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Author Marsili, Francesco; Najafi, Faraz; Herder, Charles; Berggren, Karl K.
Title Electrothermal simulation of superconducting nanowire avalanche photodetectors Type Journal Article
Year 2011 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume (up) 98 Issue 9 Pages 3
Keywords SNAP
Abstract We developed an electrothermal model of NbN superconducting nanowire avalanche photodetectors (SNAPs) on sapphire substrates. SNAPs are single-photon detectors consisting of the parallel connection of N superconducting nanowires. We extrapolated the physical constants of the model from experimental data and we simulated the time evolution of the device resistance, temperature and current by solving two coupled electrical and thermal differential equations describing the nanowires. The predictions of the model were in good quantitative agreement with the experimental results.
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Call Number RPLAB @ gujma @ Serial 658
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Author Sprengers, J. P.; Gaggero, A.; Sahin, D.; Jahanmirinejad, S.; Frucci, G.; Mattioli, F.; Leoni, R.; Beetz, J.; Lermer, M.; Kamp, M.; Höfling, S.; Sanjines, R.; Fiore A.
Title Waveguide superconducting single-photon detectors for integrated quantum photonic circuits Type Journal Article
Year 2011 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume (up) 99 Issue 18 Pages 181110(1-3)
Keywords optical waveguides, waveguide SSPD
Abstract The monolithic integration of single-photon sources, passive optical circuits, and single-photon detectors enables complex and scalable quantum photonic integrated circuits, for application in linear-optics quantum computing and quantum communications. Here, we demonstrate a key component of such a circuit, a waveguide single-photon detector. Our detectors, based on superconducting nanowires on GaAs ridge waveguides, provide high efficiency (~0%) at telecom wavelengths, high timing accuracy (~0 ps), and response time in the ns range and are fully compatible with the integration of single-photon sources, passive networks, and modulators.
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Call Number Serial 847
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Author Beck, M.; Klammer, M.; Lang, S.; Leiderer, P.; Kabanov, V. V.; Gol'tsman, G. N.; Demsar, J.
Title Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy Type Journal Article
Year 2011 Publication Phys. Rev. Lett. Abbreviated Journal Phys. Rev. Lett.
Volume (up) 107 Issue 17 Pages 4
Keywords NbN thin film, energy gap dynamics
Abstract Using time-domain terahertz spectroscopy we performed direct studies of the photoinduced suppression and recovery of the superconducting gap in a conventional BCS superconductor NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the bare quasiparticle recombination rate, the Cooper pair-breaking rate and the electron-phonon coupling constant, λ=1.1±0.1, which is in excellent agreement with theoretical estimates.
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Call Number RPLAB @ gujma @ Serial 641
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Author Sprengers, J.P.; Gaggero, A.; Sahin, D.; Nejad, S. Jahanmiri; Mattioli, F.; Leoni, R.; Beetz, J.; Lermer, M.; Kamp, M.; Höfling, S.; Sanjines, R.; Fiore A.
Title Waveguide single-photon detectors for integrated quantum photonic circuits Type Conference Article
Year 2011 Publication arXiv Abbreviated Journal arXiv
Volume (up) 1108.5107 Issue Pages 1-11
Keywords optical waveguides, waveguide SSPD
Abstract The generation, manipulation and detection of quantum bits (qubits) encoded on single photons is at the heart of quantum communication and optical quantum information processing. The combination of single-photon sources, passive optical circuits and single-photon detectors enables quantum repeaters and qubit amplifiers, and also forms the basis of all-optical quantum gates and of linear-optics quantum computing. However, the monolithic integration of sources, waveguides and detectors on the same chip, as needed for scaling to meaningful number of qubits, is very challenging, and previous work on quantum photonic circuits has used external sources and detectors. Here we propose an approach to a fully-integrated quantum photonic circuit on a semiconductor chip, and demonstrate a key component of such circuit, a waveguide single-photon detector. Our detectors, based on superconducting nanowires on GaAs ridge waveguides, provide high efficiency (20%) at telecom wavelengths, high timing accuracy (60 ps), response time in the ns range, and are fully compatible with the integration of single-photon sources, passive networks and modulators.
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Call Number Serial 846
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Author Korneev, Alexander; Korneeva, Yulia; Florya, Irina; Elezov, Michael; Manova, Nadezhda; Tarkhov, Michael; An, Pavel; Kardakova, Anna; Isupova, Anastasiya; Chulkova, Galina; Voronov, Boris
Title Recent advances in superconducting NbN single-photon detector development Type Conference Article
Year 2011 Publication Proc. SPIE Abbreviated Journal Proc. SPIE
Volume (up) 8072 Issue Pages 807202 (1 to 10)
Keywords SSPD
Abstract Superconducting single-photon detector (SSPD) is a planar nanostructure patterned from 4-nm-thick NbN film deposited on sapphire substrate. The sensitive element of the SSPD is 100-nm-wide NbN strip. The device is operated at liquid helium temperature. Absorption of a photon leads to a local suppression of superconductivity producing subnanosecond-long voltage pulse. In infrared (at 1550 nm and longer wavelengths) SSPD outperforms avalanche photodiodes in terms of detection efficiency (DE), dark counts rate, maximum counting rate and timing jitter. Efficient single-mode fibre coupling of the SSPD enabled its usage in many applications ranging from single-photon sources research to quantum cryptography. Recently we managed to improve the SSPD performance and measured 25% detection efficiency at 1550 nm wavelength and dark counts rate of 10 s-1. We also improved photon-number resolving SSPD (PNR-SSPD) which realizes a spatial multiplexing of incident photons enabling resolving of up to 4 simultaneously absorbed photons. Another improvement is the increase of the photon absorption using a λ/4 microcavity integrated with the SSPD. And finally in our strive to increase the DE at longer wavelengths we fabricated SSPD with the strip almost twice narrower compared to the standard 100 nm and demonstrated that in middle infrared (about 3 μm wavelength) these devices have DE several times higher compared to the traditional SSPDs.
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Call Number RPLAB @ gujma @ Serial 663
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