Home | [1–10] << 11 12 13 14 15 16 17 18 19 20 >> [21–30] |
Records | |||||
---|---|---|---|---|---|
Author | Gol’tsman, G. N. | ||||
Title | The “Millimetron” project, a future space telescope mission | Type | Abstract | ||
Year | 2007 | Publication | Proc. 18th Int. Symp. Space Terahertz Technol. | Abbreviated Journal | Proc. 18th Int. Symp. Space Terahertz Technol. |
Volume | Issue | Pages | 255 | ||
Keywords | Millimetron space observatory, VLBI | ||||
Abstract | The goal of the Millimetron project is to develop a space observatory operating in the millimeter, sub-millimeter and infrared wavelength ranges using a 12-m actively cooled telescope in a single-dish mode and as an interferometer with the space-ground and space-space baselines (the later after the launch of the second identical space telescope). The Millimetron’s main reflector and other optics will be cooled down to 4K thus enabling astronomical observations with super high sensitivity in MM and subMM (down to nanoJansky level). Heterodyne observations in an interferometer mode at frequencies 0.1-1 THz will provide super high angular resolution. The main instruments, planned to be installed are wide-range imaging arrays, radiometers with spectrometers and polarimeters, VLBI heterodyne receivers, and Mikelson type interferometer devices. Wide-range MM and subMM imaging arrays and spectrometers will be based on a superconducting hot electron direct detectors with Andreev mirrors operating at 0.1 K. Such detectors are the best candidates to reach the noise equivalent power level of 10 -19 -10 -20 W/√Hz. Heterodyne receivers will be both SIS based superconducting integrated receiver with flux-flow oscillator as LO (0.1-0.9 THz range) and HEB based receivers using multiplied Gunn oscillator as LO for 1-2 THz range and quantum cascade lasers as LO for 2-5 THz range. For observations in middle IR region there will be installed large arrays of superconducting single photon detectors, providing imaging with very high dynamic range and ultimate sensitivity. | ||||
Address | |||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Summary Language | Original Title | |||
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | ISBN | Medium | |||
Area | Expedition | Conference | |||
Notes | Approved | no | |||
Call Number | Serial | 1422 | |||
Permanent link to this record | |||||
Author | Bell, M.; Sergeev, A.; Mitin, V.; Bird, J.; Verevkin, A.; Gol’tsman, G. | ||||
Title | One-dimensional resistive states in quasi-two-dimensional superconductors: Experiment and theory | Type | Journal Article | ||
Year | 2007 | Publication | Phys. Rev. B | Abbreviated Journal | Phys. Rev. B |
Volume | 76 | Issue | 9 | Pages | 094521 (1 to 5) |
Keywords | uasi-two-dimensional superconductors, NbN | ||||
Abstract | We investigate competition between one- and two-dimensional topological excitations—phase slips and vortices—in the formation of resistive states in quasi-two-dimensional superconductors in a wide temperature range below the mean-field transition temperature TC0. The widths w=100nm of our ultrathin NbN samples are substantially larger than the Ginzburg-Landau coherence length ξ=4nm, and the fluctuation resistivity above TC0 has a two-dimensional character. However, our data show that the resistivity below TC0 is produced by one-dimensional excitations—thermally activated phase slip strips (PSSs) overlapping the sample cross section. We also determine the scaling phase diagram, which shows that even in wider samples the PSS contribution dominates over vortices in a substantial region of current and/or temperature variations. Measuring the resistivity within 7 orders of magnitude, we find that the quantum phase slips can only be essential below this level. | ||||
Address | |||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Summary Language | Original Title | |||
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1098-0121 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | Approved | no | |||
Call Number | Serial | 1423 | |||
Permanent link to this record | |||||
Author | Gao, J. R.; Hajenius, M.; Tichelaar, F. D.; Klapwijk, T. M.; Voronov, B.; Grishin, E.; Gol’tsman, G.; Zorman, C. A.; Mehregany, M. | ||||
Title | Monocrystalline NbN nanofilms on a 3C-SiC∕Si substrate | Type | Journal Article | ||
Year | 2007 | Publication | Appl. Phys. Lett. | Abbreviated Journal | Appl. Phys. Lett. |
Volume | 91 | Issue | 6 | Pages | 062504 (1 to 3) |
Keywords | NbN films, nanofilms | ||||
Abstract | The authors have realized NbN (100) nanofilms on a 3C-SiC (100)/Si(100) substrate by dc reactive magnetron sputtering at 800°C. High-resolution transmission electron microscopy (HRTEM) is used to characterize the films, showing a monocrystalline structure and confirming epitaxial growth on the 3C-SiC layer. A film ranging in thickness from 3.4to4.1nm shows a superconducting transition temperature of 11.8K, which is the highest reported for NbN films of comparable thickness. The NbN nano-films on 3C-SiC offer a promising alternative to improve terahertz detectors. For comparison, NbN nanofilms grown directly on Si substrates are also studied by HRTEM. The authors acknowledge S. V. Svetchnikov at National Centre for HRTEM at Delft, who prepared the specimens for HRTEM inspections. This work was supported by the EU through RadioNet and INTAS. |
||||
Address | |||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Summary Language | Original Title | |||
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 0003-6951 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | Approved | no | |||
Call Number | Serial | 1425 | |||
Permanent link to this record | |||||
Author | Kerman, A. J.; Dauler, E. A.; Yang, J. K. W.; Rosfjord, K. M.; Anant, V.; Berggren, K. K.; Gol’tsman, G. N.; Voronov, B. M. | ||||
Title | Constriction-limited detection efficiency of superconducting nanowire single-photon detectors | Type | Journal Article | ||
Year | 2007 | Publication | Appl. Phys. Lett. | Abbreviated Journal | Appl. Phys. Lett. |
Volume | 90 | Issue | 10 | Pages | 101110 (1 to 3) |
Keywords | SSPD, SNSPD | ||||
Abstract | We investigate the source of the large variations in the observed detection efficiencies of superconducting nanowire single-photon detectors between many nominally identical devices. Through both electrical and optical measurements, we infer that these variations arise from “constrictions:” highly localized regions of the nanowires where the effective cross-sectional area for superconducting current is reduced. These constrictions limit the bias-current density to well below its critical value over the remainder of the wire, and thus prevent the detection efficiency from reaching the high values that occur in these devices when they are biased near the critical current density. This work is sponsored by the United States Air Force under Contract No. FA8721-05-C-0002. |
||||
Address | |||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Summary Language | Original Title | |||
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 0003-6951 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | Approved | no | |||
Call Number | Serial | 1433 | |||
Permanent link to this record | |||||
Author | Słysz, W.; Wegrzecki, M.; Bar, J.; Grabiec, P.; Górska, M.; Zwiller, V.; Latta, C.; Böhi, P.; Pearlman, A.J.; Cross, A.S.; Pan, D.; Kitaygorsky, J.; Komissarov, I.; Verevkin, A.; Milostnaya, I.; Korneev, A.; Minayeva, O.; Chulkova, G.; Smirnov, K.; Voronov, B.; Gol’tsman, G.N.; Sobolewski, R. | ||||
Title | Fibre-coupled, single photon detector based on NbN superconducting nanostructures for quantum communications | Type | Journal Article | ||
Year | 2007 | Publication | J. Modern Opt. | Abbreviated Journal | J. Modern Opt. |
Volume | 54 | Issue | 2-3 | Pages | 315-326 |
Keywords | NbN SSPD, SNSPD | ||||
Abstract | We present a novel, two-channel, single photon receiver based on two fibre-coupled, NbN, superconducting, single photon detectors (SSPDs). The SSPDs are nanostructured superconducting meanders and are known for ultrafast and efficient detection of visible-to-infrared photons. Coupling between the NbN detector and optical fibre was achieved using a micromechanical photoresist ring placed directly over the SSPD, holding the fibre in place. With this arrangement, we obtained coupling efficiencies up to ∼30%. Our experimental results showed that the best receiver had a near-infrared system quantum efficiency of 0.33% at 4.2 K. The quantum efficiency increased exponentially with the photon energy increase, reaching a few percent level for visible-light photons. The photoresponse pulses of our devices were limited by the meander high kinetic inductance and had the rise and fall times of approximately 250 ps and 5 ns, respectively. The receiver's timing jitter was in the 37 to 58 ps range, approximately 2 to 3 times larger than in our older free-space-coupled SSPDs. We stipulate that this timing jitter is in part due to optical fibre properties. Besides quantum communications, the two-detector arrangement should also find applications in quantum correlation experiments. | ||||
Address | |||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Summary Language | Original Title | |||
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 0950-0340 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | Approved | no | |||
Call Number | Serial | 1434 | |||
Permanent link to this record |