Ekstrom, H., Karasik, B., Weikle, R., Yngvesson, K. S., Gol’tsman, G., Kollberg, E., et al. (1993). Mixers using superconducting Nb films in the resistive state. In 23rd European Microwave Conf. (pp. 787–789).
Abstract: The mixing of 20 GHz radiation in a Nb superconducting film in the resistive state was studied. The experiment gave evidence of electron-heating to be the origin of the non-linear phenomenon. The requirements on the operation mode and on the film parameters in order to obtain small conversion losses or even gain are determined. Our measurements indicate a conversion loss of about 6-8 dB. The hot-electron bolometer is considered to be very promising for use in heterodyne receivers in a wide frequency range from microwaves to terahertz frequencies.
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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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Fiore, A., Marsili, F., Bitauld, D., Gaggero, A., Leoni, R., Mattioli, F., et al. (2009). Counting photons using a nanonetwork of superconducting wires. In M. Cheng (Ed.), Nano-Net (pp. 120–122). Berlin, Heidelberg: Springer Berlin Heidelberg.
Abstract: We show how the parallel connection of photo-sensitive superconducting nanowires can be used to count the number of photons in an optical pulse, down to the single-photon level. Using this principle we demonstrate photon-number resolving detectors with unprecedented sensitivity and speed at telecommunication wavelengths.
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Korneev, A., Semenov, A., Vodolazov, D., Gol’tsman, G. N., & Sobolewski, R. (2017). Physics and operation of superconducting single-photon devices. In R. Wördenweber, V. Moshchalkov, S. Bending, & F. Tafuri (Eds.), Superconductors at the Nanoscale (pp. 279–308). De Gruyter.
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Arutyunov, K. Y., Ramos-Álvarez, A., Semenov, A. V., Korneeva, Y. P., An, P. P., Korneev, A. A., et al. (2016). Quasi-1-dimensional superconductivity in highly disordered NbN nanowires. arXiv:1602.07932v1 [cond-mat.supr-con].
Abstract: The topic of superconductivity in strongly disordered materials has attracted a significant attention. In particular vivid debates are related to the subject of intrinsic spatial inhomogeneity responsible for non-BCS relation between the superconducting gap and the pairing potential. Here we report experimental study of electron transport properties of narrow NbN nanowires with effective cross sections of the order of the debated inhomogeneity scales. We find that conventional models based on phase slip concept provide reasonable fits for the shape of the R(T) transition curve. Temperature dependence of the critical current follows the text-book Ginzburg-Landau prediction for quasi-one-dimensional superconducting channel Ic~(1-T/Tc)^3/2. Hence, one may conclude that the intrinsic electronic inhomogeneity either does not exist in our structures, or, if exist, does not affect their resistive state properties.
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