Verevkin, A., Slysz, W., Pearlman, A., Zhang, J., Sobolewski, R., Okunev, O., et al. (2003). Real-time GHz-rate counting of infrared photons using nanostructured NbN superconducting detectors. In CLEO/QELS (CThM8). Optical Society of America.
Abstract: We demonstrate that our ultrathin, nanometer-width NbN superconducting single-photon detectors are capable of above 1-GHz-frequency, real-time counting of near-infrared photons. The measured system jitter of the detector is below 15 ps.
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Verevkin, A., Williams, C., Gol’tsman, G. N., Sobolewski, R., & Gilbert, G. (2001). Single-photon superconducting detectors for practical high-speed quantum cryptography. Optical Society of America.
Abstract: We have developed an ultrafast superconducting single-photon detector with negligible dark counting rate. The detector is based on an ultrathin, submicron-wide NbN meander-type stripe and can detect individual photons in the visible to near-infrared wavelength range at a rate of at least 10 Gb/s. The above counting rate allows us to implement the NbN device to unconditionally secret quantum key distRochester, New Yorkribution in a practical, high-speed system using real-time Vernam enciphering.
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Ozhegov, R. V., Okunev, O. V., Gol’tsman, G. N., Filippenko, L. V., & Koshelets, V. P. (2009). Noise equivalent temperature difference of a superconducting integrated terahertz receiver. J. Commun. Technol. Electron., 54(6), 716–720.
Abstract: The dependence of the noise equivalent temperature difference (NETD) of a superconducting integrated receiver (SIR) on the receiver noise temperature and the inputsignal level has been investigated. An unprecedented NETD of 13±2 mK has been measured at a SIR noise temperature of 200 K, intermediate-frequency bandwidth of 4 GHz, and time constant of 1 s. With a decrease in the input signal, an improvement in the NETD is observed. This effect is explained by a reduction in the influence of the instabilities of the receiver power supply and the amplification circuit that occur when the input signal is decreased.
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Beck, M., Klammer, M., Lang, S., Leiderer, P., Kabanov, V. V., Gol’tsman, G. N., et al. (2011). Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy. arXiv:1102.5616v2 [cond-mat.supr-con].
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, \lambda = 1.1 +/- 0.1, which is in excellent agreement with theoretical estimates.
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Tret’yakov, I. V., Ryabchun, S. A., Kaurova, N. S., Larionov, P. A., Lobastova, A. A., Voronov, B. M., et al. (2010). Optimum absorbed heterodyne power for superconducting NbN hot-electron bolometer mixer. Tech. Phys. Lett., 36(12), 1103–1105.
Abstract: Absorbed heterodyne power has been measured in a low-noise broadband hot-electron bolometer (HEB) mixer for the terahertz range, operating on the effect of electron heating in the resistive state of an ultrathin superconducting NbN film. It is established that the optimum absorbed heterodyne power for the HEB mixer operating at 2.5 THz is about 100 nW.
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