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Author Beck, Matthias; Leiderer, Paul; Kabanov, Viktor V.; Gol'tsman, Gregory; Helm, Manfred; Demsar, Jure
Title Energy-gap dynamics of a superconductor NbN studied by time-resolved terahertz spectroscopy Type Abstract
Year 2012 Publication INIS Abbreviated Journal INIS
Volume 45 Issue 12 Pages (down) 1-3
Keywords NbN energy gap
Abstract Using time-resolved terahertz (THz) spectroscopy we performed direct studies of the photoinduced suppression and recovery of the SC gap in a conventional SC 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 important microscopic constants: the Cooper pair-breaking rate via phonon absorption and the bare quasiparticle recombination rate. From the latter we were able to extract the dimensionless electron-phonon coupling constant, λ=1.1±0.1, in excellent agreement with theoretical estimates. The technique also allowed us to determine the absorbed energy required to suppress SC, which in NbN equals the thermodynamic condensation energy (in cuprates the two differ by an order of magnitude). Finally, we present the first studies of dynamics following resonant excitation with intense narrow band THz pulses tuned to above and below the superconducting gap. These suggest an additional process, particularly pronounced near Tc, that could be attributed to amplification of SC via effective quasiparticle cooling.
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Call Number Serial 1383
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Author Pentin, I. V.; Smirnov, A. V.; Ryabchun, S. A.; Gol’tsman, G. N.; Vaks, V. L.; Pripolzin, S. I.; Paveliev, D. G.
Title Heterodyne source of THz range based on semiconductor superlattice multiplier Type Conference Article
Year 2011 Publication IRMMW-THz Abbreviated Journal IRMMW-THz
Volume Issue Pages (down) 1-2
Keywords NbN HEB mixer, superlattice
Abstract We present the results of our studies of the possibility of developing a heterodyne receiver incorporating a hot-electron bolometer mixer as the detector and a semiconductor superlattice multiplier driven by a reference synthesizer as the local oscillator. We observe that such a local oscillator offers enough power in the terahertz range to pump the HEB into the operating state.
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Call Number 6105209 Serial 1384
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Author Slysz, W.; Wegrzecki, M.; Papis, E.; Gol'tsman, G. N.; Verevkin, A.; Sobolewski, R.
Title A method of optimization of the NbN superconducting single-photon detector Type Miscellaneous
Year 2004 Publication INIS Abbreviated Journal INIS
Volume 36 Issue 27 Pages (down) 1-2
Keywords NbN SSPD, SNSPD
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Area Expedition Conference 5-th International Symposium Ion Implantation and Other Applications of Ions and Electrons, ION
Notes Reference num. 36060124 Approved no
Call Number Serial 1485
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Author Slysz, W.; Wegrzecki, M.; Bar, J.; Grabiec, P.; Gol'tsman, G. N.; Verevkin, M.; Sobolewski, R.
Title NbN superconducting single-photon detectors coupled with a communication fiber Type Miscellaneous
Year 2004 Publication INIS Abbreviated Journal INIS
Volume 37 Issue 2 Pages (down) 1-2
Keywords NbN SSPD, SNSPD
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Address Stare Jablonki, Poland
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Area Expedition Conference 8-th Electron Technology Conference ELTE
Notes Approved no
Call Number Serial 1486
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Author Sobolewski, R.; Zhang, J.; Slysz, W.; Pearlman, A.; Verevkin, A.; Lipatov, A.; Okunev, O.; Chulkova, G.; Korneev, A.; Smirnov, K.; Kouminov, P.; Voronov, B.; Kaurova, N.; Drakinsky, V.; Goltsman, G. N.
Title Ultrafast superconducting single-photon optical detectors Type Conference Article
Year 2003 Publication Proc. SPIE Abbreviated Journal Proc. SPIE
Volume 5123 Issue Pages (down) 1-11
Keywords NbN SSPD, SNSPD
Abstract We present a new class of single-photon devices for counting of both visible and infrared photons. Our superconducting single-photon detectors (SSPDs) are characterized by the intrinsic quantum efficiency (QE) reaching up to 100%, above 10 GHz counting rate, and negligible dark counts. The detection mechanism is based on the photon-induced hotspot formation and subsequent appearance of a transient resistive barrier across an ultrathin and submicron-wide superconducting stripe. The devices are fabricated from 3.5-nm-thick NbN films and operate at 4.2 K, well below the NbN superconducting transition temperature. Various continuous and pulsed laser sources in the wavelength range from 0.4 μm up to >3 μm were implemented in our experiments, enabling us to determine the detector QE in the photon-counting mode, response time, and jitter. For our best 3.5-nm-thick, 10×10 μm2-area devices, QE was found to reach almost 100% for any wavelength shorter than about 800 nm. For longer-wavelength (infrared) radiation, QE decreased exponentially with the photon wavelength increase. Time-resolved measurements of our SSPDs showed that the system-limited detector response pulse width was below 150 ps. The system jitter was measured to be 35 ps. In terms of the counting rate, jitter, and dark counts, the NbN SSPDs significantly outperform their semiconductor counterparts. Already identifeid and implemented applications of our devices range from noninvasive testing of semiconductor VLSI circuits to free-space quantum communications and quantum cryptography.
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Publisher SPIE Place of Publication Editor Spigulis, J.; Teteris, J.; Ozolinsh, M.; Lusis, A.
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Area Expedition Conference Advanced Optical Devices, Technologies, and Medical Applications
Notes Approved no
Call Number Serial 1513
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