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| Author |
Гольцман, Г. Н.; Веревкин, А. А.; Гершензон, Е. М.; Птицина, Н. Г.; Смирнов, К. В.; Чулкова, Г. М. |
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Исследования процессов неупругой релаксации и примесная спектроскопия-релаксометрия в двумерном электронном газе в полупроводниковых структурах с квантовыми ямами |
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Report |
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1995 |
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В гетероструктурах GaAs/AlGaAs впервые прямым методом измерена температурная зависимость вpемени энеpгетической pелаксации двумерного электронного газа te(T) в широком диапазоне температур Т=1,5 – 50 К в квазиравновесных условиях. Для измерений использовался высокочувствительный спектрометр миллиметрового диапазона волн с высоким временным разрешением, который позволял измерять релаксационные времена до 150 пс с погрешностью не более 20%. Верхний предел температуры определялся временным разрешением спектрометра. Исследования проводились на высококачественных образцах с поверхностной концентрацией носителей ns = 4,2 1011 см-2 и подвижностью m = 7 105 см2В-1с-1 (при Т = 4,2К). В квазиравновесных условиях из температурной зависимости tе определен предел подвижности при низких температурах (T<4.2 K), связанный с рассеянием на пьезоакустическом потенциале, получено время неупругой релаксации, связанное с рассеянием на деформационном потенциале (15 K25 K), получено характерное время испускания оптического фонона (tLO>4,5пс), которое существенно превышает время сронтанного излучения оптического фонона (примерно в 30 раз), что связано с большой ролью процессов перепоглащения фононов электронами.При низких температурах проведены измерения tе в условиях сильного разогрева. Полученные значения tе и зависимость tе от температуры электронов Те совпадают с tе(Т) в квазиравновесных условиях при Т=Те. Из полученных значений tе(Те) построена зависимость мощности энергетических потерь от Те, которая хорошо согласуется с литературными данными.Начаты измерения в магнитном поле, которые показывают переспективность использованного нами метода измерений как в области слабых магнитных полей при факторе заполнения >10, так и в области сильных магнитных полей при факторе заполнения >1-2. |
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Отчет о НИР/НИОКР; РФФИ: 95-02-06409-а; |
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1831 |
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Vasilev, D. D.; Malevannaya, E. I.; Moiseev, K. M.; Zolotov, P. I.; Antipov, A. V.; Vakhtomin, Y. B.; Smirnov, K. V. |
| Title |
Influence of deposited material energy on superconducting properties of the WSi films |
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Conference Article |
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2020 |
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IOP Conf. Ser.: Mater. Sci. Eng. |
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IOP Conf. Ser.: Mater. Sci. Eng. |
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781 |
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012013 (1 to 6) |
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WSi SSPD, SNSPD |
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WSi thin films have the advantages for creating SNSPDs with a large active area or array of detectors on a single substrate due to the amorphous structure. The superconducting properties of ultrathin WSi films substantially depends on their structure and thickness as the NbN films. Scientific groups investigating WSi films mainly focused only on changes of their thickness and the ratio of the components on the substrate at room temperature. This paper presents experiments to determine the effect of the bias potential on the substrate, the temperature of the substrate, and the peak power of pulsed magnetron sputtering, which is the equivalent of ionization, a tungsten target, on the surface resistance and superconducting properties of the WSi ultrathin films. The negative effect of the substrate temperature and the positive effect of the bias potential and the ionization coefficient (peak current) allow one to choose the best WSi films formation mode for SNSPD: substrate temperature 297 K, bias potential -60 V, and peak current 3.5 A. |
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1757-899X |
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1798 |
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Kovalyuk, V.; Ferrari, S.; Kahl, O.; Semenov, A.; Lobanov, Y.; Shcherbatenko, M.; Korneev, A.; Pernice, W.; Goltsman, G. |
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Waveguide integrated superconducting single-photon detector for on-chip quantum and spectral photonic application |
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Conference Article |
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2017 |
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J. Phys.: Conf. Ser. |
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J. Phys.: Conf. Ser. |
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917 |
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062032 |
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SSPD, SNSPD, waveguide |
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With use of the travelling-wave geometry approach, integrated superconductor- nanophotonic devices based on silicon nitride nanophotonic waveguide with a superconducting NbN-nanowire suited on top of the waveguide were fabricated. NbN-nanowire was operated as a single-photon counting detector with up to 92 % on-chip detection efficiency in the coherent mode, serving as a highly sensitive IR heterodyne mixer with spectral resolution (f/df) greater than 106 in C-band at 1550 nm wavelength |
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RPLAB @ kovalyuk @ |
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1140 |
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Kovalyuk, V.; Ferrari, S.; Kahl, O.; Semenov, A.; Shcherbatenko, M.; Lobanov, Y.; Ozhegov, R.; Korneev, A.; Kaurova, N.; Voronov, B.; Pernice, W.; Gol'tsman, G. |
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On-chip coherent detection with quantum limited sensitivity |
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Journal Article |
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2017 |
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Sci Rep |
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Sci Rep |
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7 |
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1 |
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4812 |
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waveguide, SSPD, SNSPD |
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While single photon detectors provide superior intensity sensitivity, spectral resolution is usually lost after the detection event. Yet for applications in low signal infrared spectroscopy recovering information about the photon's frequency contributions is essential. Here we use highly efficient waveguide integrated superconducting single-photon detectors for on-chip coherent detection. In a single nanophotonic device, we demonstrate both single-photon counting with up to 86% on-chip detection efficiency, as well as heterodyne coherent detection with spectral resolution f/f exceeding 10(11). By mixing a local oscillator with the single photon signal field, we observe frequency modulation at the intermediate frequency with ultra-low local oscillator power in the femto-Watt range. By optimizing the nanowire geometry and the working parameters of the detection scheme, we reach quantum-limited sensitivity. Our approach enables to realize matrix integrated heterodyne nanophotonic devices in the C-band wavelength range, for classical and quantum optics applications where single-photon counting as well as high spectral resolution are required simultaneously. |
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National Research University Higher School of Economics, Moscow, 101000, Russia. ggoltsman@hse.ru |
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2045-2322 |
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PMID:28684752; PMCID:PMC5500578 |
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RPLAB @ kovalyuk @ |
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1129 |
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Zolotov, P.; Divochiy, A.; Vakhtomin, Y.; Moshkova, M.; Morozov, P.; Seleznev, V.; Smirnov, K. |
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Photon-number-resolving SSPDs with system detection efficiency over 50% at telecom range |
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2018 |
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Proc. AIP Conf. |
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1936 |
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1 |
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020019 |
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NbN PNR SSPD, SNSPD |
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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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doi:10.1063/1.5025457 |
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1231 |
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