| Records |
| Author |
Ovchinnikov, Yu. N.; Varlamov, A. A. |
| Title |
Fluctuation-dissipative phenomena in a narrow superconducting channel carrying current below critical |
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Journal Article |
| Year |
2009 |
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arXiv |
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0910.2659v1 |
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1-4 |
| Keywords |
superconducting nanowire, resistance calculation |
| Abstract |
The theory of current transport in a narrow superconducting channel accounting for thermal fluctuations is developed. These fluctuations result in the appearance of small but finite dissipation in the sample. The value of corresponding voltage is found as the function of temperature (close to transition temperature) and arbitrary bias current. It is demonstrated that the value of the activation energy (exponential factor in the Arrenius law) when current approaches to the critical one is proportional to (1-J/Jc)^(5/4). This result is in concordance with the one for the affine phenomenon of the Josephson current decay due to the thermal phase fluctuations, where the activation energy proportional (1-J/J_c)^(3/2)(the difference in the exponents is related to the additional current dependence of the order parameter). Found dependence of the activation energy on current explains the enormous discrepancy between the theoretically predicted before and the experimentally observed broadening of the resistive transition. |
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arXiv:0910.2659v1; 4 pages, 3 figures |
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931 |
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| Author |
Esteban, Eduin; Serna, Hernandez |
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Quantum key distribution protocol with private-public key |
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Journal Article |
| Year |
2009 |
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arXiv |
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arXiv |
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3 |
| Keywords |
quantum cryptography; QKD; protocol |
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A quantum cryptographic protocol based in public key cryptography combinations and private key cryptography is presented. Unlike the BB84 protocol 1 and its many variants 2,3 two quantum channels are used. The present research does not make reconciliation mechanisms of information to derive the key. A three related system of key distribution are described. |
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arXiv: 0908.2146 |
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RPLAB @ gujma @ |
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756 |
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Venkatasubramanian, Chandrasekaran; Cabarcos, Orlando M.; Allara, David L. Horn, Mark W.; Ashok, S. |
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Correlation of temperature response and structure of annealed VOx thin films for IR detector applications |
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Journal Article |
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2009 |
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J. Vac. Sci. Technol. A |
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27 |
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4 |
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6 |
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Annealing |
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The effects of thermal annealing on vanadium oxide (VOx) thin films prepared by pulsed-dc magnetron sputtering were studied to explore methods of improving the efficiency of uncooled IR imaging microbolometers, particularly with respect to maximizing the temperature coefficients of resistance (TCR) (typically ~2%) while minimizing resistivity values (typically 0.05–5 Ω cm). Since high TCR values are usually associated with high resistivities, the experiments were designed to find processing conditions that provide an optimal balance in these properties and to then determine the underlying structural correlations which would enable rational design of thin films for this specific application. VOx films of different compositions were deposited by pulsed-dc reactive sputtering from a vanadium target at different oxygen flow rates. The deposited films were further modified by annealing in inert (nitrogen) and oxidizing (oxygen) atmospheres at four different temperatures for 10, 20, or 30 min at a time. The resistivities of the as-deposited films ranged from 0.2 to 13 Ω cm and the TCR values varied from –1.6% to –2.2%. Depending on the exact annealing conditions, several orders of magnitude change in resistance and significant variations in TCR were observed. Optimal results were obtained with annealing in a nitrogen atmosphere. Structural characterization by x-ray diffraction, field emission scanning electron microscopy, atomic force microscopy, and Raman spectroscopy indicated changes in the film crystallinity and phase for annealing conditions over 300 °C with the onset and extent of the changes dependent on which annealing atmosphere was used. |
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Annealing |
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RPLAB @ gujma @ |
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690 |
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Treuttel, J.; Thomas, B.; Maestrini, A.; Wang, H.; Alderman, B.; Siles, J.V.; Davis, S.; Narhi, T. |
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A 380 GHz sub-harmonic mixer using MMIC foundry based Schottky diodes transferred onto quartz substrate |
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Conference Article |
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2009 |
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Proc. 20th Int. Symp. Space Terahertz Technol. |
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Schottky |
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Charlottesville, Virginia, USA |
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586 |
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Meledin, Denis; Pavolotsky, Alexey; Desmaris, Vincent.; Lapkin, Igor; Risacher, Christophe; Perez, Victor; Henke, Douglas; Nystrom, Olle; Sundin, Erik; Dochev, Dimitar; Pantaleev, Miroslav; Fredrixon, Mathias; Strandberg, Magnus; Voronov, Boris; Goltsman, Gregory; Belitsky, Victor |
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A 1.3-THz balanced waveguide HEB mixer for the APEX telescope |
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Journal Article |
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2009 |
Publication |
IEEE Trans. Microw. Theory Techn. |
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57 |
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1 |
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89-98 |
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HEB, mixer, waveguide, balanced, NbN |
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In this paper, we report about the development, fabrication, and characterization of a balanced waveguide hot electron bolometer (HEB) receiver for the Atacama Pathfinder EXperiment telescope covering the frequency band of 1.25–1.39 THz. The receiver uses a quadrature balanced scheme and two HEB mixers, fabricated from 4- to 5-nm-thick NbN film deposited on crystalline quartz substrate with an MgO buffer layer in between. We employed a novel micromachining method to produce all-metal waveguide parts at submicrometer accuracy (the main-mode waveguide dimensions are 90×180 μm). We present details on the mixer design and measurement results, including receiver noise performance, stability and “first-light†at the telescope site. The receiver yields a double-sideband noise temperature averaged over the RF band below 1200 K, and outstanding stability with a spectroscopic Allan time more than 200 s. |
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0018-9480 |
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no |
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RPLAB @ lobanovyury @ |
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554 |
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