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Author Beck, M.; Klammer, M.; Lang, S.; Leiderer, P.; Kabanov, V. V.; Gol'tsman, G. N.; Demsar, J. doi  openurl
  Title Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy Type Journal Article
  Year 2011 Publication Phys. Rev. Lett. Abbreviated Journal (up) Phys. Rev. Lett.  
  Volume 107 Issue 17 Pages 4  
  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, λ=1.1±0.1, which is in excellent agreement with theoretical estimates.  
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  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 641  
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Author Beck, M.; Rousseau, I.; Klammer, M.; Leiderer, P.; Mittendorff, M.; Winnerl, S.; Helm, M.; Gol'tsman, G.N.; Demsar, J. url  doi
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  Title Transient increase of the energy gap of superconducting NbN thin films excited by resonant narrow-band terahertz pulses Type Journal Article
  Year 2013 Publication Phys. Rev. Lett. Abbreviated Journal (up) Phys. Rev. Lett.  
  Volume 110 Issue 26 Pages 267003 (1 to 5)  
  Keywords NbN thin films, energy gap  
  Abstract Observations of radiation-enhanced superconductivity have thus far been limited to a few type-I superconductors (Al, Sn) excited at frequencies between the inelastic scattering rate and the superconducting gap frequency 2Delta/h. Utilizing intense, narrow-band, picosecond, terahertz pulses, tuned to just below and above 2Delta/h of a BCS superconductor NbN, we demonstrate that the superconducting gap can be transiently increased also in a type-II dirty-limit superconductor. The effect is particularly pronounced at higher temperatures and is attributed to radiation induced nonthermal electron distribution persisting on a 100 ps time scale.  
  Address Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457, Germany  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0031-9007 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:23848912 Approved no  
  Call Number Serial 1370  
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Author Gol'tsman, G. N.; Korneev, A.; Rubtsova, I.; Milostnaya, I.; Chulkova, G.; Minaeva, O.; Smirnov, K.; Voronov, B.; Słysz, W.; Pearlman, A.; Verevkin, A.; Sobolewski, R. url  doi
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  Title Ultrafast superconducting single-photon detectors for near-infrared-wavelength quantum communications Type Journal Article
  Year 2005 Publication Phys. Stat. Sol. (C) Abbreviated Journal (up) Phys. Stat. Sol. (C)  
  Volume 2 Issue 5 Pages 1480-1488  
  Keywords NbN SSPD, SNSPD  
  Abstract We present our progress on the research and development of NbN superconducting single‐photon detectors (SSPD's) for ultrafast counting of near‐infrared photons for secure quantum communications. Our SSPD's operate in the quantum detection mode based on the photon‐induced hotspot formation and subsequent development of a transient resistive barrier across an ultrathin and submicron‐width superconducting stripe. The devices are fabricated from 4‐nm‐thick NbN films and kept in the 4.2‐ to 2‐K temperature range. The detector experimental quantum efficiency in the photon‐counting mode reaches above 40% for the visible light and up to 30% in the 1.3‐ to 1.55‐µm wavelength range with dark counts below 0.01 per second. The experimental real‐time counting rate is above 2 GHz and is limited by our readout electronics. The SSPD's timing jitter is below 18 ps, and the best‐measured value of the noise‐equivalent power (NEP) is 5 × 10–21 W/Hz1/2 at 1.3 µm. In terms of quantum efficiency, timing jitter, and maximum counting rate, our NbN SSPD's significantly outperform semiconductor avalanche photodiodes and photomultipliers in the 1.3‐ to 1.55‐µm range.  
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  Series Volume Series Issue Edition  
  ISSN 1610-1634 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1479  
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Author Peltonen, J. T.; Peng, Z. H.; Korneeva, Yu. P.; Voronov, B. M.; Korneev, A. A.; Semenov, A. V.; Gol'tsman, G. N.; Tsai, J. S; Astafiev, Oleg doi  openurl
  Title Coherent dynamics and decoherence in a superconducting weak link Type Journal Article
  Year 2016 Publication Physic. Rev. B, Abbreviated Journal (up) Physic. Rev. B,  
  Volume 94 Issue Pages 180508  
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  Notes Approved no  
  Call Number RPLAB @ akorneev @ Serial 1123  
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Author Aksaev, E. E.; Gershenzon, E.M.; Gol'tsman, G. N.; Mirskij, G. I.; Semenov, A. D. url  openurl
  Title Submillimetric spectrometer-relaxometer based on backward-wave tubes with picosecond time resolution Type Journal Article
  Year 1991 Publication Pribory i Tekhnika Eksperimenta Abbreviated Journal (up) Pribory i Tekhnika Eksperimenta  
  Volume 34 Issue 2 Pages 125-131  
  Keywords BWO, applications  
  Abstract The high-sensitive automatic spectrometer-relaxometer based on backward-wave tubes in the range of 4÷0.25 mm was described permitting to study the response kinetics of sample under investigation in any point of this range with the resolution time of 10-11 s. The relaxation measurements were conducted using oscillation beats of two adequate tubes, the frequency of one of them was fixed, while that of the other one was changeable. The amplitude-frequency characteristic of the response under the conditions of synchronous reception was recorded at beat frequency variation from 107 to 1010 Hz. The high sensitivity was reached by decreasing the device recording band down to 100 Hz in the whole measuring range.  
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  Series Volume Series Issue Edition  
  ISSN 0032-8162 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1683  
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Author Gershenzon, E. M.; Gol'tsman, G. N.; Mirskii, G. I. url  openurl
  Title Submillimeter backward-wave-tube spectrometer-relaxometer Type Journal Article
  Year 1987 Publication Pribory i Tekhnika Eksperimenta Abbreviated Journal (up) Pribory i Tekhnika Eksperimenta  
  Volume 30 Issue 4 Pages 131-137  
  Keywords BWO, applications  
  Abstract A backward-wave-tube (BWT) spectrometer-relaxometer is described that is designed for study of the relaxation characteristics of photoconductors in the wavelength range of 2-0.25 mm – in particular, to measure the relaxation times of the submillimeter photoconductivity of germanium in the range of 10[sup:-4]-10[sup:-9] sec and to determine from these data the concentration of compensating impurities of from 10[sup:10] to 10[sup:14] cm[sup:-3]. The instrument uses the beats of the oscillations of two BWTs and records the amplitude-frequency response of the specimen with variation of the beat frequency from 10[sup:4] to 10[sup:8] Hz with accumulation of the desired signal for less than or equal to1 sec by means of a quadrature synchronous detector. The beat frequency is stabilized and the quadrature voltages of the synchronous detector are formed by means of phase-locked loops.  
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  Language Russian Summary Language Original Title  
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  Notes Approved no  
  Call Number Serial 1699  
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Author Gershenzon, E. M.; Gol'tsman, G. N.; Semenov, A. D. url  openurl
  Title Submillimeter backward wave tube spectrometer for measuring superconducting film transmission Type Journal Article
  Year 1983 Publication Pribory i Tekhnika Eksperimenta Abbreviated Journal (up) Pribory i Tekhnika Eksperimenta  
  Volume 26 Issue 5 Pages 134-137  
  Keywords BWO spectroscopy, spectrometer, transmission  
  Abstract A spectrometer employing six backward wave tubes is described. It is intended for investigation of superconductors in the 0.2-3 mm range of wave lengths. During the measurement of the transmission spectrum it is possible to determine the energy gap for superconduct1ng films 50 to 4000 A thick. The transmission factor can vary from 10-1 to 10-9. Spectrum of relation of film transmission factors in superconducting and normal states is measured for determining the energy gap 2 Δ. The transmission spectrum obtained by means of a computer for vanadium film 300 A thick is given as an example. The energy gap 2 Δ = 1.4 MeV  
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  Language Russian Summary Language Original Title  
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  ISSN 0032-8162 ISBN Medium  
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  Notes Субмиллиметровый спектрометр с лампами обратной волны для измерения пропускания сверхпроводниковых пленок Approved no  
  Call Number Serial 1713  
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Author Cherednichenko, S.; Ronnung, F.; Gol'tsman, G.; Gershenzon, E.; Winkler, D. url  openurl
  Title YBa2Cu3O7-δ hot-electron bolometer with submicron dimensions Type Conference Article
  Year 1999 Publication Proc. 10th Int. Symp. Space Terahertz Technol. Abbreviated Journal (up) Proc. 10th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 181-189  
  Keywords YBCO HTS HEB mixers  
  Abstract Photoresponse of YBa2Cu3O7-δ hot-electron bolometers to modulated near-infrared radiation was studied at a modulation .frequenc y var y ing from 0.2 MHz to 2 GHz. Bolometers were _fabricated from a 50 12 M thick film and had in-plane areas of 10x10 , um 2 . 2x0.2 s um', 1x0.2 p.m', and 0.5x0.2 jim. We found that nonequilibrium phonons cool down more effectively for the bolometers with smaller area. For the smallest bolometer the bolometric component in the response is 10 dB less than for the largest one.  
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  Notes Approved no  
  Call Number Serial 1572  
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Author Schubert, J.; Semenov, A.; Gol'tsman, G.; Hübers, H.-W.; Schwaab, G.; Voronov, B.; Gershenzon, E. url  openurl
  Title Noise temperature and sensitivity of a NbN hot-electron mixer at frequencies from 0.7 THz to 5.2 THz Type Conference Article
  Year 1999 Publication Proc. 10th Int. Symp. Space Terahertz Technol. Abbreviated Journal (up) Proc. 10th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 190-199  
  Keywords NbN HEB mixers  
  Abstract We report on noise temperature measurements of a NbN phonon-cooled hot-electron bolometric mixer at different bias regimes. The device was a 3 nm thick bridge with in-plane dimensions of 1.7 x 0.2 gm 2 integrated in a complementary logarithmic spiral antenna. Measurements were performed at frequencies ranging from 0.7 THz up to 5.2 THz. The measured DSB noise temperatures are 1500 K (0.7 THz), 2200 K (1.4 THz), 2600 K (1.6 THz), 2900 K (2.5 THz), 4000 K (3.1 THz) 5600 K (4.3 THz) and 8800 K (5.2 THz). Two bias regimes are possible in order to achieve low noise temperatures. But only one of them yields sensitivity fluctuations close to the theoretical limit.  
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  Notes Approved no  
  Call Number Serial 1573  
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Author Gerecht, E.; Musante, C. F.; Jian, H.; Zhuang, Y.; Yngvesson, K. S.; Dickinson, J.; Goyette, T.; Waldman, J.; Yagoubov, P. A.; Gol'tsman, G. N.; Voronov, B. M.; Gershenzon, E. M. url  openurl
  Title Improved characteristics of NbN HEB mixers integrated with log-periodic antennas Type Conference Article
  Year 1999 Publication Proc. 10th Int. Symp. Space Terahertz Technol. Abbreviated Journal (up) Proc. 10th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 200-207  
  Keywords NbN HEB mixers  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1574  
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