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Okunev O, Chulkova G, Milostnaya I, Antipov A, Smirnov K, Morozov D, et al. Registration of infrared single photons by a two-channel receiver based on fiber-coupled superconducting single-photon detectors. In: Sukhoivanov IA, Svich VA, Shmaliy YS, editors. Proc. SPIE. Vol 7009. SPIE; 2008. 70090V (1 to 8).
Abstract: Single-photon detectors (SPDs) are the foundation of all quantum communications (QC) protocols. Among different classes of SPDs currently studied, NbN superconducting SPDs (SSPDs) are established as the best devices for ultrafast counting of single photons in the infrared (IR) wavelength range. The SSPDs are nanostructured, 100 μm2 in total area, superconducting meanders, patterned by electron lithography in ultra-thin NbN films. Their operation has been explained within a phenomenological hot-electron photoresponse model. We present the design and performance of a novel, two-channel SPD receiver, based on two fiber-coupled NbN SSPDs. The receivers have been developed for fiber-based QC systems, operational at 1.3 μm and 1.55 μm telecommunication wavelengths. They operate in the temperature range from 4.2 K to 2 K, in which the NbN SSPDs exhibit their best performance. The receiver unit has been designed as a cryostat insert, placed inside a standard liquid-heliumstorage dewar. The input of the receiver consists of a pair of single-mode optical fibers, equipped with the standard FC connectors and kept at room temperature. Coupling between the SSPD and the fiber is achieved using a specially designed, precise micromechanical holder that places the fiber directly on top of the SSPD nanostructure. Our receivers achieve the quantum efficiency of up to 7% for near-IR photons, with the coupling efficiency of about 30%. The response time was measured to be < 1.5 ns and it was limited by our read-out electronics. The jitter of fiber-coupled SSPDs is < 35 ps and their dark-count rate is below 1s-1. The presented performance parameters show that our single-photon receivers are fully applicable for quantum correlation-type QC systems, including practical quantum cryptography.
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Schroeder E, Mauskopf P, Pilyavsky G, Sinclair A, Smith N, Bryan S, et al. On the measurement of intensity correlations from laboratory and astronomical sources with SPADs and SNSPDs. In: Malbet F, Creech-Eakman MJ, Tuthill PG, editors. Proc. SPIE. Vol 9907. SPIE; 2016. 99070P (1 to 13).
Abstract: We describe the performance of detector modules containing silicon single photon avalanche photodiodes (SPADs) and superconducting nanowire single photon detectors (SNSPDs) to be used for intensity interferometry. The SPADs are mounted in fiber-coupled and free-space coupled packages. The SNSPDs are mounted in a small liquid helium cryostat coupled to single mode fiber optic cables which pass through a hermetic feed-through. The detectors are read out with microwave amplifiers and FPGA-based coincidence electronics. We present progress on measurements of intensity correlations from incoherent sources including gas-discharge lamps and stars with these detectors. From the measured laboratory performance of the correlation system, we estimate the sensitivity to intensity correlations from stars using commercial telescopes and larger existing research telescopes.
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Shangina EL, Smirnov KV, Morozov DV, Kovalyuk VV, Gol’tsman GN, Verevkin AA, et al. Frequency bandwidth and conversion loss of a semiconductor heterodyne receiver with phonon cooling of two-dimensional electrons. Semicond. 2010;44(11):1427–9.
Abstract: The temperature and concentration dependences of the frequency bandwidth of terahertz heterodyne AlGaAs/GaAs detectors based on hot electron phenomena with phonon cooling of two-dimensional electrons have been measured by submillimeter spectroscopy with a high time resolution. At a temperature of 4.2 K, the frequency bandwidth at a level of 3 dB (f 3 dB) is varied from 150 to 250 MHz with a change in the concentration n s according to the power law f 3dB ∝ n −0.5 s due to the dominant contribution of piezoelectric phonon scattering. The minimum conversion loss of the semiconductor heterodyne detector is obtained in structures with a high carrier mobility (μ > 3 × 105 cm2 V−1 s−1 at 4.2 K).
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Morozov DV, Smirnov KV, Smirnov AV, Lyakhov VA, Goltsman GN. A millimeter-submillimeter phonon-cooled hot-electron bolometer mixer based on two-dimensional electron gas in an AlGaAs/GaAs heterostructure. Semicond. 2005;39(9):1082–6.
Abstract: Experimental results obtained by studying the main characteristics of a millimeter-submillimeter wave mixer based on the hot-electron effect in a two-dimensional electron gas in a AlGaAs/GaAs heterostructure with a phonon-scattering cooling mechanism for charge carriers are reported. The gain bandwidth of the mixer is 4 GHz, the internal conversion losses are 13 dB, and the optimum local-oscillator power is 0.5 μW (for a mixer area of 1 μm2). It is shown that a millimeter-submillimeter-wave receiver with a noise temperature of 1900 K can be developed on the basis of a AlGaAs/GaAs mixer. This mixer also appears to be promising for use in array receiver elements.
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Shangina EL, Smirnov KV, Morozov DV, Kovalyuk VV, Goltsman GN, Verevkin AA, et al. Concentration dependence of energy relaxation time in AlGaAs/GaAs heterojunctions: direct measurements. Semicond Sci Technol. 2011;26(2):025013.
Abstract: We present measurements of the energy relaxation time, τε, of electrons in a single heterojunction in a quasi-equilibrium state using microwave time-resolved spectroscopy at 4.2 K. We find the relaxation time has a power-law dependence on the carrier density of the two-dimensional electron gas, τε∝nγs with γ = 0.40 ± 0.02 for values of the carrier density, ns, from 1.6 × 1011 to 6.6 × 1011cm−2. The results are in good agreement with predictions taking into account the scattering of the carriers by both piezoelectric and deformation potential acoustic phonons. We compare these results with indirect measurements of the energy relaxation time from energy loss measurements involving Joule heating of the electron gas.
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