Ryabchun, S., Tong, C. - Y. E., Paine, S., Lobanov, Y., Blundell, R., & Goltsman, G. (2009). Temperature resolution of an HEB receiver at 810 GHz. IEEE Trans. Appl. Supercond., 19(3), 293–296.
Abstract: We present the results of direct measurements of the temperature resolution of an HEB receiver operating at 810 GHz, in both continuum and spectroscopic modes. In the continuum mode, the input of the receiver was switched between black bodies with different physical temperatures. With a system noise temperature of around 1100 K, the receiver was able to resolve loads which differed in temperature by about 1 K over an integration time of 5 seconds. This resolution is significantly worse than the value of 0.07 K given by the radiometer equation. In the spectroscopic mode, a gas cell filled with carbonyl sulphide (OCS) gas was used and the emission line at 813.3537060 GHz was measured using the receiver in conjunction with a digital spectrometer. From the observed spectra, we determined that the measurement uncertainty of the equivalent emission temperature was 2.8 K for an integration time of 0.25 seconds and a spectral resolution of 12 MHz, compared to a 1.4 K temperature resolution given by the radiometer equation. This relative improvement is due to the fact that at short integration times the contribution from 1/f noise and drift are less dominant. In both modes, the temperature resolution was improved by about 40% with the use of a feedback loop which adjusted the level of an injected microwave radiation to maintain a constant operating current of the HEB mixer. This stabilization scheme has proved to be very effective to keep the temperature resolution of the HEB receiver to close to the theoretical value given by the radiometer equation.
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Huang, K. C. Y., Jun, Y. C., Seo, M. - K., & Brongersma, M. L. (2011). Power flow from a dipole emitter near an optical antenna. Opt. Express, 19(20), 19084–19092.
Abstract: Current methods to calculate the emission enhancement of a quantum emitter coupled to an optical antenna of arbitrary geometry rely on analyzing the total Poynting vector power flow out of the emitter or the dyadic Green functions from full-field numerical simulations. Unfortunately, these methods do not provide information regarding the nature of the dominant energy decay pathways. We present a new approach that allows for a rigorous separation, quantification, and visualization of the emitter output power flow captured by an antenna and the subsequent reradiation power flow to the far field. Such analysis reveals unprecedented details of the emitter/antenna coupling mechanisms and thus opens up new design strategies for strongly interacting emitter/antenna systems used in sensing, active plasmonics and metamaterials, and quantum optics.
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Гершензон, Е. М., Литвак-Горская, Л. Б., Луговая, Г. Я., & Шапиро, Е. З. (1986). Об интерпретации отрицательного магнитосопротивления в случае проводимости по верхней зоне Хаббарда в n-Ge⟨Sb⟩. Физика и техника полупроводников, 20(1), 99–103.
Abstract: В рамках теории квантовых поправок к проводимости объяснено отрицательное магнитосопротивление в n-Ge с концентрацией доноров Nd≃2.8⋅1016÷1.1⋅1017см−3, наблюдаемое в диапазоне температур 4.2−10 K, когда основной вклад в проводимость дают электроны верхней зоны Хаббарда. Показано, что время релаксации фазы волновой функции τφ определяется временем электрон-фононного взаимодействия τeph.
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Semenov, A., Engel, A., Il'in, K., Gol'tsman, G., Siegel, M., & Hübers, H. - W. (2003). Ultimate performance of a superconducting quantum detector. Eur. Phys. J. Appl. Phys., 21(3), 171–178.
Abstract: We analyze the ultimate performance of a superconducting quantum detector in order to meet requirements for applications in near-infrared astronomy and X-ray spectroscopy. The detector exploits a combined detection mechanism, in which avalanche quasiparticle multiplication and the supercurrent jointly produce a voltage response to a single absorbed photon via successive formation of a photon-induced and a current-induced normal hotspot in a narrow superconducting strip. The response time of the detector should increase with the photon energy providing energy resolution. Depending on the superconducting material and operation conditions, the cut-off wavelength for the single-photon detection regime varies from infrared waves to visible light. We simulated the performance of the background-limited infrared direct detector and X-ray photon counter utilizing the above mechanism. Low dark count rate and intrinsic low-frequency cut-off allow for realizing a background limited noise equivalent power of 10−20 W Hz−1/2 for a far-infrared direct detector exposed to 4-K background radiation. At low temperatures, the intrinsic response time of the counter is rather determined by diffusion of nonequilibrium electrons than by the rate of energy transfer to phonons. Therefore, thermal fluctuations do not hamper energy resolution of the X-ray photon counter that should be better than 10−3 for 6-keV photons. Comparison of new data obtained with a Nb based detector and previously reported results on NbN quantum detectors support our estimates of ultimate detector performance.
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Lobanov, Y. V., Tong, C. - Y. E., Hedden, A. S., Blundell, R., Voronov, B. M., & Gol'tsman, G. N. (2011). Direct measurement of the gain and noise bandwidths of HEB mixers. IEEE Trans. Appl. Supercond., 21(3), 645–648.
Abstract: The intermediate frequency (IF) bandwidth of a hot electron bolometer (HEB) mixer is an important parameter of the mixer, in that it helps to determine its suitability for a given application. With the availability of wideband low noise amplifiers, it is simple to measure the performance of an HEB mixer over a wide range of IF at a fixed LO frequency using the standard Y-factor method. This in-situ method allows us to measure both the gain and noise bandwidths simultaneously. We have also measured mixer output impedance with a vector network analyser. Intrinsic time constant has been extracted from the impedance data and compared to the mixer's bandwidths determined from receiver Y-factor measurement.
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Shurakov, A., Tong, C. - Y. E., Blundell, R., Kaurova, N., Voronov, B., & Gol'tsman, G. (2013). Microwave stabilization of a HEB mixer in a pulse-tube cryocooler. IEEE Trans. Appl. Supercond., 23(3), 1501504.
Abstract: We report the results of our study of the stability of an 800 GHz hot electron bolometer (HEB) mixer cooled with a pulse-tube cryocooler. Pulse-tube cryocoolers introduce temperature fluctuations as well as mechanical vibrations at a frequency of ~1 Hz, both of which can cause receiver gain fluctuations at that frequency. In our system, the motor of the cryocooler was separated from the cryostat to minimize mechanical vibrations, leaving thermal effects as the dominant source of the receiver gain fluctuations. We measured root mean square temperature variations of the 4 K stage of ~7 mK. The HEB mixer was pumped by a solid state local oscillator at 810 GHz. The root mean square current fluctuations at the low noise operating point (1.50 mV, 56.5 μA) were ~0.12 μA, and were predominantly due to thermal fluctuations. To stabilize the bias current, microwave radiation was injected to the HEB mixer. The injected power level was set by a proportional-integral-derivative controller, which completely compensates for the bias current oscillations induced by the pulse-tube cryocooler. Significant improvement in the Allan variance of the receiver output power was obtained, and an Allan time of 5 s was measured.
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Wild, W., Kardashev, N. S., Likhachev, S. F., Babakin, N. G., Arkhipov, V. Y., Vinogradov, I. S., et al. (2009). Millimetron—a large Russian-European submillimeter space observatory. Exp. Astron., 23(1), 221–244.
Abstract: Millimetron is a Russian-led 12 m diameter submillimeter and far-infrared space observatory which is included in the Space Plan of the Russian Federation for launch around 2017. With its large collecting area and state-of-the-art receivers, it will enable unique science and allow at least one order of magnitude improvement with respect to the Herschel Space Observatory. Millimetron will be operated in two basic observing modes: as a single-dish observatory, and as an element of a ground-space very long baseline interferometry (VLBI) system. As single-dish, angular resolutions on the order of 3 to 12 arc sec will be achieved and spectral resolutions of up to a million employing heterodyne techniques. As VLBI antenna, the chosen elliptical orbit will provide extremely large VLBI baselines (beyond 300,000 km) resulting in micro-arc second angular resolution.
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Zhang, W., Li, N., Jiang, L., Miao, W., Lin, Z. - H., Yao, Q. - J., et al. (2007). Noise behaviour of a THz superconducting hot-electron bolometer mixer. Chinese Phys. Lett., 24(6), 1778–1781.
Abstract: A quasi-optical superconducting NbN hot-electron bolometer (HEB) mixer is measured in the frequency range of 0.5–2.5 THz for understanding of the frequency dependence of noise temperature of THz coherent detectors. It has been found that noise temperature increasing with frequency is mainly due to the coupling loss between the quasi-optical planar antenna and the superconducting HEB bridge when taking account of non-uniform distribution of high-frequency current. With the coupling loss corrected, the superconducting HEB mixer demonstrates a noise temperature nearly independent of frequency.
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Банная, В. Ф., Веселова, Л. И., Гершензон, Е. М., Гусинский, Э. Н., & Литвак-Горская, Л. Б. (1990). Оценка точности метода определения раздельной концентрации примесей из измерений постоянной Холла. Физика и техника полупроводников, 24(12), 2145–2150.
Abstract: На примере p-Si⟨B,\,Ga⟩ с различной степенью компенсации проведена сравнительная оценка точности определения раздельной концентрации примесей по температурной зависимости концентрации дырок p(T) в случае одной и двух легирующих примесей с энергиями ионизации, различающимися менее чем в 2 раза. Исследована функция среднеквадратичного отклонения в пространстве параметров D(Nк, N2) (Nк, N1 и N2 — концентрации компенсирующих примесей бора и галлия соответственно, N2≫N1) в предположении, что N2, энергии B и Ga известны. Показано, что в случае двух легирующих примесей D(Nк, N1) в окрестностях минимума имеет «овражный» рельеф и при некоторых соотношениях между Nк и N1 разброс искомых величин превышает порядок, причем увеличение точности измерений p(T) существенного улучшения в вычислении параметров не дает. При одной легирующей примеси точность вычисления параметров высокая.
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Гальперин, Ю. М., Гершензон, Е. М., Дричко, И. Л., & Литвак-Горская, Л. Б. (1990). Кинетические явления в компенсированном n-InSb при низких температурах. Физика и техника полупроводников, 24(1), 3–24.
Abstract: Представлен обзор результатов цикла исследований природы электропроводности предельно очищенных образцов антимонида индия n-типа. Рассмотрены способы определения концентрации доноров и степени компенсации в этом материале, обсуждается роль свободных и локализованных на донорах электронов в электропроводности при гелиевых температурах. Обсуждение основано на анализе результатов исследования гальваномагнитных явлений, поглощения СВЧ излучения миллиметрового и субмиллиметрового диапазонов и ультразвука. Рассмотрены способы определения характеристик материала на основе комплекса результатов, полученных с помощью указанных методов. Обсуждается также фотопроводимость по примесям в n-InSb.
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