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Heeres RW, Dorenbos SN, Koene B, Solomon GS, Kouwenhoven LP, Zwiller V. On-Chip Single Plasmon Detection. Nano Lett. 2010;10:661–4.
Abstract: Surface plasmon polaritons (plasmons) have the potential to interface electronic and optical devices. They could prove extremely useful for integrated quantum information processing. Here we demonstrate on-chip electrical detection of single plasmons propagating along gold waveguides. The plasmons are excited using the single-photon emission of an optically emitting quantum dot. After propagating for several micrometers, the plasmons are coupled to a superconducting detector in the near-field. Correlation measurements prove that single plasmons are being detected.
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Sobolewski R, Verevkin A, Gol'tsman GN, Lipatov A, Wilsher K. Ultrafast superconducting single-photon optical detectors and their applications. IEEE Trans. Appl. Supercond.. 2003;13(2):1151–7.
Abstract: We present a new class of ultrafast single-photon detectors for counting both visible and infrared photons. The detection mechanism is based on photon-induced hotspot formation, which forces the supercurrent redistribution and leads to the appearance of a transient resistive barrier across an ultrathin, submicrometer-width, superconducting stripe. The devices were fabricated from 3.5-nm- and 10-nm-thick NbN films, patterned into <200-nm-wide stripes in the 4 /spl times/ 4-/spl mu/m/sup 2/ or 10 /spl times/ 10-/spl mu/m/sup 2/ meander-type geometry, and operated at 4.2 K, well below the NbN critical temperature (T/sub c/=10-11 K). Continuous-wave and pulsed-laser optical sources in the 400-nm-to 3500-nm-wavelength range were used to determine the detector performance in the photon-counting mode. Experimental quantum efficiency was found to exponentially depend on the photon wavelength, and for our best, 3.5-nm-thick, 100-/spl mu/m/sup 2/-area devices varied from >10% for 405-nm radiation to 3.5% for 1550-nm photons. The detector response time and jitter were /spl sim/100 ps and 35 ps, respectively, and were acquisition system limited. The dark counts were below 0.01 per second at optimal biasing. In terms of the counting rate, jitter, and dark counts, the NbN single-photon detectors significantly outperform their semiconductor counterparts. Already-identified applications for our devices range from noncontact testing of semiconductor CMOS VLSI circuits to free-space quantum cryptography and communications.
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Il’in KS, Milostnaya II, Verevkin AA, Gol’tsman GN, Gershenzon EM, Sobolewski R. Ultimate quantum efficiency of a superconducting hot-electron photodetector. Appl Phys Lett. 1998;73(26):3938–40.
Abstract: The quantum efficiency and current and voltage responsivities of fast hot-electron photodetectors, fabricated from superconducting NbN thin films and biased in the resistive state, have been shown to reach values of 340, 220 A/W, and 4×104 V/W,
respectively, for infrared radiation with a wavelength of 0.79 μm. The characteristics of the photodetectors are presented within the general model, based on relaxation processes in the nonequilibrium electron heating of a superconducting thin film. The observed, very high efficiency and sensitivity of the superconductor absorbing the photon are explained by the high multiplication rate of quasiparticles during the avalanche breaking of Cooper pairs.
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Ferrari S, Kovalyuk V, Hartmann W, Vetter A, Kahl O, Lee C, et al. Hot-spot relaxation time current dependence in niobium nitride waveguide-integrated superconducting nanowire single-photon detectors. Opt Express. 2017;25(8):8739–50.
Abstract: We investigate how the bias current affects the hot-spot relaxation dynamics in niobium nitride. We use for this purpose a near-infrared pump-probe technique on a waveguide-integrated superconducting nanowire single-photon detector driven in the two-photon regime. We observe a strong increase in the picosecond relaxation time for higher bias currents. A minimum relaxation time of (22 +/- 1)ps is obtained when applying a bias current of 50% of the switching current at 1.7 K bath temperature. We also propose a practical approach to accurately estimate the photon detection regimes based on the reconstruction of the measured detector tomography at different bias currents and for different illumination conditions.
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Verevkin A, Zhang J, Sobolewski R, Lipatov A, Okunev O, Chulkova G, et al. Detection efficiency of large-active-area NbN single-photon superconducting detectors in the ultraviolet to near-infrared range. Appl. Phys. Lett.. 2002;80(25):4687–9.
Abstract: We report our studies on spectral sensitivity of meander-type, superconducting NbN thin-film single-photon detectors (SPDs), characterized by GHz counting rates of visible and near-infrared photons and negligible dark counts. Our SPDs exhibit experimentally determined quantum efficiencies ranging from ∼0.2% at the 1.55 μm wavelength to ∼70% at 0.4 μm. Spectral dependences of the detection efficiency (DE) at the 0.4 to 3.0-μm-wavelength range are presented. The exponential character of the DE dependence on wavelength, as well as its dependence versus bias current, is qualitatively explained in terms of superconducting fluctuations in our ultrathin, submicron-width superconducting stripes. The DE values of large-active-area NbN SPDs in the visible range are high enough for modern quantum communications.
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