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Author Lusche, Robert; Semenov, Alexey; Huebers, Heinz-Willhelm; Ilin, Konstantin; Siegel, Michael; Korneeva, Yuliya; Trifonov, Andrey; Korneev, Alexander; Goltsman, Gregory
Title (down) Effect of the wire geometry and an externally applied magnetic field on the detection efficiency of superconducting nanowire single-photon detectors Type Abstract
Year 2013 Publication INIS Abbreviated Journal INIS
Volume 46 Issue 8 Pages 1-3
Keywords TaN, NbN SSPD, SNSPD
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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Call Number Serial 1374
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Author Ryabchun, S.; Tong, C.-yu E.; Blundell, R.; Kimberk, R.; Gol’tsman, G.
Title (down) Effect of microwave radiation on the stability of terahertz hot-electron bolometer mixers Type Conference Article
Year 2006 Publication Proc. SPIE Abbreviated Journal Proc. SPIE
Volume 6373 Issue Pages 63730J (1 to 5)
Keywords NbN HEB mixers, hot-electron bolometer mixers, stability, Allan variance, LO power fluctuations
Abstract We report our studies of the effect of microwave radiation, with a frequency much lower than that corresponding to the energy gap of the superconductor, on the performance of the NbN hot-electron bolometer (HEB) mixer incorporated into a THz heterodyne receiver. It is shown that exposing the HEB mixer to microwave radiation does not result in a significant rise of the receiver noise temperature and degradation of the mixer conversion gain so long as the level of microwave power is small compared to the local oscillator drive. Hence the injection of a small, but controlled amount of microwave radiation enables active compensation of local oscillator power and coupling fluctuations which can significantly degrade the stability of HEB mixer receivers.
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Publisher SPIE Place of Publication Editor Anwar, M.; DeMaria, A.J.; Shur, M.S.
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Area Expedition Conference Terahertz Physics, Devices, and Systems
Notes Approved no
Call Number Serial 1441
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Author Lusche, R.; Semenov, A.; Korneeva, Y.; Trifonov, A.; Korneev, A.; Gol'tsman, G.; Hübers, H.-W.
Title (down) Effect of magnetic field on the photon detection in thin superconducting meander structures Type Journal Article
Year 2014 Publication Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 89 Issue 10 Pages 104513 (1 to 7)
Keywords NbN SSPD, SNSPD
Abstract We have studied the influence of an externally applied magnetic field on the photon and dark count rates of meander-type niobium nitride superconducting nanowire single-photon detectors. Measurements have been performed at a temperature of 4.2 K, and magnetic fields up to 250 mT have been applied perpendicularly to the meander plane. While photon count rates are field independent at weak applied fields, they show a strong dependence at fields starting from approximately ±25 mT. This behavior, as well as the magnetic field dependence of the dark count rates, is in good agreement with the recent theoretical model of vortex-assisted photon detection and spontaneous vortex crossing in narrow superconducting lines. However, the local reduction of the superconducting free energy due to photon absorption, which is the fitting parameter in the model, increases much slower with the photon energy than the model predicts. Furthermore, changes in the free-energy during photon counts and dark counts depend differently on the current that flows through the meander. This indicates that photon counts and dark counts occur in different parts of the meander.
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ISSN 1098-0121 ISBN Medium
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Notes Approved no
Call Number Serial 1367
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Author Lobanov, Y.V.; Tong, C.-Y.E.; Hedden, A.S.; Blundell, R.; Voronov, B.M.; Gol'tsman, G.N.
Title (down) Direct measurement of the gain and noise bandwidths of HEB mixers Type Journal Article
Year 2011 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.
Volume 21 Issue 3 Pages 645-648
Keywords waveguide NbN HEB mixers
Abstract The intermediate frequency (IF) bandwidth of a hot electron bolometer (HEB) mixer is an important parameter of the mixer, in that it helps to determine its suitability for a given application. With the availability of wideband low noise amplifiers, it is simple to measure the performance of an HEB mixer over a wide range of IF at a fixed LO frequency using the standard Y-factor method. This in-situ method allows us to measure both the gain and noise bandwidths simultaneously. We have also measured mixer output impedance with a vector network analyser. Intrinsic time constant has been extracted from the impedance data and compared to the mixer's bandwidths determined from receiver Y-factor measurement.
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Notes Approved no
Call Number RPLAB @ gujma @ Serial 720
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Author Rodriguez-Morales, F.; Zannoni, R.; Nicholson, J.; Fischetti, M.; Yngvesson, K. S.; Appenzeller, J.
Title (down) Direct and heterodyne detection of microwaves in a metallic single wall carbon nanotube Type Journal Article
Year 2006 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume 89 Issue 8 Pages 083502
Keywords carbon nanotube, GHz heterodyne detector, direct detector
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ISSN 0003-6951 ISBN Medium
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Notes Approved no
Call Number Serial 565
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