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Milostnaya, I., Korneev, A., Tarkhov, M., Divochiy, A., Minaeva, O., Seleznev, V., et al. (2008). Superconducting single photon nanowire detectors development for IR and THz applications. J. Low Temp. Phys., 151(1-2), 591–596.
Abstract: We present our progress in the development of superconducting single-photon detectors (SSPDs) based on meander-shaped nanowires made from few-nm-thick superconducting films. The SSPDs are operated at a temperature of 2–4.2 K (well below T c ) being biased with a current very close to the nanowire critical current at the operation temperature. To date, the material of choice for SSPDs is niobium nitride (NbN). Developed NbN SSPDs are capable of single photon counting in the range from VIS to mid-IR (up to 6 μm) with a record low dark counts rate and record-high counting rate. The use of a material with a low transition temperature should shift the detectors sensitivity towards longer wavelengths. We present state-of-the art NbN SSPDs as well as the results of our recent approach to expand the developed SSPD technology by the use of superconducting materials with lower T c , such as molybdenum rhenium (MoRe). MoRe SSPDs first were made and tested; a single photon response was obtained.
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Korneev, A., Divochiy, A., Tarkhov, M., Minaeva, O., Seleznev, V., Kaurova, N., et al. (2008). Superconducting NbN-nanowire single-photon detectors capable of photon number resolving. In Supercond. News Forum.
Abstract: We present our latest generation of ultra-fast superconducting NbN single-photon detectors (SSPD) capable of photon-number resolving (PNR). The novel SSPDs combine 10 μm x 10 μm active area with low kinetic inductance and PNR capability. That resulted in significantly reduced photoresponse pulse duration, allowing for GHz counting rates. The detector’s response magnitude is directly proportional to the number of incident photons, which makes this feature easy to use. We present experimental data on the performance of the PNR SSPDs. These detectors are perfectly suited for fibreless free-space telecommunications, as well as for ultra-fast quantum cryptography and quantum computing.
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Tikhonov, V. V., Polyakova, O. N., Gol’tsman, G. N., Dzardanov, A. L., & Boyarskiy, D. A. (2008). Determination of dielectric properties of ore minerals in the microwave band. Radiophys. Quant. Electron., 51(12), 966–974.
Abstract: We consider a method for determining the complex dielectric permittivity of ore and nonmetal minerals in the microwave band of electromagnetic radiation. The results of measuring the reflectivity and transmittivity of chalcopyrite, magnetite, sphalerite, and labradorite samples in the frequency range 77–300 GHz are presented. A method for calculation of the complex dielectric permittivity of minerals on the basis of the obtained experimental data is proposed. The approximation formulas for calculation of the complex dielectric permittivity of the studied minerals are given.
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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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Polyakova, O. N., Tikhonov, V. V., Dzardanov, A. L., Boyarskii, D. A., & Gol’tsman, G. N. (2008). Dielectric characteristics of ore minerals in a 10–40 GHz frequency range. Tech. Phys. Lett., 34(11), 967–970.
Abstract: A new approach to investigation of the complex dielectric permittivity of both nonmetallic and ore minerals in the microwave frequency range is proposed. Using this approach, data on the complex permittivity of sphalerite, magnetite, and labradorite in a 10–40 GHz frequency range have been obtained for the first time. A method is proposed for calculating the complex permittivity from experimentally measured frequency dependences of the reflection and transmission coefficients of a plane-parallel plate of a given mineral. Approximate expressions that can be used for calculations of the complex refractive index and permittivity of minerals are presented.
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Mohan, N., Minaeva, O., Gol'tsman, G. N., Nasr, M. B., Saleh, B. E., Sergienko, A. V., et al. (2008). Photon-counting optical coherence-domain reflectometry using superconducting single-photon detectors. Opt. Express, 16(22), 18118–18130.
Abstract: We consider the use of single-photon counting detectors in coherence-domain imaging. Detectors operated in this mode exhibit reduced noise, which leads to increased sensitivity for weak light sources and weakly reflecting samples. In particular, we experimentally demonstrate the possibility of using superconducting single-photon detectors (SSPDs) for optical coherence-domain reflectometry (OCDR). These detectors are sensitive over the full spectral range that is useful for carrying out such imaging in biological samples. With counting rates as high as 100 MHz, SSPDs also offer a high rate of data acquisition if the light flux is sufficient.
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Nasr, M. B., Minaeva, O., Goltsman, G. N., Sergienko, A. V., Saleh, B. E., & Teich, M. C. (2008). Submicron axial resolution in an ultrabroadband two-photon interferometer using superconducting single-photon detectors. Opt. Express, 16(19), 15104–15108.
Abstract: We generate ultrabroadband biphotons via the process of spontaneous parametric down-conversion in a quasi-phase-matched nonlinear grating that has a linearly chirped poling period. Using these biphotons in conjunction with superconducting single-photon detectors (SSPDs), we measure the narrowest Hong-Ou-Mandel dip to date in a two-photon interferometer, having a full width at half maximum (FWHM) of approximately 5.7 fsec. This FWHM corresponds to a quantum optical coherence tomography (QOCT) axial resolution of 0.85 µm. Our results indicate that a high flux of nonoverlapping biphotons may be generated, as required in many applications of nonclassical light.
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Sáysz, W., Guziewicz, M., Bar, J., Wegrzecki, M., Grabiec, P., Grodecki, R., et al. (2008). Superconducting NbN nanostructures for single photon quantum detectors. In Proc. 7-th Int. Conf. Ion Implantation and Other Applications of Ions and Electrons (160).
Abstract: Practical quantum systems such as quantum communication (QC) or quantum measurement systems require detectors with high speed, high sensitivity, high quantum efficiency (QE), and short deadtimes along with precise timing characteristics and low dark counts. Superconducting single photon detectors (SSPDs) based on ultrathin meander type NbN nanostripes (operated at T=2-5K) are a new and highly promising type of devices fulfilling above requirements. In this paper we present results of the SSPDs nanostructure technological optimization. The base for our detector is thin-film (4nm) NbN layer deposited on 350- P m-thick sapphire substrate The active element of the detector is a meander- nanostructure made of 4-nm-thick and 100-nm-wide NbN stripe, covering 10 u 10 P m 2 area with the filling factor ~0,5. The NbN superconducting films were deposited on sapphire substrates by DC reactive magnetron sputtering whereas the meander element of the detector was patterned by the direct electron-beam lithography followed by reactive-ion etching. To enhance the SSPD efficiency at Ȝ = 1.55 P m, we have performed an approach to increase the absorption of the detector by integrating it with optical resonant cavity. An optical microcavity optimized for absorption of 1.55 P m photons was designed as an one-mirror resonator consisting of a Ȝ/4 dielectric layer and a metallic mirror. The microcavity was deposited on the top of the NbN SSPD meander. The resonator was formed by the dielectric SiO 2 layer and metal mirror made of gold or palladium. Microcavity layers were deposited using a magnetron sputtering system.
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de Lara, D. P., Ejrnaes, M., Casaburi, A., Lisitskiy, M., Cristiano, R., Pagano, S., et al. (2008). Feasibility investigation of NbN nanowires as detector in time-of-flight mass spectrometers for macromolecules of interest in biology (proteins). J. Low Temp. Phys., 151(3-4), 771–776.
Abstract: We are investigating the possibility of using NbN nanowires as detectors in time-of-flight mass spectrometers for investigation of macromolecules of interest in biology (proteins). NbN nanowires could overcome the two major drawbacks encountered so far by cryogenic detectors, namely the low working temperature in the mK region and the slow temporal response. In fact, NbN nanowires can work at 5 K and the response time is at least a factor 10–100 better than that of other cryogenic detectors. We present a feasibility study based on a numerical code to calculate the response of a NbN nanowire. The parameter space is investigated at different energies from IR to macromolecules (i.e. from eV to keV) in order to understand if larger value of film thickness and width can be used for the keV energy region. We also present preliminary experimental results of irradiation with X-ray photons of NbN to simulate the effect of macromolecules of the same energy.
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Cherednichenko, S., Drakinskiy, V., Lecomte, B., Dauplay, F., Krieg, J. - M., Delorme, Y., et al. (2008). Terahertz heterodyne array based on NbN HEB mixers. In Proc. 19th Int. Symp. Space Terahertz Technol. (43).
Abstract: A 16 pixel heterodyne receiver for 2.5 THz is been developed based on NbN superconducting hot-electron bolometer (HEB) mixers. The receiver uses a quasioptical RF coupling approach where HEB mixers are integrated into double dipole antennas on 1.5μm thick Si3N4 / SiO2 membranes. Miniature mirrors (one per pixel) and back short for the antenna were used to design the output mixer beam profile. The camera design allows all 16 pixel IF readout in parallel. The gain bandwidth of the HEB mixers on Si3N4 / SiO 2 membranes was found to be about 3 GHz, when an MgO buffer layers is applied on the membrane. We will also present the progress in the camera heterodyne tests.
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