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Author | Decin, L.; Justtanont, K.; De Beck, E.; Lombaert, R.; de Koter, A.; Waters, L. B. F. M.; Marston, A. P.; Teyssier, D.; Schöier, F. L.; Bujarrabal, V.; Alcolea, J.; Cernicharo, J.; Dominik, C.; Melnick, G.; Menten, K.; Neufeld, D. A.; Olofsson, H.; Planesas, P.; Schmidt, M.; Szczerba, R.; de Graauw, T.; Helmich, F.; Roelfsema, P.; Dieleman, P.; Morris, P.; Gallego, J. D.; Díez-González, M. C.; Caux, E. | ||||
Title | Water content and wind acceleration in the envelope around the oxygen-rich AGB star IK Tauri as seen by Herschel/HIFI | Type | Journal Article | ||
Year | 2010 | Publication | Astron. Astrophys. | Abbreviated Journal | |
Volume | 521 | Issue | Pages | L4 | |
Keywords | HEB mixer applications, HIFI, Herschel, line: profiles / radiative transfer / instrumentation: spectrographs / stars: AGB and post-AGB / circumstellar matter / submillimeter: stars | ||||
Abstract | During their asymptotic giant branch evolution, low-mass stars lose a significant fraction of their mass through an intense wind, enriching the interstellar medium with products of nucleosynthesis. We observed the nearby oxygen-rich asymptotic giant branch star IK Tau using the high-resolution HIFI spectrometer onboard Herschel. We report on the first detection of H216O and the rarer isotopologues H217O and H218O in both the ortho and para states. We deduce a total water content (relative to molecular hydrogen) of $6.6 \times 10^{-5}$, and an ortho-to-para ratio of 3:1. These results are consistent with the formation of H2O in thermodynamical chemical equilibrium at photospheric temperatures, and does not require pulsationally induced non-equilibrium chemistry, vaporization of icy bodies or grain surface reactions. High-excitation lines of 12CO, 13CO, 28SiO, 29SiO, 30SiO, HCN, and SO have also been detected. From the observed line widths, the acceleration region in the inner wind zone can be characterized, and we show that the wind acceleration is slower than hitherto anticipated. | ||||
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Call Number | Serial | 1090 | |||
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Author | Mookerjea, B.; Giesen, T.; Stutzki, J.; Cernicharo, J.; Goicoechea, J. R.; De Luca, M.; Bell, T. A.; Gupta, H.; Gerin, M.; Persson, C. M.; Sonnentrucker, P.; Makai, Z.; Black, J.; Boulanger, F.; Coutens, A.; Dartois, E.; Encrenaz, P.; Falgarone, E.; Geballe, T.; Godard, B.; Goldsmith, P. F.; Gry, C.; Hennebelle, P.; Herbst, E.; Hily-Blant, P.; Joblin, C.; Ka<c5><ba>mierczak, M.; Kołos, R.; Krełowski, J.; Lis, D. C.; Martin-Pintado, J.; Menten, K. M.; Monje, R.; Pearson, J. C.; Perault, M.; Phillips, T. G.; Plume, R.; Salez, M.; Schlemmer, S.; Schmidt, M.; Teyssier, D.; Vastel, C.; Yu, S.; Dieleman, P.; Güsten, R.; Honingh, C. E.; Morris, P.; Roelfsema, P.; Schieder, R.; Tielens, A. G. G. M.; Zmuidzinas, J. | ||||
Title | Excitation and abundance of C3 in star forming cores. Herschel/HIFI observations of the sight-lines to W31C and W49N | Type | Journal Article | ||
Year | 2010 | Publication | Astron. Astrophys. | Abbreviated Journal | |
Volume | 521 | Issue | Pages | L13 | |
Keywords | HEB mixer applications, HIFI, Herschel, ISM: lines and bands / ISM: molecules / radiative transfer / ISM: individual objects: W49N / ISM: individual objects: W31C | ||||
Abstract | We present spectrally resolved observations of triatomic carbon (C3) in several ro-vibrational transitions between the vibrational ground state and the low-energy ν2 bending mode at frequencies between 1654–1897 GHz along the sight-lines to the submillimeter continuum sources W31C and W49N, using Herschel's HIFI instrument. We detect C3 in absorption arising from the warm envelope surrounding the hot core, as indicated by the velocity peak position and shape of the line profile. The sensitivity does not allow to detect C3 absorption due to diffuse foreground clouds. From the column densities of the rotational levels in the vibrational ground state probed by the absorption we derive a rotation temperature (Trot) of ~50-70 K, which is a good measure of the kinetic temperature of the absorbing gas, as radiative transitions within the vibrational ground state are forbidden. It is also in good agreement with the dust temperatures for W31C and W49N. Applying the partition function correction based on the derived Trot, we get column densities N(C3) ~ 7–9 × 1014 cm-2 and abundance x(C3) ~ 10-8 with respect to H2. For W31C, using a radiative transfer model including far-infrared pumping by the dust continuum and a temperature gradient within the source along the line of sight we find that a model with x(C3) = 10-8, Tkin = 30–50 K, N(C3) = 1.5 × 1015 cm-2 fits the observations reasonably well and provides parameters in very good agreement with the simple excitation analysis. | ||||
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Notes | Approved | no | |||
Call Number | Serial | 1099 | |||
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Author | Wampfler, S. F.; Herczeg, G. J.; Bruderer, S.; Benz, A. O.; van Dishoeck, E. F.; Kristensen, L. E.; Visser, R.; Doty, S. D.; Melchior, M.; van Kempen, T. A.; Yıldız, U. A.; Dedes, C.; Goicoechea, J. R.; Baudry, A.; Melnick, G.; Bachiller, R.; 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.; Dominik, C.; Encrenaz, P.; Fich, M.; Fuente, A.; Giannini, T.; de Graauw, Th.; Helmich, F.; Herpin, F.; Hogerheijde, M. R.; Jacq, T.; Johnstone, D.; Jørgensen, J. K.; Larsson, B.; Lis, D.; Liseau, R.; Marseille, M.; Mc Coey, C.; Neufeld, D.; Nisini, B.; Olberg, M.; Parise, B.; Pearson, J. C.; Plume, R.; Risacher, C.; Santiago-García, J.; Saraceno, P.; Shipman, R.; Tafalla, M.; van der Tak, F. F. S.; Wyrowski, F.; Roelfsema, P.; Jellema, W.; Dieleman, P.; Caux, E.; Stutzki, J. | ||||
Title | Herschel observations of the hydroxyl radical (OH) in young stellar objects | Type | Journal Article | ||
Year | 2010 | Publication | Astron. Astrophys. | Abbreviated Journal | |
Volume | 521 | Issue | Pages | L36 | |
Keywords | HEB mixer applications, HIFI, Herschel, astrochemistry / stars: formation / ISM: molecules / ISM: jets and outflows / ISM: individual objects: HH 46 | ||||
Abstract | Aims. “Water In Star-forming regions with Herschel†(WISH) is a Herschel key program investigating the water chemistry in young stellar objects (YSOs) during protostellar evolution. Hydroxyl (OH) is one of the reactants in the chemical network most closely linked to the formation and destruction of H2O. High-temperature (T 250 K) chemistry connects OH and H2O through the OH + H2 H2O + H reactions. Formation of H2O from OH is efficient in the high-temperature regime found in shocks and the innermost part of protostellar envelopes. Moreover, in the presence of UV photons, OH can be produced from the photo-dissociation of H2O through H2O + γUV OH + H. Methods. High-resolution spectroscopy of the 163.12 μm triplet of OH towards HH 46 and NGC 1333 IRAS 2A was carried out with the Heterodyne Instrument for the Far Infrared (HIFI) on board the Herschel Space Observatory. The low- and intermediate-mass protostars HH 46, TMR 1, IRAS 15398-3359, DK Cha, NGC 7129 FIRS 2, and NGC 1333 IRAS 2A were observed with the Photodetector Array Camera and Spectrometer (PACS) on Herschel in four transitions of OH and two [O i] lines. Results. The OH transitions at 79, 84, 119, and 163 μm and [O i] emission at 63 and 145μm were detected with PACS towards the class I low-mass YSOs as well as the intermediate-mass and class I Herbig Ae sources. No OH emission was detected from the class 0 YSO NGC 1333 IRAS 2A, though the 119 μm was detected in absorption. With HIFI, the 163.12 μm was not detected from HH 46 and only tentatively detected from NGC 1333 IRAS 2A. The combination of the PACS and HIFI results for HH 46 constrains the line width (FWHM 11 km s-1) and indicates that the OH emission likely originates from shocked gas. This scenario is supported by trends of the OH flux increasing with the [O i] flux and the bolometric luminosity, as found in our sample. Similar OH line ratios for most sources suggest that OH has comparable excitation temperatures despite the different physical properties of the sources. |
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Notes | Approved | no | |||
Call Number | Serial | 1103 | |||
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Author | Arutyunov, K. Y.; Ramos-Alvarez, A.; Semenov, A. V.; Korneeva, Y. P.; An, P. P.; Korneev, A. A.; Murphy, A.; Bezryadin, A.; Gol'tsman, G. N. | ||||
Title | Superconductivity in highly disordered NbN nanowires | Type | Journal Article | ||
Year | 2016 | Publication | Nanotechnol. | Abbreviated Journal | Nanotechnol. |
Volume | 27 | Issue | 47 | Pages | 47lt02 (1 to 8) |
Keywords | NbN nanowires | ||||
Abstract | The topic of superconductivity in strongly disordered materials has attracted significant attention. These materials appear to be rather promising for fabrication of various nanoscale devices such as bolometers and transition edge sensors of electromagnetic radiation. The vividly debated subject of intrinsic spatial inhomogeneity responsible for the non-Bardeen-Cooper-Schrieffer relation between the superconducting gap and the pairing potential is crucial both for understanding the fundamental issues of superconductivity in highly disordered superconductors, and for the operation of corresponding nanoelectronic devices. Here we report an experimental study of the electron transport properties of narrow NbN nanowires with effective cross sections of the order of the debated inhomogeneity scales. The temperature dependence of the critical current follows the textbook Ginzburg-Landau prediction for the quasi-one-dimensional superconducting channel I c approximately (1-T/T c)(3/2). We find that conventional models based on the the phase slip mechanism provide reasonable fits for the shape of R(T) transitions. Better agreement with R(T) data can be achieved assuming the existence of short 'weak links' with slightly reduced local critical temperature T c. Hence, one may conclude that an 'exotic' intrinsic electronic inhomogeneity either does not exist in our structures, or, if it does exist, it does not affect their resistive state properties, or does not provide any specific impact distinguishable from conventional weak links. | ||||
Address | National Research University Higher School of Economics, Moscow Institute of Electronics and Mathematics,109028, Moscow, Russia. P L Kapitza Institute for Physical Problems RAS, Moscow, 119334, Russia | ||||
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Language | English | Summary Language | Original Title | ||
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ISSN | 0957-4484 | ISBN | Medium | ||
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Notes | PMID:27782000 | Approved | no | ||
Call Number | Serial | 1332 | |||
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Author | Elezov, M. S.; Semenov, A. V.; An, P. P.; Tarkhov, M. A.; Goltsman, G. N.; Kardakova, A. I.; Kazakov, A. Y. | ||||
Title | Investigating the detection regimes of a superconducting single-photon detector | Type | Journal Article | ||
Year | 2013 | Publication | J. Opt. Technol. | Abbreviated Journal | J. Opt. Technol. |
Volume | 80 | Issue | 7 | Pages | 435 |
Keywords | SSPD, quantum efficiency | ||||
Abstract | The detection regimes of a superconducting single-photon detector have been investigated. A technique is proposed for determining the regions in which “pure regimes” predominate. Based on experimental data, the dependences of the internal quantum efficiency on the bias current are determined in the one-, two-, and three-photon detection regimes. | ||||
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ISSN | 1070-9762 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | Approved | no | |||
Call Number | Serial | 1172 | |||
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Author | Komrakova, S.; Kovalyuk, V.; An, P.; Golikov, A.; Rybin, M.; Obraztsova, E.; Goltsman, G. | ||||
Title | Effective absorption coefficient of a graphene atop of silicon nitride nanophotonic circuit | Type | Conference Article | ||
Year | 2020 | Publication | J. Phys.: Conf. Ser. | Abbreviated Journal | J. Phys.: Conf. Ser. |
Volume | 1695 | Issue | Pages | 012135 | |
Keywords | silicon nitride O-ring resonator, ORR | ||||
Abstract | In this paper, we demonstrate the results of a study of the optical absorption properties of graphene integrated with silicon nitride O-ring resonator. We fabricated an array of O-ring resonators with different graphene coverage area atop. By measuring the transmission spectra of nanophotonic devices with and without graphene, we calculated the effective absorption coefficient of the graphene on a rib silicon nitride waveguide. | ||||
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Series Volume | Series Issue | Edition | |||
ISSN | 1742-6588 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | Approved | no | |||
Call Number | Serial | 1177 | |||
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Author | Prokhodtsov, A.; Kovalyuk, V.; An, P.; Golikov, A.; Shakhovoy, R.; Sharoglazova, V.; Udaltsov, A.; Kurochkin, Y.; Goltsman, G. | ||||
Title | Silicon nitride Mach-Zehnder interferometer for on-chip quantum random number generation | Type | Conference Article | ||
Year | 2020 | Publication | J. Phys.: Conf. Ser. | Abbreviated Journal | J. Phys.: Conf. Ser. |
Volume | 1695 | Issue | Pages | 012118 | |
Keywords | Mach-Zehnder interferometer, MZI | ||||
Abstract | In this work, we experimentally studied silicon nitride Mach-Zehnder interferometer (MZI) with two directional couplers and 400 ps optical delay line for telecom wavelength 1550 nm. We achieved the extinction ratio in a range of 0.76-13.86 dB and system coupling losses of 28-44 dB, depending on the parameters of directional couplers. The developed interferometer is promising for the use in a compact random number generator for the needs of a fully integrated quantum cryptography system, where compact design, as well as high generation speed, are needed. | ||||
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ISSN | 1742-6588 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | Approved | no | |||
Call Number | Serial | 1178 | |||
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Author | Venediktov, I. O.; Elezov, M. S.; Prokhodtsov, A. I.; Kovalyuk, V. V.; An, P. P.; Golikov, A. D.; Shcherbatenko, M. L.; Sych, D. V.; Goltsman, G. N. | ||||
Title | Study of microheater’s phase modulation for on-chip Kennedy receiver | Type | Conference Article | ||
Year | 2020 | Publication | J. Phys.: Conf. Ser. | Abbreviated Journal | J. Phys.: Conf. Ser. |
Volume | 1695 | Issue | Pages | 012117 | |
Keywords | Mach-Zehnder interferometers, MZI | ||||
Abstract | In this work we describe phase modulators for several Mach-Zehnder interferometers (MZI) on silicon nitride platform for telecomm wavelength (1550 nm). We obtained current-voltage and phase-voltage curves for these modulators. MZI are needed for experimental realisation of various quantum receivers that can distinguish weak coherent states of light with extremely low error. Thermo-optical (TO) modulation is ensured by microheaters on one of the arms of MZI, which enables the change of the refractive index of the material with temperature. This approach allows to apply the necessary voltage to the golden microheaters to obtain the required phase change. For the on-chip microheaters we demonstrate the dependence of the phase shift on the voltage applied to our on-chip microheaters. | ||||
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ISSN | 1742-6588 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | Approved | no | |||
Call Number | Serial | 1179 | |||
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Author | Elmanov, I.; Sardi, F.; Xia, K.; Kornher, T.; Kovalyuk, V.; Prokhodtsov, A.; An, P.; Kuzin, A.; Elmanova, A.; Goltsman, G.; Kolesov, R. | ||||
Title | Development of focusing grating couplers for lithium niobate on insulator platform | Type | Conference Article | ||
Year | 2020 | Publication | J. Phys.: Conf. Ser. | Abbreviated Journal | J. Phys.: Conf. Ser. |
Volume | 1695 | Issue | Pages | 012127 | |
Keywords | grating couplers, lithium niobat | ||||
Abstract | In this paper, we fabricate and experimentally study focusing grating couplers for lithium niobate on an insulator photonic platform. The transmittance of a waveguide equipped with in- and out-couplers with respect to the grating period is measured with and without silicon dioxide cladding applied. Our results show the influence of silicon dioxide cladding on the efficiency and the central wavelength of grating couplers and can be used to improve grating coupling efficiency. Our study is supported by numerical simulations. | ||||
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ISSN | 1742-6588 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | Approved | no | |||
Call Number | Serial | 1180 | |||
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Author | Zubkova, E.; Golikov, A.; An, P.; Kovalyuk, V.; Korneev, A.; Ferrari, S.; Pernice, W.; Goltsman, G. | ||||
Title | CWDM demultiplexer using anti-reflection, contra-directional couplers based on silicon nitride rib waveguide | Type | Conference Article | ||
Year | 2019 | Publication | J. Phys.: Conf. Ser. | Abbreviated Journal | J. Phys.: Conf. Ser. |
Volume | 1410 | Issue | Pages | 012179 | |
Keywords | coarse wavelength-division multiplexing, Si3N4 rib waveguide | ||||
Abstract | We report on the development and fabrication of a 9-channel coarse wavelength-division multiplexing for telecommunication wavelengths (1550 nm) using anti-reflection contra-directional couplers, based on silicon nitride (Si3N4) rib waveguide. The transmitted and reflected spectrum in each channel of the demultiplexer were measured. The average full width at half maximum of the transmitted (reflected) spectra is about 3 nm. | ||||
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ISSN | 1742-6588 | ISBN | Medium | ||
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Notes | Approved | no | |||
Call Number | Serial | 1183 | |||
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