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Palma, F., Teppe, F., Fatimy, A. E., Green, R., Xu, J., Vachontin, Y., et al. (2010). THz communication system based on a THz quantum cascade laser and a hot electron bolometer. In 35th Int. Conf. Infrared, Millimeter, and Terahertz Waves (11623798 (1 to 2)).
Abstract: We present the experimental study of the direct emission – detection system based on the THz Quantum Cascade Laser as a source and Hot Electron Bolometer (HEB) detector – in view of its application as an optical communication system. We show that the system can efficiently transmit the QCL Terahertz pulses. We estimate the maximal modulation speed of the system to be about several GHz and show that it is limited only by the QCL pulse power supply, detector amplifier and connection line/wires parameters.
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Beebe, M. R., Beringer, D. B., Burton, M. C., Yang, K., & Lukaszew, R. A. (2016). Stoichiometry and thickness dependence of superconducting properties of niobium nitride thin films. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 34(2), 021510 (1 to 4).
Abstract: The current technology used in linear particle accelerators is based on superconducting radio frequency (SRF) cavities fabricated from bulk niobium (Nb), which have smaller surface resistance and therefore dissipate less energy than traditional nonsuperconducting copper cavities. Using bulk Nb for the cavities has several advantages, which are discussed elsewhere; however, such SRF cavities have a material-dependent accelerating gradient limit. In order to overcome this fundamental limit, a multilayered coating has been proposed using layers of insulating and superconducting material applied to the interior surface of the cavity. The key to this multilayered model is to use superconducting thin films to exploit the potential field enhancement when these films are thinner than their London penetration depth. Such field enhancement has been demonstrated in MgB2 thin films; here, the authors consider films of another type-II superconductor, niobium nitride (NbN). The authors present their work correlating stoichiometry and superconducting properties in NbN thin films and discuss the thickness dependence of their superconducting properties, which is important for their potential use in the proposed multilayer structure. While there are some previous studies on the relationship between stoichiometry and critical temperature TC, the authors are the first to report on the correlation between stoichiometry and the lower critical field HC1.
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Korneev, A., Divochiy, A., Marsili, F., Bitauld, D., Fiore, A., Seleznev, V., et al. (2008). Superconducting photon number resolving counter for near infrared applications. In P. Tománek, D. Senderáková, & M. Hrabovský (Eds.), Proc. SPIE (Vol. 7138, 713828 (1 to 5)). Spie.
Abstract: We present a novel concept of photon number resolving detector based on 120-nm-wide superconducting stripes made of 4-nm-thick NbN film and connected in parallel (PNR-SSPD). The detector consisting of 5 strips demonstrate a capability to resolve up to 4 photons absorbed simultaneously with the single-photon quantum efficiency of 2.5% and negligibly low dark count rate.
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Marsili, F., Bitauld, D., Divochiy, A., Gaggero, A., Leoni, R., Mattioli, F., et al. (2008). Superconducting nanowire photon number resolving detector at telecom wavelength. In CLEO/QELS (Qmj1 (1 to 2)). Optical Society of America.
Abstract: We demonstrate a photon-number-resolving (PNR) detector, based on parallel superconducting nanowires, capable of resolving up to 5 photons in the telecommunication wavelength range, with sensitivity and speed far exceeding existing approaches.
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Korneev, A., Divochiy, A., Tarkhov, M., Minaeva, O., Seleznev, V., Kaurova, N., et al. (2008). New advanced generation of superconducting NbN-nanowire single-photon detectors capable of photon number resolving. In J. Phys.: Conf. Ser. (Vol. 97, 012307 (1 to 6)).
Abstract: We present our latest generation of ultrafast superconducting NbN single-photon detectors (SSPD) capable of photon-number resolving (PNR). We have developed, fabricated and tested a multi-sectional design of NbN nanowire structures. The novel SSPD structures consist of several meander sections connected in parallel, each having a resistor connected in series. The novel SSPDs combine 10 μm × 10 μm active areas with a low kinetic inductance and PNR capability. That resulted in a 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 performances of the PNR SSPDs. The PNR SSPDs are perfectly suited for fibreless free-space telecommunications, as well as for ultrafast quantum cryptography and quantum computing.
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