Ryabchun, S., Korneev, A., Matvienko, V., Smirnov, K., Kouminov, P., Seleznev, V., et al. (2004). Superconducting single photon detectors array based on hot electron phenomena. In Proc. 15th Int. Symp. Space Terahertz Technol. (pp. 242–247).
Abstract: In this paper we propose to use time domain multiplexing for large format arrays of superconducting single photon detectors (SSPDs) of the terahertz, visible and infrared frequency ranges based on ultrathin superconducting NbN films. Effective realization of time domain multiplexing for SSPD arrays is possible due to a short electric pulse of the SSPD as response to radiation quantum absorption, picosecond jitter and extremely low noise equivalent power (NEP). We present experimental results of testing 2×2 arrays in the infrared waveband. The measured noise equivalent power in the infrared and expected for the terahertz waveband is 10 – 21 WHz -1/2 . The best quantum efficiency (QE) of SSPD is 50% at 1.3 µm wavelength.
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Goltsman, G., Korneev, A., Izbenko, V., Smirnov, K., Kouminov, P., Voronov, B., et al. (2004). Nano-structured superconducting single-photon detectors. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 520(1-3), 527–529.
Abstract: NbN detectors, formed into meander-type, 10×10-μm2 area structures, based on ultrathin (down to 3.5-nm thickness) and nanometer-width (down to below 100 nm) NbN films are capable of efficiently detecting and counting single photons from the ultraviolet to near-infrared optical wavelength range. Our best devices exhibit QE >15% in the visible range and ∼10% in the 1.3–1.5-μm infrared telecommunication window. The noise equivalent power (NEP) ranges from ∼10−17 W/Hz1/2 at 1.5 μm radiation to ∼10−19 W/Hz1/2 at 0.56 μm, and the dark counts are over two orders of magnitude lower than in any semiconducting competitors. The intrinsic response time is estimated to be <30 ps. Such ultrafast detector response enables a very high, GHz-rate real-time counting of single photons. Already established applications of NbN photon counters are non-invasive testing and debugging of VLSI Si CMOS circuits and quantum communications.
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Rubtsova, I., Korneev, A., Matvienko, V., Chulkova, G., Milostnaya, I., Goltsman, G., et al. (2004). Spectral sensitivity, quantum efficiency, and noise equivalent power of NbN superconducting single-photon detectors in the IR range. In Proc. 29th IRMMW / 12th THz (pp. 461–462).
Abstract: We have developed nanostructured NbN superconducting single-photon detectors capable of GHz-rate photon counting in the 0.4 to 5 /spl mu/m wavelength range. Quantum efficiency of 30%, dark count rate 3/spl times/10/sup -4/ s/sup -1/, and NEP=10/sup -20/ W/Hz/sup -1/2/ have been measured at the 1.3-/spl mu/m wavelength for the device operating at 2.0 K.
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Verevkin, A., Zhang, J., Pearlman, A., Slysz, W., Sobolewski, R., Korneev, A., et al. (2004). Ultimate sensitivity of superconducting single-photon detectors in the visible to infrared range.
Abstract: We present our quantum efficiency (QE) and noise equivalent power (NEP) measurements of the meandertype ultrathin NbN superconducting single-photon detector in the visible to infrared radiation range. The nanostructured devices with 3.5-nm film thickness demonstrate QE up to~ 10% at 1.3–1.55 µm wavelength, and up to 20% in the entire visible range. The detectors are sensitive to infrared radiation with the wavelengths down to~ 10 µm. NEP of about 2× 10-18 W/Hz1/2 was obtained at 1.3 µm wavelength. Such high sensitivity together with GHz-range counting speed, make NbN photon counters very promising for efficient, ultrafast quantum communications and another applications. We discuss the origin of dark counts in our devices and their ultimate sensitivity in terms of the resistive fluctuations in our superconducting nanostructured devices.
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Sobolewski, R., Verevkin, A., Gol'tsman, G. N., Lipatov, A., & Wilsher, K. (2003). Ultrafast superconducting single-photon optical detectors and their applications. IEEE Trans. Appl. Supercond., 13(2), 1151–1157.
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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