compared to the inductive time constant that governs the resetting of the current in the device after hotspot formation. From simulations of the energy relaxation process, we find that the hotspot cooling time is determined primarily by the temperature-dependent electron-phonon inelastic time. Latching prevents reset and precludes subsequent photon detection. Fast resetting to the superconducting state is, therefore, essential, and we demonstrate experimentally how this is achieved. We compare our results to studies of reset and latching in niobium nitride SNSPDs.
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Call Number RPLAB @ gujma @ Serial 649
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Author Vercruyssen, N.; Verhagen, T. G. A.; Flokstra, M. G.; Pekola, J. P.; Klapwijk, T. M.
Title Evanescent states and nonequilibrium in driven superconducting nanowires Type Journal Article
Year 2012 Publication Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 85 Issue Pages 224503(1-10)
Keywords Al HEB, Al superconducting nanowire, global state, bimodal state, quasiclassical kinetic equations, Usadel equation
Abstract (down) We study the nonlinear response of current transport in a superconducting diffusive nanowire between normal reservoirs. We demonstrate theoretically and experimentally the existence of two different superconducting states appearing when the wire is driven out of equilibrium by an applied bias, called the global and bimodal superconducting states. The different states are identified by using two-probe measurements of the wire, and measurements of the local density of states with tunneling probes. The analysis is performed within the framework of the quasiclassical kinetic equations for diffusive superconductors.
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Call Number Serial 898
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Author Bryant, Garnett W.; García de Abajo, F. Javier; Aizpurua, Javier
Title Mapping the Plasmon Resonances of Metallic Nanoantennas Type Journal Article
Year 2008 Publication Nano Letters Abbreviated Journal Nano Lett.
Volume 5 Issue 2 Pages 631-636
Keywords optical antennas
Abstract (down) We study the light scattering and surface plasmon resonances of Au nanorods that are commonly used as optical nanoantennas in analogy to dipole radio antennas for chemical and biodetection field-enhanced spectroscopies and scanned-probe microscopies. With the use of the boundary element method, we calculate the nanorod near-field and far-field response to show how the nanorod shape and dimensions determine its optical response. A full mapping of the size (length and radius) dependence for Au nanorods is obtained. The dipolar plasmon resonance wavelength λ shows a nearly linear dependence on total rod length L out to the largest lengths that we study. However, L is always substantially less than λ/2, indicating the difference between optical nanoantennas and long-wavelength traditional λ/2 antennas. Although it is often assumed that the plasmon wavelength scales with the nanorod aspect ratio, we find that this scaling does not apply except in the extreme limit of very small, spherical nanoparticles. The plasmon response depends critically on both the rod length and radius. Large (500 nm) differences in resonance wavelength are found for structures with different sizes but with the same aspect ratio. In addition, the plasmon resonance deduced from the near-field enhancement can be significantly red-shifted due to retardation from the resonance in far-field scattering. Large differences in near-field and far-field response, together with the breakdown of the simple scaling law must be accounted for in the choice and design of metallic λ/2 nanoantennas. We provide a general, practical map of the resonances for use in locating the desired response for gold nanoantennas.
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Call Number RPLAB @ gujma @ Serial 737
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Author Baeva, E. M.; Titova, N. A.; Kardakova, A. I.; Piatrusha, S. U.; Khrapai, V. S.
Title Universal bottleneck for thermal relaxation in disordered metallic films Type Journal Article
Year 2020 Publication JETP Lett. Abbreviated Journal Jetp Lett.
Volume 111 Issue 2 Pages 104-108
Keywords NbN disordered metallic films, thermal relaxation
Abstract (down) We study the heat relaxation in current biased metallic films in the regime of strong electron–phonon coupling. A thermal gradient in the direction normal to the film is predicted, with a spatial temperature profile determined by the temperature-dependent heat conduction. In the case of strong phonon scattering, the heat conduction occurs predominantly via the electronic system and the profile is parabolic. This regime leads to the linear dependence of the noise temperature as a function of bias voltage, in spite of the fact that all the dimensions of the film are large compared to the electron–phonon relaxation length. This is in stark contrast to the conventional scenario of relaxation limited by the electron–phonon scattering rate. A preliminary experimental study of a 200-nm-thick NbN film indicates the relevance of our model for materials used in superconducting nanowire single-photon detectors.
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ISSN 0021-3640 ISBN Medium
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Call Number Serial 1164
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Author Kuznetsov, K. A.; Kornienko, V. V.; Vakhtomin, Y. B.; Pentin, I. V.; Smirnov, K. V.; Kitaeva, G. K.
Title Generation and detection of optical-terahertz biphotons via spontaneous parametric downconversion Type Conference Article
Year 2018 Publication Proc. ICLO Abbreviated Journal Proc. ICLO
Volume Issue Pages 303
Keywords NbN HEB applications
Abstract (down) We study spontaneous parametric downconversion (SPDC) in the strongly non-degenerate regime when the idler wave hits the terahertz range. By using the hot-electron bolometer, for the first time the SPDC-generated idler-wave photons were directly detected in the terahertz frequency range. Spectrum of corresponding signal photons was measured using standard technique by the CCD camera. Possible applications of correlated optical-terahertz biphotons are discussed.
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Area Expedition Conference International Conference Laser Optics
Notes Approved no
Call Number Serial 1806
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