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Author Kooi, Jacob Willem
Title (up) Advanced receivers for submillimeter and far infrared astronomy Type Book Whole
Year 2008 Publication University of Groningen Abbreviated Journal RUG
Volume Issue Pages
Keywords HEB, SIS, TES, NEP, noise temperature, IF bandwidth, waveguide, impedance, conversion gain, FTS, integrated array, stability, Allan variance, multi-layer antireflection coating
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Corporate Author Thesis Doctoral thesis
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ISSN ISBN 978-90-367-3653-4 Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 881
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Author Kawano, Yukio; Ishibashi, Koji
Title (up) An on-chip near-field terahertz probe and detector Type Journal Article
Year 2008 Publication Nature Photonics Abbreviated Journal Nature Photon
Volume 2 Issue 10 Pages 618-621
Keywords single molecule, terahertz, THz, near-field, microscopy, imaging, 2DEG, GaAs/AlGaAs, detector, applications
Abstract The advantageous properties of terahertz waves, such as their transmission through objects opaque to visible light, are attracting attention for imaging applications. A promising approach for achieving high spatial resolution is the use of near-field imaging. Although this method has been well established in the visible and microwave regions, it is challenging to perform in the terahertz region. In the terahertz techniques investigated to date, detectors have been located remotely from the probe, which degrades sensitivity, and the influence of far-field waves is unavoidable. Here we present a new integrated detection device for terahertz near-field imaging in which all the necessary detection components — an aperture, a probe and a terahertz detector — are integrated on one semiconductor chip, which is cryogenically cooled. This scheme allows highly sensitive, high-resolution detection of the evanescent field alone and promises new capabilities for high-resolution terahertz imaging.
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ISSN 1749-4885 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 570
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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.
Title (up) APEX Band T2: A 1.25 – 1.39 THz Waveguide Balanced HEB Receiver Type Journal Article
Year 2008 Publication Abbreviated Journal
Volume Issue Pages 181-185
Keywords
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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Notes Approved no
Call Number RPLAB @ atomics90 @ Serial 974
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Author Kopp, Victor I.; Churikov, Victor M.; Genack, Azriel Z.
Title (up) Chiral-fiber gratings sense the environment Type Conference Article
Year 2008 Publication Laser Focus World Abbreviated Journal
Volume 44 Issue 6 Pages 76-79
Keywords chiral fiber gratings, chiral gratings, from chiralphotonics
Abstract The article focuses on the use of chiral fiber gratings in sensing. It discusses the production of chiral optical fibers which are created through twisting fibers. It cites experiments concerning the function of chiral-fiber grating produced by twisting optical fibers. The process and results of the experiments are also discussed in the article.
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Notes Approved no
Call Number Serial 850
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Author Pirandola, Stefano; Mancini, Stefano; Lloyd, Seth; Braunstein, Samuel L.
Title (up) Continuous-variable quantum cryptography using two-way quantum communication Type Journal Article
Year 2008 Publication Nature Physics Abbreviated Journal Nat. Phys.
Volume 4 Issue 9 Pages 726-730
Keywords fromIPMRAS
Abstract Quantum cryptography has recently been extended to continuous-variable systems, such as the bosonic modes of the electromagnetic field possessing continuous degrees of freedom. In particular, several cryptographic protocols have been proposed and experimentally implemented using bosonic modes with Gaussian statistics. These protocols have shown the possibility of reaching very high secret key rates, even in the presence of strong losses in the quantum communication channel. Despite this robustness to loss, their security can be affected by more general attacks where extra Gaussian noise is introduced by the eavesdropper. Here, we show a `hardware solution' for enhancing the security thresholds of these protocols. This is possible by extending them to two-way quantum communication where subsequent uses of the quantum channel are suitably combined. In the resulting two-way schemes, one of the honest parties assists the secret encoding of the other, with the chance of a non-trivial superadditive enhancement of the security thresholds. These results should enable the extension of quantum cryptography to more complex quantum communications.
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Notes Approved no
Call Number RPLAB @ gujma @ Serial 798
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