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Author |
Risacher, C.; Meledin, D.; Belitsky, V.; Bergman, P. |
Title |
First 1.3 THz observations at the APEX telescope |
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Conference Article |
Year |
2009 |
Publication |
Proc. 20th Int. Symp. Space Terahertz Technol. |
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54-61 |
Keywords |
balanced HEB mixer noise temperature APEX telescope stability Allan variance aperture efficiency |
Abstract |
The Atacama Pathfinder EXperiment (APEX) 12m telescope is operating on the Llano Chajnantor, Chile, since 2003 and a set of state of the art sub-millimeter receivers have been installed for frequencies spanning from 150 GHz to 1500 GHz. In 2008, a balanced 1.3 THz Hot Electron Bolometer (HEB) receiver was installed for the atmospheric window 1250-1380 GHz. This instrument is part of a 4-channel receiver cryostat with the other channels being 211-275 GHz, 275-370 GHz and 380-500 GHz Sideband Separating (SSB) SIS receivers. This paper presents the first observations obtained so far with the 1.3 THz band during its first months of operation. The sky measurements were taken during opportunistic commissioning and science verification phases, when the weather conditions were sufficiently good with a Precipitable Water Vapor (PWV) below 0.25 mm, which was the case only a few nights during these months. We present the first observations of the molecular transition CO J=(11-10) line on different sources such as Orion-FIR4, CW-Leo and SgrB2(M). We describe the many challenges and difficulties encountered for achieving successful THz observations from a large sub-millimeter ground-based telescope. |
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619 |
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Korneev, A.; Kovalyuk, V.; Ferrari, S.; Kahl, O.; Pernice, W.; An, P.; Golikov, A.; Zubkova, E.; Goltsman, G. |
Title |
Superconducting Single-Photon Detectors for Integrated Nanophotonics Circuits |
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Conference Article |
Year |
2017 |
Publication |
16th ISEC |
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16th ISEC |
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1-3 |
Keywords |
SSPD, SNSPD |
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We present an overview of our recent achievements in integration of superconducting nanowire single-photon detectors SNSPD with dielectric optical waveguides. We are able to produce complex nanophotonics integrated circuits containing optical elements and photon detector on single chip thus producing a compact integrated platform for quantum optics applications. |
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8314200 |
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1200 |
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Zubkova, E.; An, P.; Kovalyuk, V.; Korneev, A.; Goltsman, G. |
Title |
Integrated Bragg waveguides as an efficient optical notch filter on silicon nitride platform |
Type |
Conference Article |
Year |
2017 |
Publication |
Proc. SPBOPEN |
Abbreviated Journal |
Proc. SPBOPEN |
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Pages |
449-450 |
Keywords |
Bragg waveguides |
Abstract |
We modeled and fabricated integrated optical Bragg waveguides on a silicon nitride (Si3N4) platform. Transmission spectra of the integrated notch filter has been measured and attenuation at the desired wavelength of 1550 nm down to -43 dB was observed. |
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St. Petersburg, Russia |
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Duplicated as 1141 |
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1257 |
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Kovaluyk, V.; Lazarenko, P.; Kozyukhin, S.; An, P.; Prokhodtsov, A.; Goltsman, G.; Sherchenkov, A. |
Title |
Influence of the phase state of Ge2Sb2Te5 thin cover on the parameters of the optical waveguide structures |
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Abstract |
Year |
2019 |
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Proc. Amorphous and Nanostructured Chalcogenides |
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Proc. Amorphous and Nanostructured Chalcogenides |
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47-48 |
Keywords |
optical waveguides |
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The fast switching time of Ge-Sb-Te thin films between amorphous and crystalline states initiated by laser beam as well as significant change of their optical properties and the preservation of metastable states for tens of years open wide perspectives for the application of these materials to fully optical devices [1], including high-speed optical memory [2]. Here we study optical properties of the Ge2Sb2Te5 (GST225) thin films integrated with on-chip silicon nitride O-ring resonator. The rib waveguide of the resonator was formed the first stage of e-beam lithography and subsequent reactive-ion etching. We used the second stage of e-beam lithography combining with lift-off method for the formation of GST225 active region on the resonator ring surface. The amorphous GST225 thin films were prepared by magnetron sputtering, and were capped by thin silicon oxide on their tops. The length of the GST225 active region varied from 0.1 to 20 μ m. Crystallization of amorphous thin films was carried out at the temperature of 400 °C for 30 minutes. Auger electron spectroscopy and transmission electron microscopy were used for studying composition and structure of investigated GST225thin films, respectively. It was observed that crystallization of amorphous GST225 film lead to a decrease of the optical power, transmitted through the waveguide. Comparison of the optical transmittance of O-ring resonators before and after the GST225 deposition allowed to identify the change in the Q-factor and the wavelength peak shift. This can be explained by the differences of the complex refractive indexes of GST225 thin films in the amorphous and crystalline states. From the measurement data, the GST225 effective refractive index was extracted depending on the ring waveguide width of the resonator for a telecommunication wavelength of 1550 nm. |
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Technical University of Moldova |
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1281 |
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Arutyunov, K. Y.; Ramos-Álvarez, A.; Semenov, A. V.; Korneeva, Y. P.; An, P. P.; Korneev, A. A.; Murphy, A.; Bezryadin, A.; Gol’tsman, G. N. |
Title |
Quasi-1-dimensional superconductivity in highly disordered NbN nanowires |
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Miscellaneous |
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2016 |
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arXiv |
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narrow NbN nanowires, BCS |
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The topic of superconductivity in strongly disordered materials has attracted a significant attention. In particular vivid debates are related to the subject of intrinsic spatial inhomogeneity responsible for non-BCS relation between the superconducting gap and the pairing potential. Here we report experimental study of electron transport properties of narrow NbN nanowires with effective cross sections of the order of the debated inhomogeneity scales. We find that conventional models based on phase slip concept provide reasonable fits for the shape of the R(T) transition curve. Temperature dependence of the critical current follows the text-book Ginzburg-Landau prediction for quasi-one-dimensional superconducting channel Ic~(1-T/Tc)^3/2. Hence, one may conclude that the intrinsic electronic inhomogeneity either does not exist in our structures, or, if exist, does not affect their resistive state properties. |
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Duplicated as 1332 |
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1338 |
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Kardakova, A. I.; Coumou, P. C. J. J.; Finkel, M. I.; Morozov, D. V.; An, P. P.; Goltsman, G. N.; Klapwijk, T. M. |
Title |
Electron–phonon energy relaxation time in thin strongly disordered titanium nitride films |
Type |
Journal Article |
Year |
2015 |
Publication |
IEEE Trans. Appl. Supercond. |
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IEEE Trans. Appl. Supercond. |
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25 |
Issue |
3 |
Pages |
1-4 |
Keywords |
TiN MKID |
Abstract |
We have measured the energy relaxation times from the electron bath to the phonon bath in strongly disordered TiN films grown by atomic layer deposition. The measured values of τ eph vary from 12 to 91 ns. Over a temperature range from 3.4 to 1.7 K, they follow T -3 temperature dependence, which are consistent with values of τ eph reported previously for sputtered TiN films. For the most disordered film, with an effective elastic mean free path of 0.35 nm, we find a faster relaxation and a stronger temperature dependence, which may be an additional indication of the influence of strong disorder on a superconductor. |
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1051-8223 |
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1296 |
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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 |
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Journal Article |
Year |
2016 |
Publication |
Nanotechnol. |
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Nanotechnol. |
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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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English |
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0957-4484 |
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PMID:27782000 |
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1332 |
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Chuprina, I. N.; An, P. P.; Zubkova, E. G.; Kovalyuk, V. V.; Kalachev, A. A.; Gol'tsman, G. N. |
Title |
Optimisation of spontaneous four-wave mixing in a ring microcavity |
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Conference Article |
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2017 |
Publication |
J. Phys.: Conf. Ser. |
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J. Phys.: Conf. Ser. |
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47 |
Issue |
10 |
Pages |
887-891 |
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ring microcavity |
Abstract |
Abstract. A theory of spontaneous four-wave mixing in a ring microcavity is developed. The rate of emission of biphotons for pulsed and monochromatic pumping with allowance for the disper- sion of group velocities is analytically calculated. In the first case, pulses in the form of an increasing exponential are considered, which are optimal for excitation of an individual resonator mode. The behaviour of the group velocity dispersion as a function of the width and height of the waveguide is studied for a specific case of a ring microcavity made of silicon nitride. The results of the numeri- cal calculation are in good agreement with the experimental data. The ring microcavity is made of two types of waveguides: com- pletely etched and half etched. It is found that the latter allow for better control over the parameters in the manufacturing process, making them more predictable. |
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RPLAB @ kovalyuk @ |
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1142 |
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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 |
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Journal Article |
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2013 |
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J. Opt. Technol. |
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J. Opt. Technol. |
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80 |
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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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1172 |
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Kooi, J. W.; Baselmans, J. J. A.; Hajenius, M.; Gao, J. R.; Klapwijk, T. M.; Dieleman, P.; Baryshev, A.; de Lange, G. |
Title |
IF impedance and mixer gain of NbN hot electron bolometers |
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Journal Article |
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2007 |
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J. Appl. Phys. |
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101 |
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4 |
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044511 |
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0021-8979 |
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RPLAB @ s @ |
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445 |
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