Smirnov, K. V., Vachtomin, Y. B., Ozhegov, R. V., Pentin, I. V., Slivinskaya, E. V., Korneev, A. A., et al. (2008). Fiber coupled single photon receivers based on superconducting detectors for quantum communications and quantum cryptography. In P. Tománek, D. Senderáková, & M. Hrabovský (Eds.), Proc. SPIE (Vol. 7138, 713827 (1 to 6)). Spie.
Abstract: At present superconducting detectors become increasingly attractive for various practical applications. In this paper we present results on the depelopment of fiber coupled receiver systems for the registration of IR single photons, optimized for telecommunication and quantum-cryptography. These receiver systems were developed on the basis of superconducting single photon detectors (SSPD) of VIS and IR wavelength ranges. The core of the SSPD is a narrow ( 100 nm) and long ( 0,5 mm) strip in the form of a meander which is patterned from a 4-nm-thick NbN film (TC=10-11 K, jC= 5-7•106 A/cm2); the sensitive area dimensions are 10×10 μm2. The main problem to be solved while the receiver system development was optical coupling of a single-mode fiber (9 microns in diameter) with the SSPD sensitive area. Characteristics of the developed system at the optical input are as follows: quantum efficiency >10 % (at 1.3 μm), >4 % (at 1.55 μm); dark counts rate ≤1 s-1; duration of voltage pulse ≤5 ns; jitter ≤40 ps. The receiver systems have either one or two identical channels (for the case of carrying out correlation measurements) and are made as an insert in a helium storage Dewar.
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Okunev, O., Chulkova, G., Milostnaya, I., Antipov, A., Smirnov, K., Morozov, D., et al. (2008). Registration of infrared single photons by a two-channel receiver based on fiber-coupled superconducting single-photon detectors. In I. A. Sukhoivanov, V. A. Svich, & Y. S. Shmaliy (Eds.), Proc. SPIE (Vol. 7009, 70090V (1 to 8)). SPIE.
Abstract: Single-photon detectors (SPDs) are the foundation of all quantum communications (QC) protocols. Among different classes of SPDs currently studied, NbN superconducting SPDs (SSPDs) are established as the best devices for ultrafast counting of single photons in the infrared (IR) wavelength range. The SSPDs are nanostructured, 100 μm2 in total area, superconducting meanders, patterned by electron lithography in ultra-thin NbN films. Their operation has been explained within a phenomenological hot-electron photoresponse model. We present the design and performance of a novel, two-channel SPD receiver, based on two fiber-coupled NbN SSPDs. The receivers have been developed for fiber-based QC systems, operational at 1.3 μm and 1.55 μm telecommunication wavelengths. They operate in the temperature range from 4.2 K to 2 K, in which the NbN SSPDs exhibit their best performance. The receiver unit has been designed as a cryostat insert, placed inside a standard liquid-heliumstorage dewar. The input of the receiver consists of a pair of single-mode optical fibers, equipped with the standard FC connectors and kept at room temperature. Coupling between the SSPD and the fiber is achieved using a specially designed, precise micromechanical holder that places the fiber directly on top of the SSPD nanostructure. Our receivers achieve the quantum efficiency of up to 7% for near-IR photons, with the coupling efficiency of about 30%. The response time was measured to be < 1.5 ns and it was limited by our read-out electronics. The jitter of fiber-coupled SSPDs is < 35 ps and their dark-count rate is below 1s-1. The presented performance parameters show that our single-photon receivers are fully applicable for quantum correlation-type QC systems, including practical quantum cryptography.
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Slysz, W., Wegrzecki, M., Bar, J., Grabiec, P., Gorska, M., Rieger, E., et al. (2007). Fiber-coupled NbN superconducting single-photon detectors for quantum correlation measurements. In M. Dusek, M. S. Hillery, W. P. Schleich, I. Prochazka, A. L. Migdall, & A. Pauchard (Eds.), Proc. SPIE (Vol. 6583, 65830J (1 to 11)). Spie.
Abstract: We have fabricated fiber-coupled superconducting single-photon detectors (SSPDs), designed for quantum-correlationtype experiments. The SSPDs are nanostructured ( 100-nm wide and 4-nm thick) NbN superconducting meandering stripes, operated in the 2 to 4.2 K temperature range, and known for ultrafast and efficient detection of visible to nearinfrared photons with almost negligible dark counts. Our latest devices are pigtailed structures with coupling between the SSPD structure and a single-mode optical fiber achieved using a micromechanical photoresist ring placed directly over the meander. The above arrangement withstands repetitive thermal cycling between liquid helium and room temperature, and we can reach the coupling efficiency of up to 33%. The system quantum efficiency, measured as the ratio of the photons counted by SSPD to the total number of photons coupled into the fiber, in our early devices was found to be around 0.3 % and 1% for 1.55 &mgr;m and 0.9 &mgr;m photon wavelengths, respectively. The photon counting rate exceeded 250 MHz. The receiver with two SSPDs, each individually biased, was placed inside a transport, 60-liter liquid helium Dewar, assuring uninterrupted operation for over 2 months. Since the receiver’s optical and electrical connections are at room temperature, the set-up is suitable for any applications, where single-photon counting capability and fast count rates are desired. In our case, it was implemented for photon correlation experiments. The receiver response time, measured as a second-order photon cross-correlation function, was found to be below 400 ps, with timing jitter of less than 40 ps.
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Milostnaya, I., Korneev, A., Minaeva, O., Rubtsova, I., Slepneva, S., Seleznev, V., et al. (2005). Superconducting nanostructured detectors capable of single photon counting of mid-infrared optical radiation. In A. Rogalski, E. L. Dereniak, & F. F. Sizov (Eds.), Proc. SPIE (Vol. 5957, 59570A (1 to 9)). SPIE.
Abstract: We report on our progress in research and development of ultrafast superconducting single-photon detectors (SSPDs) based on ultrathin NbN nanostructures. Our SSPDs were made of the 4-nm-thick NbN films with Tc 11 K, patterned as meander-shaped, 100-nm-wide strips, and covering an area of 10×10 μm2. The detectors exploit a combined detection mechanism, where upon a single-photon absorption, a hotspot of excited electrons and redistribution of the biasing supercurrent, jointly produce a picosecond voltage transient signal across the superconducting nanostripe. The SSPDs are typically operated at 4.2 K, but their sensitivity in the infrared radiation range can be significantly improved by lowering the operating temperature from 4.2 K to 2 K. When operated at 2 K, the SSPD quantum efficiency (QE) for visible light photons reaches 30-40%, which is the saturation value limited by the optical absorption of our 4-nm-thick NbN film. With the wavelength increase of the incident photons,the QE of SSPDs decreases significantly, but even at the wavelength of 6 μm, the detector is able to count single photons and exhibits QE of about 10-2 %. The dark (false) count rate at 2 K is as low as 2x10-4 s,-1 which makes our detector essentially a background-limited sensor. The very low dark-count rate results in a noise equivalent power (NEP) below 10-18 WHz-1/2 for the mid-infrared range (6 μm). Further improvement of the SSPD performance in the mid-infrared range can be obtained by substituting NbN for another, lower-Tc materials with a narrow superconducting gap and low quasiparticles diffusivity. The use of such superconductors should shift the cutoff wavelength below 10 μm.
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Slysz, W., Wegrzecki, M., Bar, J., Grabiec, P., Górska, M., Latta, C., et al. (2005). Fiber-coupled quantum-communications receiver based on two NbN superconducting single-photon detectors. In A. Rogalski, E. L. Dereniak, & F. F. Sizov (Eds.), Proc. SPIE (Vol. 5957, 59571K (1 to 10)). SPIE.
Abstract: We present the design and performance of a novel, two-channel single-photon receiver, based on two fiber-coupled NbN superconducting single-photon detectors (SSPDs). The SSPDs are nanostructured superconducting meanders covering an area of 100 μm2 and are known for ultrafast and efficient counting of single, visible-to-infrared photons. Their operation has been explained within a phenomenological hot-electron photoresponse model. Our receiver is intended for fiber-based quantum cryptography and communication systems, operational at near-infrared (NIR) telecommunication wavelengths, λ = 1.3 μm and λ = 1.55 μm. Coupling between the NbN detector and a single-mode optical fiber was achieved using a specially designed, micromechanical photoresist ring, positioned directly over the SSPD active area. The positioning accuracy of the ring was below 1 μm. The receiver with SSPDs was placed (immersed) in a standard liquid-helium transport Dewar and kept without interruption for over two months at 4.2 K. At the same time, the optical fiber inputs and electrical outputs were kept at room temperature. Our best system reached a system quantum efficiency of up to 0.3 % in the NIR radiation range, with the detector coupling efficiency of about 30 %. The response time was measured to be about 250 ps and was limited by our read-out electronics. The measured jitter was close to 35 ps. The presented performance parameters show that our NIR single photon detectors are suitable for practical quantum cryptography and for applications in quantum-correlation experiments.
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Verevkin, A. A., Pearlman, A., Slysz, W., Zhang, J., Sobolewski, R., Chulkova, G., et al. (2003). Ultrafast superconducting single-photon detectors for infrared wavelength quantum communications. In E. Donkor, A. R. Pirich, & H. E. Brandt (Eds.), Proc. SPIE (Vol. 5105, pp. 160–170). SPIE.
Abstract: We have developed a new class of superconducting single-photon detectors (SSPDs) for ultrafast counting of infrared (IR) photons for secure quantum communications. The devices are operated on the quantum detection mechanism, based on the photon-induced hotspot formation and subsequent appearance of a transient resistive barrier across an ultrathin and submicron-wide superconducting stripe. The detectors are fabricated from 3.5-nm-thick NbN films and they operate at 4.2 K inside a closed-cycle refrigerator or liquid helium cryostat. Various continuous and pulsed laser sources have been used in our experiments, enabling us to determine the detector experimental quantum efficiency (QE) in the photon-counting mode, response time, time jitter, and dark counts. Our 3.5-nm-thick SSPDs reached QE above 15% for visible light photons and 5% at 1.3 – 1.5 μm infrared range. The measured real-time counting rate was above 2 GHz and was limited by the read-out electronics (intrinsic response time is <30 ps). The measured jitter was <18 ps, and the dark counting rate was <0.01 per second. The measured noise equivalent power (NEP) is 2 x 10-18 W/Hz1/2 at λ = 1.3 μm. In near-infrared range, in terms of the counting rate, jitter, dark counts, and overall sensitivity, the NbN SSPDs significantly outperform their semiconductor counterparts. An ultrafast quantum cryptography communication technology based on SSPDs is proposed and discussed.
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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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Danerud, M., Winkler, D., Zorin, M., Trifonov, V., Karasik, B., Gershenzon, E. M., et al. (1993). Picosecond detection of infrared radiation with YBa2Cu3O7-δ thin films. In J. R. Birch, & T. J. Parker (Eds.), Proc. SPIE (Vol. 2104, pp. 183–184). Spie.
Abstract: Picosecond nonequilibrium and slow bolometric responses from a patterned high-Tc superconducting (HTS) film due toinfrared radiation were investigated using both modulation and pulse techniques. Measurements at A, = 0.85 [tm andA, = 10.6 lim have shown a similar behaviour of the response vs modulation frequency f. The responsivity of the HTS filmbased detector at f ..- 0.6-1 GHz is estimated to be 10-2 – 10-1 V/W.
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Cherednichenko, S., Drakinskiy, V., Berg, T., Khosropanah, P., & Kollberg, E. (2008). Hot-electron bolometer terahertz mixers for the Herschel Space Observatory. Rev. Sci. Instrum., 79, 034501.
Abstract: We report on low noise terahertz mixers(1.4–1.9THz) developed for the heterodyne spectrometer onboard the Herschel Space Observatory. The mixers employ double slot antenna integrated superconducting hot-electron bolometers (HEBs) made of thin NbN films. The mixer performance was characterized in terms of detection sensitivity across the entire rf band by using a Fourier transform spectrometer (from 0.5to2.5THz, with 30GHz resolution) and also by measuring the mixernoise temperature at a limited number of discrete frequencies. The lowest mixernoise temperature recorded was 750K [double sideband (DSB)] at 1.6THz and 950KDSB at 1.9THz local oscillator (LO) frequencies. Averaged across the intermediate frequency band of 2.4–4.8GHz, the mixernoise temperature was 1100KDSB at 1.6THz and 1450KDSB at 1.9THz LO frequencies. The HEB heterodyne receiver stability has been analyzed and compared to the HEB stability in the direct detection mode. The optimal local oscillator power was determined and found to be in a 200–500nW range.
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Vystavkin, A. N. (1999). Estimation of noise equivalent power and design analysis of an andreev reflection hot-electron microbolometer for submillimeter radioastronomy. Rus. J. Radio Electron., (10).
Abstract: Results of theoretical estimations and measurements of characteristics of an Andreev reflection hot-electron microbolometer for submillimeter radioastronomy made by different researchers are reviewed and analysed. Peculiarities and characteristics of the microbolometers using two types of microthermometer for measurement of the electron temperature increment under influence of the radiation: the SIN-junction and the transition-edge sensor (TES) with electrothermal feedback – are compared. Advantages of the microbolometer with the second type of the microthermometer when the TES is used simultaneously as the absorber of radiation are shown. Methods of achievement of the best noise equivalent power of the microbolometer in such version as well as methods of the matching the microbolometer with the incident radiation flow using planar antennas and with the channel of output signal measurement using a SQUID-picoammeter are considered.
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Semenov, A. V., Devyatov, I. A., Ryabchun, S. A., Maslennikov, S. N., Maslennikova, A. S., Larionov, P. A., et al. (2011). Absorption of terahertz electromagnetic radiation in dirty superconducting film at arbitrary type of the spectral functions. Rus. J. Radio Electron., (10).
Abstract: A problem of absorption of high-frequency electromagnetic field in dirty superconductor is treated within Keldysh technic. Expression for the source term in the kinetic equation for quasiparticle distribution function is derived. The result is significant for deriving a consistent microscopic theory of superconducting detectors for terahertz frequency range, perspective detectors on kinetic inductance of current-biased superconducting strip and on Josephson inductance of tunnel.
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Fedorov, G. E., Stepanova, T. S., Gazaliev, A. S., Gaiduchenko, I. A., Kaurova, N. S., Voronov, B. M., et al. (2016). Asymmetric devices based on carbon nanotubes for terahertz-range radiation detection. Semicond., 50(12), 1600–1603.
Abstract: Various asymmetric detecting devices based on carbon nanotubes (CNTs) are studied. The asymmetry is understood as inhomogeneous properties along the conducting channel. In the first type of devices, an inhomogeneous morphology of the CNT grid is used. In the second type of devices, metals with highly varying work functions are used as the contact material. The relation between the sensitivity and detector configuration is analyzed. Based on the data obtained, approaches to the development of an efficient detector of terahertz radiation, based on carbon nanotubes are proposed.
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Akhmadishina, K. F., Bobrinetskiy, I. I., Komarov, I. A., Malovichko, A. M., Nevolin, V. K., Fedorov, G. E., et al. (2015). Fast-response biological sensors based on single-layer carbon nanotubes modified with specific aptamers. Semicond., 49(13), 1749–1753.
Abstract: The possibility of the fabrication of a fast-response biological sensor based on a composite of single-layer carbon nanotubes and aptamers for the specific detection of proteins is shown. The effect of modification of the surface of the carbon nanotubes on the selectivity and sensitivity of the sensors is investigated. It is shown that carboxylated nanotubes have a better selectivity for detecting thrombin.
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Lieberzeit, P., Afzal, A., Rehman, A., & Dickert, F. (2007). Nanoparticles for detecting pollutants and degradation processes with mass-sensitive sensors. Sensors and Actuators B: Chemical, 127(1), 132–136.
Abstract: Compared with thin films, nanoparticle layers as coatings for QCM offer substantially increased interaction areas and sensitivities with favourable response times. Molybdenum disulphide (MoS2), e.g. has turned out to be a highly suitable material for interacting with thiols. The resulting materials are sufficiently soft according to Pearson to bind sulphur containing compounds reversibly. Depositing MoS2 nanoparticle submonolayers (particle size 200–300 nm) leads to an increase in sensor response by a factor of ten compared to a pure gold layer. Additionally, the nanoparticle layers show fully reversible sensor signals. Particle synthesis can also be combined with the molecular imprinting approach: by a precipitation technique, it is possible to generate molecularly imprinted TiO2 particles for engine oil degradation measurements. Compared with deposited thin layers, particles incorporate oxidised compounds from lubricants by a factor of two better.
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Bespalov, A. V., Gol'tsman, G. N., Semenov, A. D., & Renk, K. F. (1991). Determination of the far-infrared emission characteristic of a cyclotron p-germanium laser by use of a superconducting Nb detector. Solid State Communications, 80(7), 503–506.
Abstract: We studied the far-infrared emission characteristics of a cyclotron p-germanium laser using a broad-band superconducting Nb film detector. For magnetic fields between ∼25 kOe and ∼50 kOe, emission in a frequency range from ∼50 cm-1 to ∼100 cm-1 with maximum intensity around 90 cm-1 was obtained. We determined, for fixed magnetic fields, electric field dependences of the emission intensity taking into account that the total electric field is a sum of the applied and the Hall electric field. An analysis of the emission intensity characteristic gives evidence that transitions between the two lowest Landau levels of light holes are responsible for the laser action.
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