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Author Julia Toussaint, Roman Grüner, Marco Schubert, Torsten May, Hans-Georg Meyer, Benjamin Dietzek, Jürgen Popp, Matthias Hofherr, Matthias Arndt, Dagmar Henrich, Konstantin Il'in, and Michael Siegel openurl 
  Title Superconducting single-photon counting system for optical experiments requiring time-resolution in the picosecond range Type Journal Article
  Year 2012 Publication Abbreviated Journal AIP REVIEW OF SCIENTIFIC INSTRUMENTS  
  Volume 83 Issue (down) Pages  
  Keywords SSPD, picosecond, time-resolution  
  Abstract We have developed a cryogenic measurement system for single-photon counting, which can be used

in optical experiments requiring high time resolution in the picosecond range. The system utilizes

niobium nitride superconducting nanowire single-photon detectors which are integrated in a timecorrelated

single-photon counting (TCSPC) setup. In this work, we describe details of the mechanical

design, the electrical setup, and the cryogenic optical components. The performance of the complete

system in TCSPC mode is tentatively benchmarked using 140 fs long laser pulses at a repetition

frequency of 75MHz. Due to the high temporal stability of these pulses, the measured time resolution

of 35 ps (FWHM) is limited by the timing jitter of the measurement system. The result was crosschecked

in a Coherent Anti-stokes Raman Scattering (CARS) setup, where scattered pulses from a

β-barium borate crystal have been detected with the same time resolution.		  
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  Call Number RPLAB @ seleznev @ Serial 885  
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Author Sahu, Mitrabhanu; Bae, Myung-Ho; Rogachev, Andrey; Pekker, David; Wei, Tzu-Chieh; Shah, Nayana; Goldbart, Paul M.; Bezryadin, Alexey doi  openurl
  Title Individual topological tunnelling events of a quantum field probed through their macroscopic consequences Type Journal Article
  Year 2009 Publication Nature Phys. Abbreviated Journal Nature Phys.  
  Volume 5 Issue (down) Pages 503-508  
  Keywords phase slips, superconducting nanowires  
  Abstract Phase slips are topological fluctuations that carry the superconducting order-parameter field between distinct current-carrying states. Owing to these phase slips, superconducting nanowires acquire electrical resistance. In such wires, it is well known that at higher temperatures phase slips occur through the process of thermal barrier-crossing by the order-parameter field. At low temperatures, the general expectation is that phase slips should proceed through quantum tunnelling events, which are known as quantum phase slips. However, resistive measurements have produced evidence both for and against the occurrence of quantum phase slips. Here, we report evidence for the observation of individual quantum phase-slip events in homogeneous ultranarrow wires at high bias currents. We accomplish this through measurements of the distribution of switching currents for which the width exhibits a rather counter-intuitive, monotonic increase with decreasing temperature. Importantly, measurements show that in nanowires with larger critical currents, quantum fluctuations dominate thermal fluctuations up to higher temperatures.  
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  Notes Recommended by Klapwijk Approved no  
  Call Number Serial 928  
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Author - openurl 
  Title ГОСТ 2.125-2008 ЕСКД Правила выполнения эскизных конструкторских документов Type Miscellaneous
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  Call Number RPLAB @ kostochkin @ Serial 934  
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Author Kawamura, J.; Blundell, R.; Tong, C.-Y. E.; Golts'man, G.; Gershenzon, E.; Voronov B. url  openurl
  Title Superconductive NbN hot-electron bolometric mixer performance at 250 GHz Type Conference Article
  Year 1996 Publication Proc. 7th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 7th Int. Symp. Space Terahertz Technol.  
  Volume Issue (down) Pages 331-336  
  Keywords NbN HEB mixers  
  Abstract Thin film NbN (<40 A) strips are used as waveguide mixer elements. The electron cooling mechanism for the geometry is the electron-phonon interaction. We report a receiver noise temperature of 750 K at 244 GHz, with / IF = 1.5 GHz, Af= 500 MHz, and Tphysical = 4 K. The instantaneous bandwidth for this mixer is 1.6 GHz. The local oscillator (LO) power is 0.5 1.tW with 3 dB-uncertainty. The mixer is linear to 1 dB up to an input power level 6 dB below the LO power. We report the first detection of a molecular line emission using this class of mixer, and that the receiver noise temperature determined from Y-factor measurements reflects the true heterodyne sensitivity.  
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  Call Number Serial 945  
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Author Kerr, A. R.; Feldman, M. J.; Pan, S.-K. openurl 
  Title Receiver noise temperature, the quantum noise limit, and the role of the zero-point fluctuations Type Journal Article
  Year 1996 Publication Electronics division internal report NO. 304 Abbreviated Journal  
  Volume Issue (down) Pages 1-10  
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  Call Number RPLAB @ atomics90 @ Serial 947  
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Author Shurakov, A.; Tong, Cheuk-yu E.; Grimes, P.; Blundell, R.; Golt'sman, G. openurl 
  Title A microwave reflection readout scheme for hot electron bolometric direct detector Type Journal Article
  Year 2015 Publication IEEE Trans. THz Sci. Technol. Abbreviated Journal IEEE Trans. THz Sci. Technol.  
  Volume 5 Issue (down) Pages 81-84  
  Keywords HEB detectors  
  Abstract In this paper, we propose and present data from a fast THz detector based on the repurpose of hot electron bolometer mixers (HEB) fabricated from superconducting NbN thinfilm. This detector is essentially a traditional NbN bolometer element that operates under the influence of a microwave pump. The in-jected microwave power serves the dual purpose of enhancing the detector sensitivity and reading out the impedance changes of the device in response to incidentTHz radiation. We have measured an optical Noise Equivalent Power of 4 pW/ Hz for our detector at a bath temperature of 4.2 K. The measurement frequency was 0.83 THz and the modulation frequency was 1.48 kHz. The readout

scheme is versatile and facilitates both high-speed operation as well as multi-pixel applications.		  
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  Call Number RPLAB @ atomics90 @ Serial 950  
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Author Meledin D.; Desmaris V.; Ferm S.-E.; Fredrixon M.; Henke D.; Lapkin I.; Nyström O.; Pantaleev M.; Pavolotsky A.; Strandberg M.; Sundin E.; Belitsky V. openurl 
  Title APEX Band T2: A 1.25 – 1.39 THz Waveguide Balanced HEB Receiver Type Journal Article
  Year 2008 Publication Abbreviated Journal  
  Volume Issue (down) Pages 181-185  
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  Abstract A waveguide 1.25–1.39 THz Hot Electron Bolometer (HEB) balanced receiver was successfully developed, characterized and installed at the Atacama Pathfinder EXperiment (APEX) telescope. The receiver employs a quadrature balanced scheme using a waveguide 90-degree 3 dB RF hybrid, HEB mixers and a 180-degree IF hybrid. The HEB mixers are based on ultrathin NbN film deposited on crystalline quartz with a MgO buffer layer. Integrated into the multi-channel APEX facility receiver (SHeFI), the results presented here demonstrate exceptional performance; a receiver noise temperature of 1000 K measured at the telescope at the center of the receiver IF band 2-4 GHz, and at an LO frequency of 1294 GHz. Stability of the receiver is fully in line with the SIS mixer bands of the SHeFI, and gives a spectroscopic Allan time of more than 200 s with a noise bandwidth of 1 MHz.  
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  Call Number RPLAB @ atomics90 @ Serial 974  
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Author Benz, A. O.; Bruderer, S.; van Dishoeck, E. F.; Stäuber, P.; Wampfler, S. F.; Melchior, M.; Dedes, C.; Wyrowski, F.; Doty, S. D.; van der Tak, F.; Bächtold, W.; Csillaghy, A.; Megej, A.; Monstein, C.; Soldati, M.; Bachiller, R.; Baudry, A.; Benedettini, M.; Bergin, E.; Bjerkeli, P.; Blake, G. A.; Bontemps, S.; Braine, J.; Caselli, P.; Cernicharo, J.; Codella, C.; Daniel, F.; di Giorgio, A. M.; Dieleman, P.; Dominik, C.; Encrenaz, P.; Fich, M.; Fuente, A.; Giannini, T.; Goicoechea, J. R.; de Graauw, Th.; Helmich, F.; Herczeg, G. J.; Herpin, F.; Hogerheijde, M. R.; Jacq, T.; Jellema, W.; Johnstone, D.; Jørgensen, J. K.; Kristensen, L. E.; Larsson, B.; Lis, D.; Liseau, R.; Marseille, M.; McCoey, C.; Melnick, G.; Neufeld, D.; Nisini, B.; Olberg, M.; Ossenkopf, V.; Parise, B.; Pearson, J. C.; Plume, R.; Risacher, C.; Santiago-García, J.; Saraceno, P.; Schieder, R.; Shipman, R.; Stutzki, J.; Tafalla, M.; Tielens, A. G. G. M.; van Kempen, T. A.; Visser, R.; Yıldız, U. A. doi  openurl
  Title Hydrides in young stellar objects: Radiation tracers in a protostar-disk-outflow system Type Journal Article
  Year 2010 Publication Astron. Astrophys. Abbreviated Journal  
  Volume 521 Issue (down) Pages L35 (1 to 5)  
  Keywords HEB mixer applications, HIFI, Herschel  
  Abstract Context. Hydrides of the most abundant heavier elements are fundamental molecules in cosmic chemistry. Some of them trace gas irradiated by UV or X-rays.

Aims. We explore the abundances of major hydrides in W3 IRS5, a prototypical region of high-mass star formation.

Methods. W3 IRS5 was observed by HIFI on the Herschel Space Observatory with deep integration (2500 s) in 8 spectral regions.

Results. The target lines including CH, NH, H3O+, and the new molecules SH+, H2O+, and OH+ are detected. The H2O+ and OH+ J = 1–0 lines are found mostly in absorption, but also appear to exhibit weak emission (P-Cyg-like). Emission requires high density, thus originates most likely near the protostar. This is corroborated by the absence of line shifts relative to the young stellar object (YSO). In addition, H2O+ and OH+ also contain strong absorption components at a velocity shifted relative to W3 IRS5, which are attributed to foreground clouds.

Conclusions. The molecular column densities derived from observations correlate well with the predictions of a model that assumes the main emission region is in outflow walls, heated and irradiated by protostellar UV radiation.		  
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  Call Number Serial 1082  
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Author Bujarrabal, V.; Alcolea, J.; Soria-Ruiz, R.; Planesas, P.; Teyssier, D.; Marston, A. P.; Cernicharo, J.; Decin, L.; Dominik, C.; Justtanont, K.; de Koter, A.; Melnick, G.; Menten, K. M.; Neufeld, D. A.; Olofsson, H.; Schmidt, M.; Schöier, F. L.; Szczerba, R.; Waters, L. B. F. M.; Quintana-Lacaci, G.; Güsten, R.; Gallego, J. D.; Díez-González, M. C.; Barcia, A.; López-Fernández, I.; Wildeman, K.; Tielens, A. G. G. M.; Jacobs, K. doi  openurl
  Title Herschel/HIFI observations of high-J CO transitions in the protoplanetary nebula CRL 618 Type Journal Article
  Year 2010 Publication Astron. Astrophys. Abbreviated Journal  
  Volume 521 Issue (down) Pages L3 (1 to 5)  
  Keywords HEB mixer applications, HIFI, Herschel  
  Abstract Aims. We aim to study the physical conditions, particularly the excitation state, of the intermediate-temperature gas components in the protoplanetary nebula CRL 618. These components are particularly important for understanding the evolution of the nebula.

Methods. We performed Herschel/HIFI observations of several CO lines in the far-infrared/sub-mm in the protoplanetary nebula CRL 618. The high spectral resolution provided by HIFI allows measurement of the line profiles. Since the dynamics and structure of the nebula is well known from mm-wave interferometric maps, it is possible to identify the contributions of the different nebular components (fast bipolar outflows, double shells, compact slow shell) to the line profiles. The observation of these relatively high-energy transitions allows an accurate study of the excitation conditions in these components, particularly in the warm ones, which cannot be properly studied from the low-energy lines.

Results. The 12CO J = 16–15, 10–9, and 6–5 lines are easily detected in this source. Both 13CO J = 10–9 and 6–5 are also detected. Wide profiles showing spectacular line wings have been found, particularly in 12CO J = 16–15. Other lines observed simultaneously with CO are also shown. Our analysis of the CO high-J transitions, when compared with the existing models, confirms the very low expansion velocity of the central, dense component, which probably indicates that the shells ejected during the last AGB phases were driven by radiation pressure under a regime of maximum transfer of momentum. No contribution of the diffuse halo found from mm-wave data is identified in our spectra, because of its low temperature. We find that the fast bipolar outflow is quite hot, much hotter than previously estimated; for instance, gas flowing at 100 km s-1 must have a temperature higher than ~200 K. Probably, this very fast outflow, with a kinematic age <100 yr, has been accelerated by a shock and has not yet cooled down. The double empty shell found from mm-wave mapping must also be relatively hot, in agreement with the previous estimate.		  
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  Call Number Serial 1084  
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Author Cavalié, T.; Feuchtgruber, H.; Lellouch, E.; de Val-Borro, M.; Jarchow, C.; Moreno, R.; Hartogh, P.; Orton, G.; Greathouse, T. K.; Billebaud, F.; Dobrijevic, M.; Lara, L. M.; González, A.; Sagawa, H. doi  openurl
  Title Spatial distribution of water in the stratosphere of Jupiter from Herschel HIFI and PACS observations Type Journal Article
  Year 2013 Publication Astron. Astrophys. Abbreviated Journal  
  Volume 553 Issue (down) Pages A21 (1 to 16)  
  Keywords HEB mixer applications, HIFI, Herschel  
  Abstract Context. In the past 15 years, several studies suggested that water in the stratosphere of Jupiter originated from the Shoemaker-Levy 9 (SL9) comet impacts in July 1994, but a direct proof was missing. Only a very sensitive instrument observing with high spectral/spatial resolution can help to solve this problem. This is the case of the Herschel Space Observatory, which is the first telescope capable of mapping water in Jupiter's stratosphere.

Aims. We observed the spatial distribution of the water emission in Jupiter's stratosphere with the Heterodyne Instrument for the Far Infrared (HIFI) and the Photodetector Array Camera and Spectrometer (PACS) onboard Herschel to constrain its origin. In parallel, we monitored Jupiter's stratospheric temperature with the NASA Infrared Telescope Facility (IRTF) to separate temperature from water variability.

Methods. We obtained a 25-point map of the 1669.9 GHz water line with HIFI in July 2010 and several maps with PACS in October 2009 and December 2010. The 2010 PACS map is a 400-point raster of the water 66.4 μm emission. Additionally, we mapped the methane ν4 band emission to constrain the stratospheric temperature in Jupiter in the same periods with the IRTF.

Results. Water is found to be restricted to pressures lower than 2 mbar. Its column density decreases by a factor of 2–3 between southern and northern latitudes, consistently between the HIFI and the PACS 66.4 μm maps. We infer that an emission maximum seen around 15 °S is caused by a warm stratospheric belt detected in the IRTF data.

Conclusions. Latitudinal temperature variability cannot explain the global north-south asymmetry in the water maps. From the latitudinal and vertical distributions of water in Jupiter's stratosphere, we rule out interplanetary dust particles as its main source. Furthermore, we demonstrate that Jupiter's stratospheric water was delivered by the SL9 comet and that more than 95% of the observed water comes from the comet according to our models.		  
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  Notes Approved no  
  Call Number Serial 1085  
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