Омельянук, А. Н., Ильичев, Е. В., & Шевченко, С. Н. (2013). Квантовые когерентные явления в джозефсоновских кубитах. Наукова книга. Киев: ФТИНТ им. Б. И. Верника НАН Украины.
Abstract: Монография посвящена актуальным проблемам физики сверхпроводниковых джозефсоновских кубитов — макроскопических квантовых структур, перспективных элементов квантовых компьютеров. Приведены элементы квантовой механики кубитов, фундаментальные свойства сверхпроводников, физика классических и квантовых джозефсоновских структур. Рассмотрены основные типы сверхпроводниковых кубитов. Изложены результаты экспериментальных и теоретических исследований квантовых когерентных явлений в джозефсоновских кубитах. Рассмотрены спектроскопия энергетичеÂских состояний, осцилляции Раби, эффект Ландау-Зинера, многофотонные переходы в одиночних кубитах и в системах связанных кубитов. Изучено влияние шумов на потоковый кубит и на его классический аналог.
Для специалистов в области теоретической и прикладной физики, сверхпроводниковой микроэлектроники, а также аспирантов и студентов физико-технических специальностей.
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Korneev, A. A., Divochiy, A. V., Vakhtomin, Y. B., Korneeva, Y. P., Larionov, P. A., Manova, N. N., et al. (2013). IR single-photon receiver based on ultrathin NbN superconducting film. Rus. J. Radio Electron., (5).
Abstract: We present our recent results in research and development of superconducting single-photon detector (SSPD). We achieved the following performance improvement: first, we developed and characterized SSPD integrated in optical cavity and enabling its illumination from the face side, not through the substrate, second, we improved the quantum efficiency of the SSPD at around 3 μm wavelength by reduction of the strip width to 40 nm, and, finally, we improved the detection efficiency of the SSPD-based single-photon receiver system up to 20% at 1550 nm and extended its wavelength range beyond 1800 nm by the usage of the fluoride ZBLAN fibres.
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Collins, M. J., Xiong, C., Rey, I. H., Vo, T. D., He, J., Shahnia, S., et al. (2013). Integrated spatial multiplexing of heralded single-photon sources. Nature Communications, .
Abstract: The non-deterministic nature of photon sources is a key limitation for single-photon quantum processors. Spatial multiplexing overcomes this by enhancing the heralded single-photon yield without enhancing the output noise. Here the intrinsic statistical limit of an individual source is surpassed by spatially multiplexing two monolithic silicon-based correlated photon pair sources in the telecommunications band, demonstrating a 62.4% increase in the her- alded single-photon output without an increase in unwanted multipair generation. We further demonstrate the scalability of this scheme by multiplexing photons generated in two waveguides pumped via an integrated coupler with a 63.1% increase in the heralded photon rate. This demonstration paves the way for a scalable architecture for multiplexing many photon sources in a compact integrated platform and achieving efficient two-photon inter- ference, required at the core of optical quantum computing and quantum communication protocols.
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Kardakova, A., Finkel, M., Morozov, D., Kovalyuk, V., An, P., Dunscombe, C., et al. (2013). The electron-phonon relaxation time in thin superconducting titanium nitride films. Appl. Phys. Lett., 103(25), 252602 (1 to 4).
Abstract: We report on the direct measurement of the electron-phonon relaxation time, τeph, in disordered TiN films. Measured values of τeph are from 5.5 ns to 88 ns in the 4.2 to 1.7 K temperature range and consistent with a T−3 temperature dependence. The electronic density of states at the Fermi level N0 is estimated from measured material parameters. The presented results confirm that thin TiN films are promising candidate-materials for ultrasensitive superconducting detectors.
The work was supported by the Ministry of Education and Science of the Russian Federation, Contract No. 14.B25.31.0007 and by the RFBR Grant No. 13-02-91159.
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Kovalyuk, V., Hartmann, W., Kahl, O., Kaurova, N., Korneev, A., Goltsman, G., et al. (2013). Absorption engineering of NbN nanowires deposited on silicon nitride nanophotonic circuits. Opt. Express, 21(19), 22683–22692.
Abstract: We investigate the absorption properties of U-shaped niobium nitride (NbN) nanowires atop nanophotonic circuits. Nanowires as narrow as 20nm are realized in direct contact with Si3N4 waveguides and their absorption properties are extracted through balanced measurements. We perform a full characterization of the absorption coefficient in dependence of length, width and separation of the fabricated nanowires, as well as for waveguides with different cross-section and etch depth. Our results show excellent agreement with finite-element analysis simulations for all considered parameters. The experimental data thus allows for optimizing absorption properties of emerging single-photon detectors co-integrated with telecom wavelength optical circuits.
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