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Author Tong, C. Edward; Trifonov, Andrey; Blundell, Raymond; Shurakov, Alexander; Gol’tsman, Gregory url  openurl
  Title A digital terahertz power meter based on an NbN thin film Type Abstract
  Year 2014 Publication Proc. 25th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 25th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 170  
  Keywords (down) waveguide NbN HEB mixers  
  Abstract We have further studied the effect of subjecting a superconducting Hot Electron Bolometer (HEB) element made from an NbN thin film to microwave radiation. Since the photon energy is weak, the microwave radiation does not simply heat the film, but generates a bi-static state, switching between the superconducting and normal states, upon the application of a small voltage bias. Indeed, a relaxation oscillation of a few MHz has previously been reported in this regime [1]. Switching between the superconducting and normal states modulates the reflected microwave pump power from the device. A simple homodyne setup readily recovers the spontaneous switching waveform in the time domain. The switching frequency is a function of both the bias voltage (DC heating) and the applied microwave power. In this work, we use a 0.8 THz HEB waveguide mixer for the purpose of demonstration. The applied microwave pump, coupled through a directional coupler, is at 1 GHz. Since the pump power is of the order of a few μW, a room temperature amplifier is sufficient to amplify the reflected pump power from the HEB mixer, which beats with the microwave source in a homodyne set-up. After further amplification, the switching waveform is passed onto a frequency counter. The typical frequency of the switching pulses is 3-5 MHz. It is found that the digital frequency count increases with higher microwave pump power. When the HEB mixer is subjected to additional optical power at 0.8 THz, the frequency count also increases. When we vary the incident optical power by using a wire grid attenuator, a linear relationship is observed between the frequency count and the applied optical power, over at least an order of magnitude of power. This phenomenon can be exploited to develop a digital power meter, using a very simple electronics setup. Further experiments are under way to determine the range of linearity and the accuracy of calibration transfer from the microwave to the THz regime. References 1. Y. Zhuang, and S. Yngvesson, “Detection and interpretation of bistatic effects in NbN HEB devices,” Proc. 13 th Int. Symp. Space THz Tech., 2002, pp. 463–472.  
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  Call Number Serial 1366  
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Author Shurakov, Alexander; Tong, Cheuk-yu E.; Blundell, Raymond; Gol’tsman, Gregory url  openurl
  Title A microwave pumped HEB direct detector using a homodyne readout scheme Type Abstract
  Year 2014 Publication Proc. 25th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 25th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 129  
  Keywords (down) waveguide NbN HEB detector, NEP  
  Abstract We report the results of our study on the noise performance of a fast THz detector based on the repurpose of hot electron bolometer mixer (HEB). Instead of operating with an elevated bath temperature, microwave power is injected into the HEB device, which enhances the sensitivity of the detector and at the same time provide a mechanism for reading out impedance changes of the device induced by the modulated incident THz radiation [1]. We have demonstrated an improvement of the detector’s optical noise equivalent power (NEP). Furthermore, by introducing a homodyne readout scheme based on a room temperature microwave mixer, the dynamic range of the detector is increased. The HEB devices used in this work were made of 4 nm thick NbN film. The detector chips were installed into a waveguide mixer block fitted with a corrugated horn, mounted on the cold plate of a liquid helium cryostat. The HEBs were operated at a bath temperature of 4.2 K. The signal beam was terminated on black bodies at ambient and liquid nitrogen temperatures. A chopper wheel placed in front of the cryostat window operating at a frequency of 1.48 kHz modulated the input load temperature of the detector. A cold mesh filter, centered at 830 GHz, was used to define the input signal power bandwidth. Microwave was injected through a broadband directional coupler inside the cryostat. Our experiments were mostly conducted at a pump frequency of 1.5 GHz. The reflected microwave power from the HEB device was fed into a cryogenic low noise amplifier (LNA). The output of the LNA was connected to the RF input port of a room temperature microwave mixer, which beat the reflected signal from the HEB using a copy of the original 1.5 GHz injection signal in a homodyne demodulation scheme. The amplitude of the detected power was measured by a lock-in amplifier, which was synchronized to the chopper frequency. Preliminary results yield an optical NEP of ~1 pW/ Hz 1/2 which corresponds to an improvement of a factor of 3 compared to [1], driven mainly by a lowering of the system noise floor. The dynamic range was also increased by similar amount. References 1. A. Shurakov et al. “A Microwave Pumped Hot Electron Bolometric Direct Detector,” submitted on Oct 18, 2013 to Appl. Phys. Let.  
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  Call Number Serial 1365  
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Author Кардакова, А. И.; Финкель, М. И.; Морозов, Д. В.; Ковалюк, В. В.; Ан, П. П.; Гольцман, Г. Н. url  openurl
  Title Время электрон-фононного взаимодействия в сверхпроводниковых пленках нитрида титана Type Conference Article
  Year 2014 Publication Труды XVIII международного симпозиума «Нанофизика и наноэлектроника» Abbreviated Journal  
  Volume 1 Issue Pages 47-48  
  Keywords (down) TiN films  
  Abstract Определены времена электрон-фононного взаимодействия в тонких сверхпроводниковых пленках нитрида титана. Измеренные значения τ_eph находятся в диапазоне от 5.5 нс до 88 нс при температурах 4,2 К и 1,7 К, соответственно, и соответствуют температурной зависимости Т^-3.  
  Address Нижний Новгород, Россия  
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  Language Russian Summary Language Original Title  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1835  
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Author Averkin, A. S.; Shishkin, A. G.; Chichkov, V. I.; Voronov, B. M.; Goltsman, G. N.; Karpov, A.; Ustinov, A. V. openurl 
  Title Tunable frequency-selective surface based on superconducting split-ring resonators Type Conference Article
  Year 2014 Publication 8th Metamaterials Abbreviated Journal 8th Metamaterials  
  Volume Issue Pages  
  Keywords (down) superconducting split-ring resonators  
  Abstract We study a possibility to use the 2D superconducting metamaterial as a tunable frequency-selective surface (FSS). The proposed FSS is made of sub-wavelength size (l/14) metamaterial unit cells, where a split-ring resonator is embedded in a small iris aperture in a metal plane. The split-ring resonator is made of NbN film, and its resonance frequency is tuned by the temperature of the sample, changing the kinetic inductance of NbN film. The Ansoft HFSS simulation predicts the FSS tuning range of about 10-20 %. The developed superconducting FSS may be used as a tunable band-pass filter or modulator.  
  Address Copenhagen, Denmark  
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  Area Expedition Conference 8th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics – Metamaterials  
  Notes Approved no  
  Call Number Serial 1749  
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Author Gurovich, B. A.; Tarkhov, M. A.; Prikhod'ko, K. E.; Kuleshova, E. A.; Komarov, D. A.; Stolyarov, V. L.; Olshanskii, E. D.; Goncharov, B. V.; Goncharova, D. A.; Kutuzov, L. V.; Domantovskii, A. G. openurl 
  Title Controlled modification of superconducting properties of NbN ultrathin films under composite ion beam irradiation Type Journal Article
  Year 2014 Publication Nanotechnologies in Russia Abbreviated Journal Nanotechnologies in Russia  
  Volume 9 Issue 7 Pages 386-390  
  Keywords (down) superconducting NbN films composite ion beam irradiation protoning  
  Abstract In this work, the results of studying the microstructure and superconducting properties of ultrathin films on the basis of NbN in the initial state and after modification by being subjecting to composite ion beam irradiation with the energy ~1–3) keV are presented. HRTEM analysis showed that the initial films on the sapphire substrate in orientation “c-cut” are characterized by a grain size essentially exceeding the film thickness, while on the other substrates the size of grains corresponds to the thickness of film. Using XPS analysis, it was shown that in the initial films the atomic ratio of Nb and N is 0.51/0.49, respectively, the percentage of oxygen being lower than 5%. For ultrathin films 5 nm in thickness, the critical temperature of transit to superconducting state (T c) is found to be ~3.6 K and the density of critical current is jc ~8MA/cm2. In the work it is experimentally determined that the irradiation of NbN films by composite ion beams leads to the controlled modification of its superconducting properties due to the process of selective substitution of nitrogen atoms on the oxygen atoms.  
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  Notes Approved no  
  Call Number Serial 1000  
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Author Maslennikov, S. url  openurl
  Title RF heating efficiency of the terahertz superconducting hot-electron bolometer Type Journal Article
  Year 2014 Publication arXiv Abbreviated Journal arXiv  
  Volume 1404.5276 Issue Pages 1-4  
  Keywords (down) superconducting hot-electron bolometer mixer, HEB, NbN, distributed model, HEB model, HEB mixer model, heat balance equa-tions, conversion gain, RF heating efficiency, noise temperature, simulation, Euler method  
  Abstract We report results of the numerical solution by the Euler method of the system of heat balance equations written in recurrent form for the superconducting hot-electron bolometer (HEB) embedded in an electrical circuit. By taking into account the dependence of the HEB resistance on the transport current we have been able to calculate rigorously the RF heating efficiency, absorbed local oscillator (LO) power and conversion gain of the HEB mixer. We show that the calculated conversion gai nis in excellent agreement with the experimental results, and that the substitution of the calculated RF heating efficiency and absorbed LO power into the expressions for the conversion gain and noise temperature given by the analytical small-signal model of the HEB yields excellent agreement with the corresponding measured values  
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  Notes Approved no  
  Call Number RPLAB @ atomics90 @ Serial 954  
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Author Glejm, A. V.; Anisimov, A. A.; Asnis, L. N.; Vakhtomin, Yu. B.; Divochiy, A. V.; Egorov, V. I.; Kovalyuk, V. V.; Korneev, A. A.; Kynev, S. M.; Nazarov, Yu. V.; Ozhegov, R. V.; Rupasov, A. V.; Smirnov, K. V.; Smirnov, M. A.; Goltsman, G. N.; Kozlov, S. A. doi  openurl
  Title Quantum key distribution in an optical fiber at distances of up to 200 km and a bit rate of 180 bit/s Type Journal Article
  Year 2014 Publication Bulletin of the Russian Academy of Sciences. Physics Abbreviated Journal  
  Volume 78 Issue 3 Pages 171-175  
  Keywords (down) SSPD, SNSPD, applications  
  Abstract An experimental demonstration of a subcarrier-wave quantum cryptography system with superconducting single-photon detectors (SSPDs) that distributes a secure key in a single-mode fiber at distance of 25 km with a bit rate of 800 kbit/s, a distance of 100 km with a bit rate of 19 kbit/s, and a distance of 200 km with a bit rate of 0.18 kbit/s is described.  
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  ISSN 1062-8738 ISBN Medium  
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  Notes Approved no  
  Call Number RPLAB @ kovalyuk @ Serial 940  
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Author Ozhegov, R.; Elezov, M.; Kurochkin, Y.; Kurochkin, V.; Divochiy, A.; Kovalyuk, V.; Vachtomin, Y.; Smirnov, K.; Goltsman, G. doi  openurl
  Title Quantum key distribution over 300 Type Conference Article
  Year 2014 Publication Proc. SPIE Abbreviated Journal Proc. SPIE  
  Volume 9440 Issue Pages 1F (1 to 9)  
  Keywords (down) SSPD, SNSPD applicatins, quantum key distribution, QKD  
  Abstract We discuss the possibility of polarization state reconstruction and measurement over 302 km by Superconducting Single- Photon Detectors (SSPDs). Because of the excellent characteristics and the possibility to be effectively coupled to singlemode optical fiber many applications of the SSPD have already been reported. The most impressive one is the quantum key distribution (QKD) over 250 km distance. This demonstration shows further possibilities for the improvement of the characteristics of quantum-cryptographic systems such as increasing the bit rate and the quantum channel length, and decreasing the quantum bit error rate (QBER). This improvement is possible because SSPDs have the best characteristics in comparison with other single-photon detectors. We have demonstrated the possibility of polarization state reconstruction and measurement over 302.5 km with superconducting single-photon detectors. The advantage of an autocompensating optical scheme, also known as “plugandplay” for quantum key distribution, is high stability in the presence of distortions along the line. To increase the distance of quantum key distribution with this optical scheme we implement the superconducting single photon detectors (SSPD). At the 5 MHz pulse repetition frequency and the average photon number equal to 0.4 we measured a 33 bit/s quantum key generation for a 101.7 km single mode ber quantum channel. The extremely low SSPD dark count rate allowed us to keep QBER at 1.6% level.  
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  Publisher SPIE Place of Publication Editor Orlikovsky, A. A.  
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  Area Expedition Conference International Conference on Micro- and Nano-Electronics  
  Notes Approved no  
  Call Number RPLAB @ sasha @ ozhegov2014quantum Serial 1048  
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Author Korneeva, Y. P.; Mikhailov, M. Y.; Pershin, Y. P.; Manova, N. N.; Divochiy, A. V.; Vakhtomin, Y. B.; Korneev, A. A.; Smirnov, K. V.; Sivakov, A. G.; Devizenko, A. Y.; Goltsman, G. N. doi  openurl
  Title Superconducting single-photon detector made of MoSi film Type Journal Article
  Year 2014 Publication Supercond. Sci. Technol. Abbreviated Journal Supercond. Sci. Technol.  
  Volume 27 Issue 9 Pages 095012  
  Keywords (down) SSPD, SNSPD  
  Abstract We fabricated and characterized nanowire superconducting single-photon detectors made of 4 nm thick amorphous Mox Si1−x films. At 1.7 K the best devices exhibit a detection efficiency (DE) up to 18% at 1.2 $\mu {\rm m}$ wavelength of unpolarized light, a characteristic response time of about 6 ns and timing jitter of 120 ps. The DE was studied in wavelength range from 650 nm to 2500 nm. At wavelengths below 1200 nm these detectors reach their maximum DE limited by photon absorption in the thin MoSi film.  
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  Publisher IOP Publishing Place of Publication Editor  
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  Series Volume Series Issue Edition  
  ISSN 0953-2048 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number RPLAB @ sasha @ korneeva2014superconducting Serial 1044  
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Author Ozhegov, R. V.; Gorshkov, K. N.; Vachtomin, Y. B.; Smirnov, K. V.; Finkel, M. I.; Goltsman, G. N.; Kiselev, O. S.; Kinev, N. V.; Filippenko, L. V.; Koshelets, V. P. url  doi
openurl 
  Title Terahertz imaging system based on superconducting heterodyne integrated receiver Type Conference Article
  Year 2014 Publication Proc. THz and Security Applications Abbreviated Journal Proc. THz and Security Applications  
  Volume Issue Pages 113-125  
  Keywords (down) SIS mixer, SIR, THz imaging  
  Abstract The development of terahertz imaging instruments for security systems is on the cutting edge of terahertz technology. We are developing a THz imaging system based on a superconducting integrated receiver (SIR). An SIR is a new type of heterodyne receiver based on an SIS mixer integrated with a flux-flow oscillator (FFO) and a harmonic mixer which is used for phase-locking the FFO. Employing an SIR in an imaging system means building an entirely new instrument with many advantages compared to traditional systems.

In this project we propose a prototype THz imaging system using an 1 pixel SIR and 2D scanner. At a local oscillator frequency of 500 GHz the best noise equivalent temperature difference (NETD) of the SIR is 10 mK at an integration time of 1 s and a detection bandwidth of 4 GHz. The scanner consists of two rotating flat mirrors placed in front of the antenna consisting of a spherical primary reflector and an aspherical secondary reflector. The diameter of the primary reflector is 0.3 m. The operating frequency of the imaging system is 600 GHz, the frame rate is 0.1 FPS, the scanning area is 0.5 × 0.5 m2, the image resolution is 50 × 50 pixels, the distance from an object to the scanner was 3 m. We have obtained THz images with a spatial resolution of 8 mm and a NETD of less than 2 K.
 
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  Publisher Springer Netherlands Place of Publication Dordrecht Editor Corsi, C.; Sizov, F.  
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  Series Volume Series Issue Edition  
  ISSN 978-94-017-8828-1 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1368  
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