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Author Trifonov, A.; Tong, C.-Y. E.; Blundell, R.; Ryabchun, S.; Gol'tsman, G. url  doi
openurl 
  Title (down) Probing the stability of HEB mixers with microwave injection Type Journal Article
  Year 2015 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.  
  Volume 25 Issue 3 Pages 2300404 (1 to 4)  
  Keywords NbN HEB mixer, stability, Allan-variance  
  Abstract Using a microwave probe as a tool, we have performed experiments aimed at understanding the origin of the output-power fluctuations in hot-electron-bolometer (HEB) mixers. We use a probe frequency of 1.5 GHz. The microwave probe picks up impedance changes of the HEB, which are examined upon demodulation of the reflected wave outside the cryostat. This study shows that the HEB mixer operates in two different regimes under a terahertz pump. At a low pumping level, strong pulse modulation is observed, as the device switches between the superconducting state and the normal state at a rate of a few megahertz. When pumped much harder, to approximate the low-noise mixer operating point, residual modulation can still be observed, showing that the HEB mixer is intrinsically unstable even in the resistive state. Based on these observations, we introduced a low-frequency termination to the HEB mixer. By terminating the device in a 50-Ω resistor in the megahertz frequency range, we have been able to improve the output-power Allan time of our HEB receiver by a factor of four to about 10 s for a detection bandwidth of 15 MHz, with a corresponding gain fluctuation of about 0.035%.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1051-8223 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1355  
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Author Beck, M.; Klammer, M.; Rousseau, I.; Gol’tsman, G. N.; Diamant, I.; Dagan, Y.; Demsar, J. url  doi
openurl 
  Title (down) Probing superconducting gap dynamics with THz pulses Type Conference Article
  Year 2015 Publication CLEO Abbreviated Journal CLEO  
  Volume Issue Pages SM3H.3 (1 to 2)  
  Keywords superconducting gap; electric fields; femtosecond pulses; near infrared radiation; picosecond pulses; superconductors; thin films  
  Abstract We studied superconducting gap dynamics in a BCS superconductor NbN and electron doped cuprate superconductor PCCO following excitation with near-infrared (NIR) and narrow band THz pulses. Systematic studies on PCCO imply very selective electron-phonon coupling.  
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  Publisher Optical Society of America Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
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  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1345  
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Author Baeva, E.; Sidorova, M.; Korneev, A.; Goltsman, G. url  doi
openurl 
  Title (down) Precise measurement of the thermal conductivity of superconductor Type Conference Article
  Year 2018 Publication Proc. AIP Conf. Abbreviated Journal Proc. AIP Conf.  
  Volume 1936 Issue 1 Pages 020003 (1 to 4)  
  Keywords NbN SSPD, SNSPD  
  Abstract Measuring the thermal properties such as the heat capacity provide information about intrinsic mechanisms operated inside. In general, the ratio between electron and phonon specific heat Ce/Cp shows how the absorbed energy shared between electron and phonon subsystems. In this work we make estimations for amplitude-modulated absorption of THz radiation technique for investigation of the ratio Ce/Cp in superconducting Niobium Nitride (NbN) at T = Tc. Our results indicates that experimentally the frequency of modulation has to be extra large to extract the quantity. We perform a new technique allowed to work at low frequency with accurately measurement of absorbed power.  
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  Notes Approved no  
  Call Number doi:10.1063/1.5025441 Serial 1311  
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Author Gershenzon, E.; Goltsman, G.; Orlov, L.; Ptitsina, N. url  openurl
  Title (down) Population of excited-states of small admixtures in germanium Type Conference Article
  Year 1978 Publication Izv. Akad. Nauk SSSR, Seriya Fizicheskaya Abbreviated Journal Izv. Akad. Nauk SSSR, Seriya Fizicheskaya  
  Volume 42 Issue 6 Pages 1154-1159  
  Keywords Ge, excited states, admixtures  
  Abstract  
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  Publisher Mezhdunarodnaya Kniga 39 Dimitrova Ul., 113095 Moscow, Russia Place of Publication Editor  
  Language Summary Language Original Title  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1723  
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Author Gershenzon, E. M.; Gol'tsman, G. N.; Ptitsina, N. G. url  openurl
  Title (down) Population and lifetime of excited states of shallow impurities in Ge Type Journal Article
  Year 1979 Publication Sov. Phys. JETP Abbreviated Journal Sov. Phys. JETP  
  Volume 49 Issue 2 Pages 355-362  
  Keywords Ge, photothermal ionization, shallow impurities  
  Abstract An investigation was made of the dependences of the intensities of photothermal ionization lines of excited states of shallow impurities in Ge on the intensity of impurity-absorbed background radiation and on temperature. The results obtained were used to find the density and lifetime of carriers of lower excited states of the impurity centers. The lifetimes of the excited states of donors in Ge were 10-~-10-" sec and the lifetime of the lower excited state of acceptors was -lo-' sec. In the presence of background radiation the population of the excited states was very different from the equilibrium value and, in particular, a population inversion of the 2pk, state relative to the 3p0 and 3s states was observed.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1719  
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