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Gershenzon EM, Gol'tsman GN, Karasik BS, Lugovaya GY, Serebryakova NA, Chinkova EV. Infrared radiation detectors on the base of electron heating in resistive state films from traditional superconducing materials. Sverkhprovodimost': Fizika, Khimiya, Tekhnika. 1992;5(6):1129–40.
Abstract: Characteristics of infrared radiation detectors based on electron heating in thin superconducting films transformed at T ≤ Tc to a resistive state by transport current and, if necessary, by magnetic field are investigated. A comparison is made of the characteristics of the detectors fabricated of different materials: aluminium, niobium, Mo0.5Re0.5. Some devices with different topology of the reception area are considered. Electron heating detectors are comparable by their sensitivity with superconducting bolometers, but differ in a high fast-response.
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Voronov BM, Gershenzon EM, Gol'tsman GN, Gogidze IG, Gusev YP, Zorin MA, et al. Picosecond range detector base on superconducting niobium nitride film sensitive to radiation in spectral range from millimeter waves up to visible light. Sverkhprovodimost': Fizika, Khimiya, Tekhnika. 1992;5(5):955–60.
Abstract: Fast-operating picosecond detector of electromagnetical radiation is developed on the basis of fine superconducting film of niobium nitride with high sensitivity within spectral range from millimetric waves up to visible light. Detector sensitive element represents structure covering narrow parallel strips with micron sizes included in the rupture of microstrip line. Detecting ability of the detector and time constant measured using amplitude-simulated radiation of reverse wave tubes and pulse radiation of picosecond gas and solid-body lasers, constitute D*≅1010 W-1·cm·Hz-1/2 and τ≤5 ps respectively, at 10 K temperature. The expected value of time constant of the detector at 10 K obtained via extrapolation of directly measured dependence that is, τ ∝ τ-1, constitutes 20 ps. Experimental data demonstrate that detection mechanism is linked with electron heating effect.
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Gershenzon EM, Gol'tsman GN, Dzardanov AL, Elant'ev AI, Zorin MA, Markin AG, et al. S-N switching of niobium and YBCO films: limit time and perspective of fast key element creation. Sverkhprovodimost': Fizika, Khimiya, Tekhnika. 1992;5(12):2386–402.
Abstract: A study was made on processes of switching of thin niobium film strips between superconducting and normal states under the effect of optical radiation pulse and voltage step. The results are described satisfactorily by the model of spatial homogeneous electron heating. It is shown that limiting switching times can be equal to several shares of nanosecond at 4.2 K. Preliminary results for YBa2Cu3O-7-x films are presented. Prospects and advantages of creation of ducting structures of narrow streps, are discussed.
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Gershenzon EM, Gol'tsman GN, Dzardanov AL, Kuznetsov EA. Superconducting UHF-limiter based on electron heating up. Sverkhprovodimost': Fizika, Khimiya, Tekhnika. 1992;5(11):2164–70.
Abstract: The results of experimental investigation of fast-action 5HF-limiter are presented; the limiter is based on the utilization of electron hetaing phenomenon in thin superconducting films. The design of SHF-limiter, which is intended for operation at liquid helium temperatures and which has the form of a section of superconducting NbN microstrip line for 1-12 GHz rang, is described.
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Gershenzon EM, Gol'tsman GN, Gogidze IG, Gusev YP, Elantiev AI, Karasik BS, et al. Millimeter and submillimeter wave range mixer based on electronic heating of superconducting films in the resistive state. Sov Supercond. 1990;3(10):1582–97.
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Varyukhin SV, Zakharov AA, Gershenzon EM, Gol'tsman GN, Ptitsina NG, Chulkova GM. Low energy excitation in La2CuO4. Sverkhprovodimost': Fizika, Khimiya, Tekhnika. 1990;3(5):832–7.
Abstract: Measurements of transmission and photoconductivity spectra in submillimeter wave length range as well as of capacity C and conductivity G in the region of acoustic frequencies of metal-dielectric-La2CuO4 system at low temperatures are performed using La2CuO4 monocrystals. Optical spectra posses a threshold character, a sharp decrease of transmission and photocoductivity signal occurs in the energy region hν>1.5 MeV. C(ω,T) and G(ω, T) dependences have a universal form typical of Debye type relaxation processes. Relaxation time dependence is of thermoactivated character τ(T)∼exp(ξ/T) with the gap value ξ≅2 meV. It is assumed that excitations with characteristic energy of ∼2 meV exist in La2CuO4. A possible nature of the detected low-energy excitations is discussed.
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Gershenzon EM, Gol'tsman GN, Semenov AD. Submillimeter backward wave tube spectrometer for measuring superconducting film transmission. Pribory i Tekhnika Eksperimenta. 1983;26(5):134–7.
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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Blagosklonskaya LE, Gershenzon EM, Gol'tsman GN, Elant'ev AI. Effect of a high magnetic field on the spectrum of donors in InSb. Fizika i Tekhnika Poluprovodnikov. 1977;11(12):2373–5.
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Lusche R, Semenov A, Huebers H-W, Ilin K, Siegel M, Korneeva Y, et al. Effect of the wire geometry and an externally applied magnetic field on the detection efficiency of superconducting nanowire single-photon detectors [abstract]. In: INIS. Vol 46.; 2013. p. 1–3.
Abstract: The interest in single-photon detectors in the near-infrared wavelength regime for applications, e.g. in quantum cryptography has immensely increased in the last years. Superconducting nanowire single-photon detectors (SNSPD) already show quite reasonable detection efficiencies in the NIR which can even be further improved. Novel theoretical approaches including vortex-assisted photon counting state that the detection efficiency in the long wavelength region can be enhanced by the detector geometry and an applied magnetic field. We present spectral measurements in the wavelength range from 350-2500 nm of the detection efficiency of meander-type TaN and NbN SNSPD with varying nanowire line width from 80 to 250 nm. Due to the used experimental setup we can accurately normalize the measured spectra and are able to extract the intrinsic detection efficiency (IDE) of our detectors. The results clearly indicate an improvement of the IDE depending on the wire width according to the theoretic models. Furthermore we experimentally found that the smallest detectable photon-flux can be increased by applying a small magnetic field to the detectors.
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Beck M, Leiderer P, Kabanov VV, Gol'tsman G, Helm M, Demsar J. Energy-gap dynamics of a superconductor NbN studied by time-resolved terahertz spectroscopy [abstract]. In: INIS. Vol 45.; 2012. p. 1–3.
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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