Sidorova, M. V., Kozorezov, A. G., Semenov, A. V., Korneeva, Y. P., Mikhailov, M. Y., Devizenko, A. Y., et al. (2018). Nonbolometric bottleneck in electron-phonon relaxation in ultrathin WSi films. Phys. Rev. B, 97(18), 184512 (1 to 13).
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 τe−ph∼140–190 ps at TC=3.4K, supporting the results of earlier measurements by independent techniques.
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Sidorova, M. V., Kozorezov, A. G., Semenov, A. V., Korneev, A. A., Chulkova, G. M., Korneeva, Y. P., et al. (2018). Non-bolometric bottleneck in electron-phonon relaxation in ultra-thin WSi film. arXiv:1607.07321v4 [physics.ins-det].
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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Minaeva, O., Fraine, A., Korneev, A., Divochiy, A., Goltsman, G., & Sergienko, A. (2012). High resolution optical time-domain reflectometry using superconducting single-photon detectors. In Frontiers in Opt. 2012/Laser Sci. XXVIII (Fw3a.39). Optical Society of America.
Abstract: We discuss the advantages and limitations of single-photon optical time-domain reflectometry with superconducting single-photon detectors. The higher two-point resolution can be achieved due to superior timing performance of SSPDs in comparison with InGaAs APDs.
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Ozhegov, R., Elezov, M., Kurochkin, Y., Kurochkin, V., Divochiy, A., Kovalyuk, V., et al. (2014). Quantum key distribution over 300. In A. A. Orlikovsky (Ed.), Proc. SPIE (Vol. 9440, 1F (1 to 9)). SPIE.
Abstract: We discuss the possibility of polarization state reconstruction and measurement over 302 km by Superconducting Single- Photon Detectors (SSPDs). Because of the excellent characteristics and the possibility to be effectively coupled to singlemode optical fiber many applications of the SSPD have already been reported. The most impressive one is the quantum key distribution (QKD) over 250 km distance. This demonstration shows further possibilities for the improvement of the characteristics of quantum-cryptographic systems such as increasing the bit rate and the quantum channel length, and decreasing the quantum bit error rate (QBER). This improvement is possible because SSPDs have the best characteristics in comparison with other single-photon detectors. We have demonstrated the possibility of polarization state reconstruction and measurement over 302.5 km with superconducting single-photon detectors. The advantage of an autocompensating optical scheme, also known as “plugandplay” for quantum key distribution, is high stability in the presence of distortions along the line. To increase the distance of quantum key distribution with this optical scheme we implement the superconducting single photon detectors (SSPD). At the 5 MHz pulse repetition frequency and the average photon number equal to 0.4 we measured a 33 bit/s quantum key generation for a 101.7 km single mode ber quantum channel. The extremely low SSPD dark count rate allowed us to keep QBER at 1.6% level.
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Shcherbatenko, M. L., Elezov, M. S., Goltsman, G. N., & Sych, D. V. (2020). Sub-shot-noise-limited fiber-optic quantum receiver. Phys. Rev. A, 101(3), 032306 (1 to 5).
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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Gol’tsman, G. N., Okunev, O., Chulkova, G., Lipatov, A., Semenov, A., Smirnov, K., et al. (2001). Picosecond superconducting single-photon optical detector. Appl. Phys. Lett., 79(6), 705–707.
Abstract: We experimentally demonstrate a supercurrent-assisted, hotspot-formation mechanism for ultrafast detection and counting of visible and infrared photons. A photon-induced hotspot leads to a temporary formation of a resistive barrier across the superconducting sensor strip and results in an easily measurable voltage pulse. Subsequent hotspot healing in ∼30 ps time frame, restores the superconductivity (zero-voltage state), and the detector is ready to register another photon. Our device consists of an ultrathin, very narrow NbN strip, maintained at 4.2 K and current-biased close to the critical current. It exhibits an experimentally measured quantum efficiency of ∼20% for 0.81 μm wavelength photons and negligible dark counts.
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Simonov, N. O., Korneeva, Y. P., Korneev, A. A., & Goltsman, G. N. (2020). Enhance of the superconducting properties of the NbN/Au bilayer bridges. In J. Phys.: Conf. Ser. (Vol. 1695, 012132 (1 to 4)).
Abstract: We experimentally demonstrate strong temperature dependence of the critical current of the superconducting 600-nm-wide and 5-μm-long bridge made of NbN/Au bilayer. The result is achieved due to the proximity effect realized between the highly disordered superconducting NbN layer and low resistive normal-metal Au layer.
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Vodolazov, D. Y., Manova, N. N., Korneeva, Y. P., & Korneev, A. A. (2020). Timing jitter in NbN superconducting microstrip single-photon detector. Phys. Rev. Applied, 14(4), 044041 (1 to 8).
Abstract: We experimentally study timing jitter of single-photon detection by NbN superconducting strips with width w ranging from 190 nm to 3μm. We find that timing jitter of both narrow (190 nm) and micron-wide strips is about 40 ps at currents where internal detection efficiency η saturates and it is close to our instrumental jitter. We also calculate intrinsic timing jitter in wide strips using the modified time-dependent Ginzburg-Landau equation coupled with a two-temperature model. We find that with increasing width the intrinsic timing jitter increases and the effect is most considerable at currents where a rapid growth of η changes to saturation. We relate it with complicated vortex and antivortex dynamics, which depends on a photon’s absorption site across the strip and its width. The model also predicts that at current close to depairing current the intrinsic timing jitter of a wide strip could be about ℏ/kBTc (Tc is a critical temperature of superconductor), i.e., the same as for a narrow strip.
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Rosfjord, K. M., Yang, J. K. W., Dauler, E. A., Anant, V., Berggren, K. K., Kerman, A. J., et al. (2006). Increased detection efficiencies of nanowire single-photon detectors by integration of an optical cavity and anti-reflection coating. In CLEO/QELS (JTuF2 (1 to 2)).
Abstract: We fabricate and test superconducting NbN-nanowire single-photon detectors with an integrated optical cavity and anti-reflection coating. We design the cavity and coating such as to maximize absorption in the NbN film of the detector.
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Korneeva, Y. P., Mikhailov, M. Y., Pershin, Y. P., Manova, N. N., Divochiy, A. V., Vakhtomin, Y. B., et al. (2014). Superconducting single-photon detector made of MoSi film. Supercond. Sci. Technol., 27(9), 095012.
Abstract: We fabricated and characterized nanowire superconducting single-photon detectors made of 4 nm thick amorphous Mox Si1−x films. At 1.7 K the best devices exhibit a detection efficiency (DE) up to 18% at 1.2 $\mu {\rm m}$ wavelength of unpolarized light, a characteristic response time of about 6 ns and timing jitter of 120 ps. The DE was studied in wavelength range from 650 nm to 2500 nm. At wavelengths below 1200 nm these detectors reach their maximum DE limited by photon absorption in the thin MoSi film.
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