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Author |
Килин, С. Я. |
Title |
Квантовая информация |
Type |
Journal Article |
Year |
1999 |
Publication |
Успехи физических наук |
Abbreviated Journal |
УФН |
Volume |
169 |
Issue |
5 |
Pages |
507-527 |
Keywords |
quantum cryptography; QKD, BB84 |
Abstract |
Новое направление физики – квантовая информация – возникло на стыке квантовой механики, оптики, теории относительности и программирования, дискретной математики, лазерной физики и спектроскопии и включает в себя вопросы квантовых вычислений, квантовых компьютеров, квантовой телепортации и квантовой криптографии, проблемы декогеренции и спектроскопии одиночных молекул и примесных центров. Сообщается о некоторых новых результатах в этой быстро развивающейся области исследований. |
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RPLAB @ gujma @ |
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732 |
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Il'in, K. S.; Currie, M.; Lindgren, M.; Milostnaya, I. I.; Verevkin, A. A.; Gol'tsman, G. N.; Sobolewski, R. |
Title |
Quantum efficiency and time-domain response of superconducting NbN hot-electron photodetectors |
Type |
Journal Article |
Year |
1999 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
9 |
Issue |
2 |
Pages |
3338-3341 |
Keywords |
NbN SSPD, SNSPD |
Abstract |
We report our studies on the response of ultrathin superconducting NbN hot-electron photodetectors. We have measured the photoresponse of few-nm-thick, micron-size structures, which consisted of single and multiple microbridges, to radiation from the continuous-wave semiconductor laser and the femtosecond Ti:sapphire laser with the wavelength of 790 nm and 400 nm, respectively. The maximum responsivity was observed near the film's superconducting transition with the device optimally current-biased in the resistive state. The responsivity of the detector, normalized to its illuminated area and the coupling factor, was 220 A/W(3/spl times/10/sup 4/ V/W), which corresponded to a quantum efficiency of 340. The responsivity was wavelength independent from the far infrared to the ultraviolet range, and was at least two orders of magnitude higher than comparable semiconductor optical detectors. The time constant of the photoresponse signal was 45 ps, when was measured at 2.15 K in the resistive (switched) state using a cryogenic electro-optical sampling technique with subpicosecond resolution. The obtained results agree very well with our calculations performed using a two-temperature model of the electron heating in thin superconducting films. |
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1051-8223 |
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1566 |
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Author |
Il'in, K. S.; Gol'tsman, G. N.; Voronov, B. M.; Sobolewski, Roman |
Title |
Characterization of the electron energy relaxation process in NbN hot-electron devices |
Type |
Conference Article |
Year |
1999 |
Publication |
Proc. 10th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 10th Int. Symp. Space Terahertz Technol. |
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Issue |
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Pages |
390-397 |
Keywords |
HEB mixers, SSPD, SNSPD, NbN films, Nb films |
Abstract |
We report on transient measurements of electron energy relaxation in NbN films with 300-fs time resolution. Using an electro-optic sampling technique, we have studied the photoresponse of 3.5-nm-thick NbN films deposited on sapphire substrates and exposed to 100-fs-wide optical pulses. Our experimental data analysis was based on the two-temperature model and has shown that in our films at the superconducting transition 10.5 K the inelastic electron-phonon scattering time was about (111}+-__.2) ps. This response time indicated that the maximum intermediate-frequency band of a NbN hot-electron phonon-cooled mixer should reach (16+41-3) GHz if one eliminates the bolometric phonon-heating effect. We have suggested several ways to increase the effectiveness of phonon cooling to achieve the above intrinsic value of the NbN mixer bandwidth. |
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1576 |
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Schubert, J.; Semenov, A.; Gol'tsman, G.; Hübers, H.-W.; Schwaab, G.; Voronov, B.; Gershenzon, E. |
Title |
Noise temperature of an NbN hot-electron bolometric mixer at frequencies from 0.7 THz to 5.2 THz |
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Journal Article |
Year |
1999 |
Publication |
Supercond. Sci. Technol. |
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Volume |
12 |
Issue |
11 |
Pages |
748-750 |
Keywords |
NbN HEB mixers |
Abstract |
We report on noise temperature measurements of an NbN phonon-cooled hot-electron bolometric mixer in the terahertz frequency range. The devices were 3 nm thick films with in-plane dimensions 1.7 × 0.2 µm2 and 0.9 × 0.2 µm2 integrated in a complementary logarithmic-spiral antenna. Measurements were performed at seven frequencies ranging from 0.7 THz to 5.2 THz. The measured DSB noise temperatures are 1500 K (0.7 THz), 2200 K (1.4 THz), 2600 K (1.6 THz), 2900 K (2.5 THz), 4000 K (3.1 THz), 5600 K (4.3 THz) and 8800 K (5.2 THz). |
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298 |
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Schubert, J.; Semenov, A.; Gol'tsman, G.; Hübers, H.-W.; Schwaab, G.; Voronov, B.; Gershenzon, E. |
Title |
Noise temperature and sensitivity of a NbN hot-electron mixer at frequencies from 0.7 THz to 5.2 THz |
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Conference Article |
Year |
1999 |
Publication |
Proc. 10th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 10th Int. Symp. Space Terahertz Technol. |
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Issue |
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Pages |
190-199 |
Keywords |
NbN HEB mixers |
Abstract |
We report on noise temperature measurements of a NbN phonon-cooled hot-electron bolometric mixer at different bias regimes. The device was a 3 nm thick bridge with in-plane dimensions of 1.7 x 0.2 gm 2 integrated in a complementary logarithmic spiral antenna. Measurements were performed at frequencies ranging from 0.7 THz up to 5.2 THz. The measured DSB noise temperatures are 1500 K (0.7 THz), 2200 K (1.4 THz), 2600 K (1.6 THz), 2900 K (2.5 THz), 4000 K (3.1 THz) 5600 K (4.3 THz) and 8800 K (5.2 THz). Two bias regimes are possible in order to achieve low noise temperatures. But only one of them yields sensitivity fluctuations close to the theoretical limit. |
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1573 |
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