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Author Zhang, W.; Khosropanah, P.; Gao, J. R.; Kollberg, E. L.; Yngvesson, K. S.; Bansal, T.; Barends, R.; Klapwijk, T. M. openurl 
  Title Quantum noise in a terahertz hot electron bolometer mixer Type Journal Article
  Year 2010 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.  
  Volume 96 Issue 11 Pages 111113-(1-3)  
  Keywords HEB mixer, quantum limit, quantum noise, vacuum box, THz, Terahertz  
  Abstract (down) We have measured the noise temperature of a single, sensitive superconducting NbN hot electron bolometer (HEB) mixer in a frequency range from 1.6 to 5.3 THz, using a setup with all the key components in vacuum. By analyzing the measured receiver noise temperature using a quantum noise (QN) model for HEB mixers, we confirm the effect of QN. The QN is found to be responsible for about half of the receiver noise at the highest frequency in our measurements. The beta-factor (the quantum efficiency of the HEB) obtained experimentally agrees reasonably well with the calculated value.  
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  Notes Approved no  
  Call Number Serial 624  
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Author Ryabchun, S. A.; Tretyakov, I. V.; Pentin, I. V.; Kaurova, N. S.; Seleznev, V. A.; Voronov, B. M.; Finkel, M. I.; Maslennikov, S. N.; Gol'tsman, G. N. doi  openurl
  Title Low-noise wide-band hot-electron bolometer mixer based on an NbN film Type Journal Article
  Year 2009 Publication Radiophys. Quant. Electron. Abbreviated Journal  
  Volume 52 Issue 8 Pages 576-582  
  Keywords HEB mixer, in-situ contacts, noise temperature, conversion gain bandwidth, diffusion cooling channel  
  Abstract (down) We develop and study a hot-electron bolometer mixer made of a two-layer NbN–Au film in situ deposited on a silicon substrate. The double-sideband noise temperature of the mixer is 750 K at a frequency of 2.5 THz. The conversion efficiency measurements show that at the superconducting transition temperature, the intermediate-frequency bandwidth amounts to about 6.5 GHz for a mixer 0.112 μm long. These record-breaking characteristics are attributed to the improved contacts between a sensitive element and a helical antenna and are reached due to using the in situ deposition of NbN and Au layers at certain stages of the process.  
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  Notes Approved no  
  Call Number Serial 599  
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Author Tretyakov, I. V.; Ryabchun, S. A.; Maslennikov, S. N.; Finkel, M. I.; Kaurova, N. S.; Seleznev, V. A.; Voronov, B. M.; Gol'tsman, G.N. openurl 
  Title NbN HEB mixer: fabrication, noise temperature reduction and characterization Type Conference Article
  Year 2008 Publication Proc. Basic problems of superconductivity Abbreviated Journal  
  Volume Issue Pages  
  Keywords HEB, mixer, noise temperature, conversion gain bandwidth  
  Abstract (down) We demonstrate that in the terahertz region superconducting hot-electron mixers offer the lowest noise temperature, opening the possibility of using HTS's in the future to fabricate these devices. Specifically, a noise temperature of 950 K was measured for the receiver operating at 2.5 THz with a NbN HEB mixer, and a gain bandwidth of 6 GHz was measured at 300 GHz near Tc for the same mixer.  
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  Publisher Place of Publication Moscow-Zvenigorod Editor  
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  Notes Approved no  
  Call Number Serial 591  
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Author Uzawa, Y.; Kojima, T.; Kroug, M.; Takeda, M.; Candotti, M.; Fujii, Y.; Shan, W.-L.; Kaneko, K.; Shitov, S.; Wang, M.-J. openurl 
  Title Development of the 787-950 GHz ALMA band 10 cartridge Type Conference Article
  Year 2009 Publication Proc. 20th Int. Symp. Space Terahertz Technol. Abbreviated Journal  
  Volume Issue Pages 12-12  
  Keywords SIS mixer, noise temperature, ALMA, band 10  
  Abstract (down) We are developing the Atacama Large Millimeter/Submillimeter Array (ALMA) Band 10 (787-950 GHz) receiver cartridge. The incoming beam from the 12-m antenna is reflected by a pair of two ellipsoidal mirrors placed in the cartridge, and then split into two orthogonal polarizations by a free-standing wire-grid. Each beam enters a corrugated feed horn attached to a double-side-band (DSB) mixer block. The mixer uses a full-height waveguide and an NbTiN- or NbN-based superconductor-insulator-superconductor (SIS) mixer chip. We are testing the following three types of mixer chips: 1) Nb SIS junctions + NbTiN/SiO2/Al tuning circuits on a quartz substrate, 2) Nb SIS junctions + NbN/SiO2/Al tuning circuits on an MgO substrate, and 3) NbN SIS junctions + NbN or NbTiN tuning circuits on an MgO substrate. The IF system uses a 4-12-GHz cooled low-noise InP-based MMIC amplifier developed by Caltech. So far, the type 1) has shown the best performance. At LO frequencies from 800 to 940 GHz, the mixer noise temperatures measured by using the standard Y-factor method were below 240 K at an operating physical temperature of 4 K. The lowest noise temperature, 169 K, was obtained at the center frequency of the band 10, as designed. These well-developed technologies will be implemented in the band 10 cartridge to achieve the ALMA specifications.  
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  Notes Approved no  
  Call Number Serial 615  
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Author Archer, J. W. openurl 
  Title Multiple mixer, cryogenic receiver for 200-350 GHz Type Journal Article
  Year 1983 Publication Rev. Sci. Instrum. Abbreviated Journal Rev. Sci. Instrum.  
  Volume 54 Issue 10 Pages 1371-1376  
  Keywords Schottky, mixer, noise temperature  
  Abstract (down) This paper describes a new 200–350-GHz dual polarization heterodyne radiometer receiver for radio astronomy applications. The receiver incorporates four pairs of cryogenically cooled Schottky-barrier diode single-ended mixers, each pair covering a 30–40-GHz subband of the full operating band. Each mixer, with its IF amplifier, is mounted in an individual cryogenic subdewar comprising a separate vcuum chamber and a cold stage, which may be readily thermally connected to or disconnected from the main refrigerator by a novel mechanical heat switch. A dual polarization LO diplexer is mounted on a rotary table above the subdewars. For band selection, the two diplexer rf output ports may be positioned over any of the four pairs of subdewars. The SSB receiver noise temperatues achieved are less than 500 K between 200 and 240 GHz, less than 800 K between 245 and 275 GHz and 1500 K at 345 GHz.  
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  Notes Approved no  
  Call Number Serial 589  
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