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Author Beck, M.; Klammer, M.; Lang, S.; Leiderer, P.; Kabanov, V. V.; Gol’tsman, G. N.; Demsar, J.
Title Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy Type Miscellaneous
Year 2011 Publication arXiv Abbreviated Journal
Volume Issue Pages
Keywords NbN thin film, energy gap dynamics
Abstract Using time-domain Terahertz spectroscopy we performed direct studies of the photoinduced suppression and recovery of the superconducting gap in a conventional BCS superconductor NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the bare quasiparticle recombination rate, the Cooper pair-breaking rate and the electron-phonon coupling constant, \lambda = 1.1 +/- 0.1, which is in excellent agreement with theoretical estimates.
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Notes Duplicated as 641 Approved no
Call Number Serial 1388
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Author Tret’yakov, I. V.; Ryabchun, S. A.; Kaurova, N. S.; Larionov, P. A.; Lobastova, A. A.; Voronov, B. M.; Finkel, M. I.; Gol’tsman, G. N.
Title Optimum absorbed heterodyne power for superconducting NbN hot-electron bolometer mixer Type Journal Article
Year 2010 Publication Tech. Phys. Lett. Abbreviated Journal Tech. Phys. Lett.
Volume 36 Issue 12 Pages 1103-1105
Keywords NbN HEB mixer
Abstract Absorbed heterodyne power has been measured in a low-noise broadband hot-electron bolometer (HEB) mixer for the terahertz range, operating on the effect of electron heating in the resistive state of an ultrathin superconducting NbN film. It is established that the optimum absorbed heterodyne power for the HEB mixer operating at 2.5 THz is about 100 nW.
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ISSN 1063-7850 ISBN Medium
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Notes Approved no
Call Number Serial 1389
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Author Korneev, Alexander; Korneeva, Yulia; Florya, Irina; Elezov, Michael; Manova, Nadezhda; Tarkhov, Michael; An, Pavel; Kardakova, Anna; Isupova, Anastasiya; Chulkova, Galina; Voronov, Boris
Title Recent advances in superconducting NbN single-photon detector development Type Conference Article
Year 2011 Publication Proc. SPIE Abbreviated Journal Proc. SPIE
Volume 8072 Issue Pages 807202 (1 to 10)
Keywords SSPD
Abstract Superconducting single-photon detector (SSPD) is a planar nanostructure patterned from 4-nm-thick NbN film deposited on sapphire substrate. The sensitive element of the SSPD is 100-nm-wide NbN strip. The device is operated at liquid helium temperature. Absorption of a photon leads to a local suppression of superconductivity producing subnanosecond-long voltage pulse. In infrared (at 1550 nm and longer wavelengths) SSPD outperforms avalanche photodiodes in terms of detection efficiency (DE), dark counts rate, maximum counting rate and timing jitter. Efficient single-mode fibre coupling of the SSPD enabled its usage in many applications ranging from single-photon sources research to quantum cryptography. Recently we managed to improve the SSPD performance and measured 25% detection efficiency at 1550 nm wavelength and dark counts rate of 10 s-1. We also improved photon-number resolving SSPD (PNR-SSPD) which realizes a spatial multiplexing of incident photons enabling resolving of up to 4 simultaneously absorbed photons. Another improvement is the increase of the photon absorption using a λ/4 microcavity integrated with the SSPD. And finally in our strive to increase the DE at longer wavelengths we fabricated SSPD with the strip almost twice narrower compared to the standard 100 nm and demonstrated that in middle infrared (about 3 μm wavelength) these devices have DE several times higher compared to the traditional SSPDs.
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Notes Approved no
Call Number RPLAB @ gujma @ Serial 663
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Author Manova, N. N.; Korneeva, Yu. P.; Korneev, A. A.; Slysz, W.; Voronov, B. M.; Gol'tsman, G. N.
Title Superconducting NbN single-photon detector integrated with quarter-wave resonator Type Journal Article
Year 2011 Publication Tech. Phys. Lett. Abbreviated Journal Tech. Phys. Lett.
Volume 37 Issue 5 Pages 469-471
Keywords SSPD, SNSPD
Abstract The spectral dependence of the quantum efficiency of superconducting NbN single-photon detectors integrated with quarter-wave resonators based on Si3N4, SiO2, and SiO layers has been studied.
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Notes Approved no
Call Number RPLAB @ gujma @ Serial 664
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Author Dauler, Eric; Kerman, Andrew; Robinson, Bryan; Yang, Joel; Voronov, Boris; Goltsman, Gregory; Hamilton, Scott; Berggren, Karl
Title Photon-number-resolution with sub-30-ps timing using multi-element superconducting nanowire single photon detectors Type Journal Article
Year 2009 Publication J. Modern Opt. Abbreviated Journal J. Modern Opt.
Volume 56 Issue 2 Pages 364-373
Keywords PNR SSPD; SNSPD; photon-number-resolution; superconducting nanowire single photon detector; timing jitter; system detection efficiency
Abstract A photon-number-resolving detector based on a four-element superconducting nanowire single photon detector is demonstrated to have sub-30-ps resolution in measuring the arrival time of individual photons. This detector can be used to characterize the photon statistics of non-pulsed light sources and to mitigate dead-time effects in high-speed photon counting applications. Furthermore, a 25% system detection efficiency at 1550 nm was demonstrated, making the detector useful for both low-flux source characterization and high-speed photon-counting and quantum communication applications. The design, fabrication and testing of this detector are described, and a comparison between the measured and theoretical performance is presented.
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Notes Approved no
Call Number RPLAB @ gujma @ Serial 700
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