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Author Sidorova, M. V.; Kozorezov, A. G.; Semenov, A. V.; Korneev, A. A.; Chulkova, G. M.; Korneeva, Y. P.; Mikhailov, M. Y.; Devizenko, A. Y.; Goltsman, G. N.
Title Non-bolometric bottleneck in electron-phonon relaxation in ultra-thin WSi film Type Miscellaneous
Year 2018 Publication arXiv Abbreviated Journal
Volume Issue Pages
Keywords WSi films, diffusion constant, SSPD, SNSPD
Abstract We developed the model of the internal phonon bottleneck to describe the energy exchange between the acoustically soft ultrathin metal film and acoustically rigid substrate. Discriminating phonons in the film into two groups, escaping and nonescaping, we show that electrons and nonescaping phonons may form a unified subsystem, which is cooled down only due to interactions with escaping phonons, either due to direct phonon conversion or indirect sequential interaction with an electronic system. Using an amplitude-modulated absorption of the sub-THz radiation technique, we studied electron-phonon relaxation in ultrathin disordered films of tungsten silicide. We found an experimental proof of the internal phonon bottleneck. The experiment and simulation based on the proposed model agree well, resulting in tau{e-ph} = 140-190 ps at TC = 3.4 K, supporting the results of earlier measurements by independent techniques.
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Notes Duplicated as 1305 Approved no
Call Number Serial 1341
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Author Vodolazov, D. Y.; Korneeva, Y. P.; Semenov, A. V.; Korneev, A. A.; Goltsman, G. N.
Title Vortex-assisted mechanism of photon counting in a superconducting nanowire single-photon detector revealed by external magnetic field Type Journal Article
Year 2015 Publication Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 92 Issue 10 Pages 104503 (1 to 9)
Keywords SSPD, SNSPD
Abstract We use an external magnetic field to probe the detection mechanism of a superconducting nanowire single-photon detector. We argue that the hot belt model (which assumes partial suppression of the superconducting order parameter Δ across the whole width of the superconducting nanowire after absorption of the photon) does not explain observed weak-field dependence of the photon count rate (PCR) for photons with λ=450nm and noticeable decrease of PCR (with increasing the magnetic field) in a range of the currents for photons with wavelengths λ=450–1200nm. Found experimental results for all studied wavelengths can be explained by the vortex hot spot model (which assumes partial suppression of Δ in the area with size smaller than the width of the nanowire) if one takes into account nucleation and entrance of the vortices to the photon induced hot spot and their pinning by the hot spot with relatively large size and strongly suppressed Δ.
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ISSN 1098-0121 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1343
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Author Elezov, M. S.; Ozhegov, R. V.; Kurochkin, Y. V.; Goltsman, G. N.; Makarov, V. S.; Samartsev, V. V.; Vinogradov, E. A.; Naumov, A. V.; Karimullin, K. R.
Title Countermeasures against blinding attack on superconducting nanowire detectors for QKD Type Conference Article
Year 2015 Publication EPJ Web Conf. Abbreviated Journal EPJ Web Conf.
Volume 103 Issue Pages 10002 (1 to 2)
Keywords SSPD, SNSPD, QKD
Abstract Nowadays, the superconducting single-photon detectors (SSPDs) are used in Quantum Key Distribution (QKD) instead of single-photon avalanche photodiodes. Recently bright-light control of the SSPD has been demonstrated. This attack employed a “backdoor” in the detector biasing technique. We developed the autoreset system which returns the SSPD to superconducting state when it is latched. We investigate latched state of the SSPD and define limit conditions for effective blinding attack. Peculiarity of the blinding attack is a long nonsingle photon response of the SSPD. It is much longer than usual single photon response. Besides, we need follow up response duration of the SSPD. These countermeasures allow us to prevent blind attack on SSPDs for Quantum Key Distribution.
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ISSN 2100-014X ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1352
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Author Samsonova, A. S.; Zolotov, P. I.; Baeva, E. M.; Lomakin, A. I.; Titova, N. A.; Kardakova, A. I.; Goltsman, G. N.
Title Signatures of surface magnetic disorder in niobium films Type Journal Article
Year 2021 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.
Volume 31 Issue 5 Pages 1-5
Keywords Nb films
Abstract We present our studies on the evolution of the normal and superconducting properties with thickness of thin Nb films with a low level of non-magnetic disorder ( kFl≈150 for the thickest film in the set). The analysis of the superconducting behavior points to the presence of magnetic moments, hidden in the native oxide on the surface of Nb films. Using the Abrikosov-Gorkov theory, we obtain the density of surface magnetic moments of 1013 cm −2 , which is in agreement with the previously reported data for Nb films.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume (down) Series Issue Edition
ISSN 1051-8223 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1792
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Author Zhang, W.; Miao, W.; Li, S. L.; Zhou, K. M.; Shi, S. C.; Gao, J. R.; Goltsman, G. N.
Title Measurement of the spectral response of spiral-antenna coupled superconducting hot electron bolometers Type Journal Article
Year 2013 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.
Volume 23 Issue 3 Pages 2300804-2300804
Keywords NbN HEB detector
Abstract Measured spectral response of spiral-antenna coupled superconducting hot electron bolometers (HEBs) often drops dramatically at frequencies that are still within the frequency range of interest (e.g., ~ 5 THz). This is inconsistent with the implied low receiver noise temperatures from the same measurements. To understand this discrepancy, we exhaustively test and calibrate the thermal sources used in Fourier transform spectrometer measurements. We first investigate the absolute emission spectrum of high-pressure Hg arc lamp, then measure the spectral response of two spiral-antenna coupled NbN HEBs with a Martin-Puplett interferometer as spectrometer and 77 K blackbody as broadband signal source. The measured absolute emission spectrum of Hg arc lamp is proportional to frequency, corresponding to an equivalent blackbody temperature of 4000 K at 1 THz, 1500 K at 3 THz, and 800 K at 5 THz, respectively. Measured spectral response of spiral-antenna coupled NbN HEBs, corrected for air absorption, is nearly flat in the frequency range of 0.5-4 THz, consistent with simulated coupling efficiency between HEB and spiral-antenna. These results explain the discrepancy, and prove that spiral-antenna coupled superconducting NbN HEBs work well in a wide frequency range. In addition, this calibration method and these results are broadly applicable to other quasi-optical THz receivers.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume (down) Series Issue Edition
ISSN 1051-8223 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1371
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