Records |
Author |
Smirnov, K.; Divochiy, A.; Vakhtomin, Y.; Morozov, P.; Zolotov, P.; Antipov, A.; Seleznev, V. |
Title |
NbN single-photon detectors with saturated dependence of quantum efficiency |
Type |
Journal Article |
Year |
2018 |
Publication |
Supercond. Sci. Technol. |
Abbreviated Journal |
Supercond. Sci. Technol. |
Volume |
31 |
Issue |
3 |
Pages |
035011 (1 to 8) |
Keywords |
NbN SSPD, SNSPD |
Abstract |
The possibility of creating NbN superconducting single-photon detectors with saturated dependence of quantum efficiency (QE) versus normalized bias current was investigated. It was shown that the saturation increases for the detectors based on finer films with a lower value of Rs300/Rs20. The decreasing of Rs300/Rs20 was related to the increasing influence of quantum corrections to conductivity of superconductors and, in turn, to the decrease of the electron diffusion coefficient. The best samples have a constant value of system QE 94% at Ib/Ic ~ 0.8 and wavelength 1310 nm. |
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0953-2048 |
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1232 |
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Author |
Smirnov, K. V.; Divochiy, A. V.; Vakhtomin, Y. B.; Sidorova, M. V.; Karpova, U. V.; Morozov, P. V.; Seleznev, V. A.; Zotova, A. N.; Vodolazov, D. Y. |
Title |
Rise time of voltage pulses in NbN superconducting single photon detectors |
Type |
Journal Article |
Year |
2016 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
Volume |
109 |
Issue |
5 |
Pages |
052601 |
Keywords |
SSPD, SNSPD |
Abstract |
We have found experimentally that the rise time of voltage pulse in NbN superconducting single photon detectors increases nonlinearly with increasing the length of the detector L. The effect is connected with dependence of resistance of the detector Rn, which appears after photon absorption, on its kinetic inductance Lk and, hence, on the length of the detector. This conclusion is confirmed by our calculations in the framework of two temperature model.
D.Yu.V. acknowledges the support from the Russian Foundation for Basic Research (Project No. 15-42-02365). K.V.S. acknowledges the financial support from the Ministry of Education and Science of the Russian Federation (Contract No. 3.2655.2014/K). |
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ISSN |
0003-6951 |
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no |
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Serial |
1236 |
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Author |
Sidorova, M.; Semenov, Alexej D.; Hübers, H.-W.; Ilin, K.; Siegel, M.; Charaev, I.; Moshkova, M.; Kaurova, N.; Goltsman, G. N.; Zhang, X.; Schilling, A. |
Title |
Electron energy relaxation in disordered superconducting NbN films |
Type |
Journal Article |
Year |
2020 |
Publication |
Phys. Rev. B |
Abbreviated Journal |
Phys. Rev. B |
Volume |
102 |
Issue |
5 |
Pages |
054501 (1 to 15) |
Keywords |
NbN SSPD, SNSPD, HEB, bandwidth, relaxation time |
Abstract |
We report on the inelastic-scattering rate of electrons on phonons and relaxation of electron energy studied by means of magnetoconductance, and photoresponse, respectively, in a series of strongly disordered superconducting NbN films. The studied films with thicknesses in the range from 3 to 33 nm are characterized by different Ioffe-Regel parameters but an almost constant product qTl (qT is the wave vector of thermal phonons and l is the elastic mean free path of electrons). In the temperature range 14–30 K, the electron-phonon scattering rates obey temperature dependencies close to the power law 1/τe−ph∼Tn with the exponents n≈3.2–3.8. We found that in this temperature range τe−ph and n of studied films vary weakly with the thickness and square resistance. At 10 K electron-phonon scattering times are in the range 11.9–17.5 ps. The data extracted from magnetoconductance measurements were used to describe the experimental photoresponse with the two-temperature model. For thick films, the photoresponse is reasonably well described without fitting parameters, however, for thinner films, the fit requires a smaller heat capacity of phonons. We attribute this finding to the reduced density of phonon states in thin films at low temperatures. We also show that the estimated Debye temperature in the studied NbN films is noticeably smaller than in bulk material. |
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2469-9950 |
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1266 |
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Author |
Shcherbatenko, M. L.; Elezov, M. S.; Goltsman, G. N.; Sych, D. V. |
Title |
Sub-shot-noise-limited fiber-optic quantum receiver |
Type |
Journal Article |
Year |
2020 |
Publication |
Phys. Rev. A |
Abbreviated Journal |
Phys. Rev. A |
Volume |
101 |
Issue |
3 |
Pages |
032306 (1 to 5) |
Keywords |
SSPD mixer, SNSPD |
Abstract |
We experimentally demonstrate a quantum receiver based on the Kennedy scheme for discrimination between two phase-modulated weak coherent states. The receiver is assembled entirely from standard fiber-optic elements and operates at a conventional telecom wavelength of 1.55 μm. The local oscillator and the signal are transmitted through different optical fibers, and the displaced signal is measured with a high-efficiency superconducting nanowire single-photon detector. We show the discrimination error rate is two times below that of a shot-noise-limited receiver with the same system detection efficiency. |
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2469-9926 |
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1268 |
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Author |
Elezov, M.; Ozhegov, R.; Goltsman, G.; Makarov, V. |
Title |
Countermeasure against bright-light attack on superconducting nanowire single-photon detector in quantum key distribution |
Type |
Journal Article |
Year |
2019 |
Publication |
Opt. Express |
Abbreviated Journal |
Opt. Express |
Volume |
27 |
Issue |
21 |
Pages |
30979-30988 |
Keywords |
SSPD, SNSPD |
Abstract |
We present an active anti-latching system for superconducting nanowire single-photon detectors. We experimentally test it against a bright-light attack, previously used to compromise security of quantum key distribution. Although our system detects continuous blinding, the detector is shown to be partially blindable and controllable by specially tailored sequences of bright pulses. Improvements to the countermeasure are suggested. |
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English |
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Edition |
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ISSN |
1094-4087 |
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Notes |
PMID:31684339 |
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no |
Call Number |
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Serial |
1275 |
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