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Verevkin, A. A., Zhang, J., Slysz, W., Sobolewski, R., Lipatov, A. P., Okunev, O., et al. (2002). Superconducting single-photon detectors for GHz-rate free-space quantum communications. In J. C. Ricklin, & D. G. Voelz (Eds.), Proc. SPIE (Vol. 4821, pp. 447–454). SPIE.
Abstract: We report our studies on the performance of new NbN ultrathin-film superconducting single-photon detectors (SSPDs). Our SSPDs exhibit experimentally measured quantum efficiencies from 5% at wavelength λ = 1550 nm up to 10% at λ = 405 nm, with exponential, activation-energy-type spectral sensitivity dependence in the 0.4-μm – 3-μm wavelength range. Using a variable optical delay setup, we have shown that our NbN SSPDs can resolve optical photons with a counting rate up to 10 GHz, presently limited by the read-out electronics. The measured device jitter was below 35 ps under optimum biasing conditions. The extremely high photon counting rate, together with relatively high (especially for λ > 1 μm) quantum efficiency, low jitter, and very low dark counts, make NbN SSPDs very promising for free-space communications and quantum cryptography.
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Goltsman, G. N. (2021). Development and applications of terahertz hot electron bolometers. In 1st Moscow Int. Conf. on Submillimeter and Millimeter Astronomy: Objectives and Instruments.
Abstract: The development of techniques and technologies for the deposition of ultrathin superconducting films, the creation of superconducting structures on a nanometer scale is the basis of significant progress in the field of superconducting receiving systems. Ultrathin NbN films are the basis for a wide range of record-breaking hot electron devices: direct and heterodyne terahertz detectors. Terahertz receivers are especially in demand in high-resolution spectroscopy for astronomical, atmospheric, and medical research. HEB receivers are widely used in terahertz radio astronomy. For example, the Dutch SRON Institute is preparing a project for the GUSTO hot air balloon telescope with a HEB mixer array at 1.4 THz and 1.9 THz. A 5-meter Chinese terahertz telescope DATE5 with HEB mixers at 1.4 THz is installed at the South Pole. The Stratospheric Observatory (SOFIA) uses HEB mixer matrices in the GREAT instrument operating in the 1.2 – 4.7 THz range. It is planned to implement the international project Origins Space Telescope (OST) in the far infrared region based on HEB receivers. The Japanese project Smiles-2 will allow measurements at 1.8 THz in the upper layers of the stratosphere and mesosphere. The development of the Millimetron space observatory continues in Russia.
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Semenov, A., Hübers, H. - W., Engel, A., & Gol'tsman, G. N. (2002). Background limited superconducting quantum detector for astronomy. In NASA/ADS.
Abstract: We present the concept of the superconducting quantum detector for astronomy. Response to a single absorbed photon appears due to successive formation of a normal spot and phase-slip-centers in a narrow strip carrying sub-critical supercurrent. The detector simultaneously has a moderate energy resolution and a variable cut-off wavelength depending on both the material used and operation conditions. We simulated performance of the background-limited direct detector having the 100- micrometer cut-off wavelength. Low dark count rate will allow to realize 10-21 W Hz-1/2 noise equivalent power at 4 K background radiation. The intrinsic recovery time of the counter is rather determined by diffusion of nonequilibrium electrons, thus, thermal fluctuations do not hamper energy resolution of the detector. Provided an appropriate readout technique, the resolution should be better than 1/20 at 50- micrometer wavelength. Planar layout and relatively simple technology favor integration of the detector into an array.
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Hübers, H. - W., Semenov, A., Richter, H., Smirnov, K., Gol'tsman, G., & Voronov, B. (2002). Phonon cooled far-infrared hot electron bolometer mixer. In NASA/ADS.
Abstract: Heterodyne receivers for applications in astronomy need quantum-limited sensitivity. At frequencies above 1.4 THz superconducting hot electron bolometers (HEB) can be used to achieve this goal. We present results of the development of a quasi-optical phonon-cooled NbN HEB mixer for GREAT, the German heterodyne receiver for SOFIA. Different mixers with logarithmic spiral and double slot feed antennas have been investigated with respect to their noise temperature, conversion loss, linearity and beam pattern at several frequencies between 0.7 THz and 5.2 THz. At 2.5 THz a double sideband noise temperature of 2200 K was achieved. The conversion loss was 16 dB. The response of the mixer was linear up to 400 K load temperature. This performance was verified by measuring an emission line of methanol at 2.5 THz. The results demonstrate that the NbN HEB is very well suited as a mixer for FIR heterodyne receivers.
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Gershenzon, E. M., Gol’tsman, G. N., Sergeev, A., & Semenov, A. D. (1990). Picosecond response of YBaCuO films to electromagnetic radiation. In W. Gorzkowski, M. Gutowski, A. Reich, & H. Szymczak (Eds.), Proc. European Conf. High-Tc Thin Films and Single Crystals (pp. 457–462).
Abstract: Radiation-induced change of the resistance was studied in the resistive state of YBaCuO films. Electron-phonon relaxation time T h was determmed from direct ep measurements and analysis of quasistationary electron heating. Temperature dependence of That TS 40 K was found to – ep be T h.. T'. The resul ts show that ep detectors with the response time of few picosecond at nitrogen temperature can be realized.
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