Moshkova M, Divochiy A, Morozov P, Vakhtomin Y, Antipov A, Zolotov P, et al. High-performance superconducting photon-number-resolving detectors with 86% system efficiency at telecom range. J Opt Soc Am B. 2019;36(3):B20.
Abstract: The use of improved fabrication technology, highly disordered NbN thin films, and intertwined section topology makes it possible to create high-performance photon-number-resolving superconducting single-photon detectors (PNR SSPDs) that are comparable to conventional single-element SSPDs at the telecom range. The developed four-section PNR SSPD has simultaneously an 86±3% system detection efficiency, 35 cps dark count rate, ∼2 ns dead time, and maximum 90 ps jitter. An investigation of the PNR SSPD’s detection efficiency for multiphoton events shows good uniformity across sections. As a result, such a PNR SSPD is a good candidate for retrieving the photon statistics for light sources and quantum key distribution systems.
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Zolotov P, Divochiy A, Vakhtomin Y, Moshkova M, Morozov P, Seleznev V, et al. Photon-number-resolving SSPDs with system detection efficiency over 50% at telecom range. In: Proc. AIP Conf. Vol 1936.; 2018. 020019.
Abstract: We used technology of making high-efficiency superconducting single-photon detectors as a basis for improvement of photon-number-resolving devices. By adding optical cavity and using an improved NbN superconducting film, we enhanced previously reported system detection efficiency at telecom range for such detectors. Our results show that implementation of optical cavity helps to develop four-section device with quantum efficiency over 50% at 1.55 µm. Performed experimental studies of detecting multi-photon optical pulses showed irregularities over defining multi-photon through single-photon quantum efficiency.
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Sobolewski R, Xu Y, Zheng X, Williams C, Zhang J, Verevkin A, et al. Spectral sensitivity of the NbN single-photon superconducting detector. IEICE Trans Electron. 2002;E85-C(3):797–802.
Abstract: We report our studies on the spectral sensitivity of superconducting NbN thin-film single-photon detectors (SPD's) capable of GHz counting rates of visible and near-infrared photons. In particular, it has been shown that a NbN SPD is sensitive to 1.55-µm wavelength radiation and can be used for quantum communication. Our SPD's exhibit experimentally measured intrinsic quantum efficiencies from 20% at 800 nm up to 1% at 1.55-µm wavelength. The devices demonstrate picosecond response time (<100 ps, limited by our readout system) and negligibly low dark counts. Spectral dependencies of photon counting of continuous-wave, 0.4-µm to 3.5-µm radiation, and 0.63-µm, 1.33-µm, and 1.55-µm laser-pulsed radiations are presented for the single-stripe-type and meander-type devices.
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Корнеев АА, Минаева О, Рубцова И, Милостная И, Чулкова Г, Воронов Б, et al. Сверхпроводящий однофотонный детектор на основе ультратонкой пленки NbN. Квантовая электроника. 2005;35(8):698–700.
Abstract: Представлены результаты исследований сверхпроводящих однофотонных детекторов, изготовленных из ультратонкой пленки NbN. Развитие технологического процесса изготовления детекторов, а также снижение рабочей температуры до 2 К позволили существенно увеличить квантовую эффективность: для видимого света (λ = 0.56 мкм) она составила 30%–40%, т.е. достигла предела, определяемого коэффициентом поглощения пленки. С ростом длины волны квантовая эффективность экспоненциально падает, составляя ~20% на λ=1.55 мкм и ~0.02% на λ = 5 мкм. При скорости темнового счета ~10-4s-1 экспериментально измеренная эквивалентная мощность шума составила 1.5 × 10-20 Вт/Гц-1/2; в дальнейшем она может быть уменьшена до рекордно низкого значения 5 × 10-21 Вт/Гц-1/2. Временное разрешение детектора равно 30 пс.
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Korneev A, Minaeva O, Rubtsova I, Milostnaya I, Chulkova G, Voronov B, et al. Superconducting single-photon ultrathin NbN film detector. Quantum Electronics. 2005;35(8):698–700.
Abstract: Superconducting single-photon ultrathin NbN film detectors are studied. The development of manufacturing technology of detectors and the reduction of their operating temperature down to 2 K resulted in a considerable increase in their quantum efficiency, which reached in the visible region (at 0.56 μm) 30%—40%, i.e., achieved the limit determined by the absorption coefficient of the film. The quantum efficiency exponentially decreases with increasing wavelength, being equal to ~20% at 1.55 μm and ~0.02% at 5 μm. For the dark count rate of ~10-4s-1, the experimental equivalent noise power was 1.5×10-20 W Hz-1/2; it can be decreased in the future down to the record low value of 5×10-21 W Hz-1/2. The time resolution of the detector is 30 ps.
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