Murphy, A., Semenov, A., Korneev, A., Korneeva, Y., Gol'tsman, G., & Bezryadin, A. (2015). Three temperature regimes in superconducting photon detectors: quantum, thermal and multiple phase-slips as generators of dark counts. Sci. Rep., 5, 10174 (1 to 10).
Abstract: We perform measurements of the switching current distributions of three w approximately 120 nm wide, 4 nm thick NbN superconducting strips which are used for single-photon detectors. These strips are much wider than the diameter of the vortex cores, so they are classified as quasi-two-dimensional (quasi-2D). We discover evidence of macroscopic quantum tunneling by observing the saturation of the standard deviation of the switching distributions at temperatures around 2 K. We analyze our results using the Kurkijarvi-Garg model and find that the escape temperature also saturates at low temperatures, confirming that at sufficiently low temperatures, macroscopic quantum tunneling is possible in quasi-2D strips and can contribute to dark counts observed in single photon detectors. At the highest temperatures the system enters a multiple phase-slip regime. In this range single phase-slips are unable to produce dark counts and the fluctuations in the switching current are reduced.
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Kahl, O., Ferrari, S., Kovalyuk, V., Goltsman, G. N., Korneev, A., & Pernice, W. H. P. (2015). Waveguide integrated superconducting single-photon detectors with high internal quantum efficiency at telecom wavelengths. Sci. Rep., 5, 10941 (1 to 11).
Abstract: Superconducting nanowire single-photon detectors (SNSPDs) provide high efficiency for detecting individual photons while keeping dark counts and timing jitter minimal. Besides superior detection performance over a broad optical bandwidth, compatibility with an integrated optical platform is a crucial requirement for applications in emerging quantum photonic technologies. Here we present efficiencies close to unity at 1550nm wavelength. This allows for the SNSPDs to be operated at bias currents far below the critical current where unwanted dark count events reach milli-Hz levels while on-chip detection efficiencies above 70% are maintained. The measured dark count rates correspond to noiseequivalent powers in the 10–19W/Hz–1/2 range and the timing jitter is as low as 35ps. Our detectors are fully scalable and interface directly with waveguide-based optical platforms.
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Manova, N. N., Simonov, N. O., Korneeva, Y. P., & Korneev, A. A. (2020). Developing of NbN films for superconducting microstrip single-photon detector. In J. Phys.: Conf. Ser. (Vol. 1695, 012116 (1 to 5)).
Abstract: We optimized NbN films on a Si substrate with a buffer SiO2 layer to produce superconducting microstrip single-photon detectors with saturated dependence of quantum efficiency (QE) versus normalized bias current. We varied thickness of films and observed the maximum QE saturation for device based on the thinner film with the lowest ratio RS300/RS20.
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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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Polyakova, M. I., Korneev, A. A., & Semenov, A. V. (2020). Comparison single- and double- spot detection efficiencies of SSPD based to MoSi and NbN films. In J. Phys.: Conf. Ser. (Vol. 1695, 012146 (1 to 3)).
Abstract: In this work, we present results of quantum detector tomography of superconducting single photon detector (SSPD) based on MoSi film, and compare them with previously reported data on NbN. We find that for both materials hot spot interaction length coincides with the strip width, and the dependence of single and double-spot detection efficiencies on bias current are compatible with sufficiently large hot-spot size, approaching the strip width.
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Manova, N. N., Smirnov, E. O., Korneeva, Y. P., Korneev, A. A., & Goltsman, G. N. (2019). Superconducting photon counter for nanophotonics applications. In J. Phys.: Conf. Ser. (Vol. 1410, 012147 (1 to 5)).
Abstract: We develop large area superconducting single-photon detector SSPD with a micron-wide strip suitable for free-space coupling or packaging with multi-mode optical fibres. The detector sensitive area is 20 μm in diameter. In near infrared (1330 nm wavelength) our SSPD exhibits above 30% detection efficiency with low dark counts and 45 ps timing jitter.
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Polyakova, M. I., Florya, I. N., Semenov, A. V., Korneev, A. A., & Goltsman, G. N. (2019). Extracting hot-spot correlation length from SNSPD tomography data. In J. Phys.: Conf. Ser. (Vol. 1410, 012166 (1 to 4)).
Abstract: We present data of quantum detector tomography for the samples specifically optimized for this problem. Using this method, we take results of hot-spot correlation length of 17 ± 2 nm.
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Zubkova, E., Golikov, A., An, P., Kovalyuk, V., Korneev, A., Ferrari, S., et al. (2019). CWDM demultiplexer using anti-reflection, contra-directional couplers based on silicon nitride rib waveguide. In J. Phys.: Conf. Ser. (Vol. 1410, 012179).
Abstract: We report on the development and fabrication of a 9-channel coarse wavelength-division multiplexing for telecommunication wavelengths (1550 nm) using anti-reflection contra-directional couplers, based on silicon nitride (Si3N4) rib waveguide. The transmitted and reflected spectrum in each channel of the demultiplexer were measured. The average full width at half maximum of the transmitted (reflected) spectra is about 3 nm.
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Komrakova, S., Javadzade, J., Vorobyov, V., Bolshedvorskii, S., Soshenko, V., Akimov, A., et al. (2019). CMOS compatible nanoantenna-nanodiamond integration. In J. Phys.: Conf. Ser. (Vol. 1410, 012180).
Abstract: Here we demonstrate CMOS compatible method to deterministically produce nanoantenna with nanodiamonds systems on example of bull-eye antenna on top of on hyperbolic metamaterials. We study the statistics of the placement of nanodiamonds and measure the fluorescence lifetime and the second-order correlation function of NV-centers inside nanodiamonds.
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Dryazgov, M., Semenov, A., Manova, N., Korneeva, Y., & Korneev, A. (2020). Modelling of normal domain evolution after single-photon absorption of a superconducting strip of micron width. In J. Phys.: Conf. Ser. (Vol. 1695, 012195 (1 to 4)).
Abstract: The present paper describes a modelling of normal domain evolution in superconducting strip of micron width using solving differential equations describing the temperature and current changes. The solving results are compared with experimental data. This comparison demonstrates the high accuracy of the model. In future, it is possible to employ this model for improvement of single photon detector based on micron-scale superconducting strips.
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Korneev, A., Divochiy, A., Tarkhov, M., Minaeva, O., Seleznev, V., Kaurova, N., et al. (2008). New advanced generation of superconducting NbN-nanowire single-photon detectors capable of photon number resolving. In J. Phys.: Conf. Ser. (Vol. 97, 012307 (1 to 6)).
Abstract: We present our latest generation of ultrafast superconducting NbN single-photon detectors (SSPD) capable of photon-number resolving (PNR). We have developed, fabricated and tested a multi-sectional design of NbN nanowire structures. The novel SSPD structures consist of several meander sections connected in parallel, each having a resistor connected in series. The novel SSPDs combine 10 μm × 10 μm active areas with a low kinetic inductance and PNR capability. That resulted in a significantly reduced photoresponse pulse duration, allowing for GHz counting rates. The detector's response magnitude is directly proportional to the number of incident photons, which makes this feature easy to use. We present experimental data on the performances of the PNR SSPDs. The PNR SSPDs are perfectly suited for fibreless free-space telecommunications, as well as for ultrafast quantum cryptography and quantum computing.
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Baeva, E., Sidorova, M., Korneev, A., & Goltsman, G. (2018). Precise measurement of the thermal conductivity of superconductor. In Proc. AIP Conf. (Vol. 1936, 020003 (1 to 4)).
Abstract: Measuring the thermal properties such as the heat capacity provide information about intrinsic mechanisms operated inside. In general, the ratio between electron and phonon specific heat Ce/Cp shows how the absorbed energy shared between electron and phonon subsystems. In this work we make estimations for amplitude-modulated absorption of THz radiation technique for investigation of the ratio Ce/Cp in superconducting Niobium Nitride (NbN) at T = Tc. Our results indicates that experimentally the frequency of modulation has to be extra large to extract the quantity. We perform a new technique allowed to work at low frequency with accurately measurement of absorbed power.
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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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Korneeva, Y. P., Manova, N. N., Florya, I. N., Mikhailov, M. Y., Dobrovolskiy, O. V., Korneev, A. A., et al. (2020). Different single-photon response of wide and narrow superconducting MoxSi1−x strips. Phys. Rev. Applied, 13(2), 024011 (1 to 7).
Abstract: The photon count rate (PCR) of superconducting single-photon detectors made of MoxSi1−x films shaped as a 2-μm-wide strip and a 115-nm-wide meander strip line is studied experimentally as a function of the dc biasing current at different values of the perpendicular magnetic field. For the wide strip, a crossover current Icross is observed, below which the PCR increases with an increasing magnetic field and above which it decreases. This behavior contrasts with the narrow MoxSi1−x meander, for which no crossover current is observed, thus suggesting different photon-detection mechanisms in the wide and narrow strips. Namely, we argue that in the wide strip the absorbed photon destroys superconductivity locally via the vortex-antivortex mechanism for the emergence of resistance, while in the narrow meander superconductivity is destroyed across the whole strip line, forming a hot belt. Accordingly, the different photon-detection mechanisms associated with vortices and the hot belt determine the qualitative difference in the dependence of the PCR on the magnetic field.
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Shcherbatenko, M., Lobanov, Y., Semenov, A., Kovalyuk, V., Korneev, A., Ozhegov, R., et al. (2016). Potential of a superconducting photon counter for heterodyne detection at the telecommunication wavelength. Opt. Express, 24(26), 30474–30484.
Abstract: Here, we report on the successful operation of a NbN thin film superconducting nanowire single-photon detector (SNSPD) in a coherent mode (as a mixer) at the telecommunication wavelength of 1550 nm. Providing the local oscillator power of the order of a few picowatts, we were practically able to reach the quantum noise limited sensitivity. The intermediate frequency gain bandwidth (also referred to as response or conversion bandwidth) was limited by the spectral band of a single-photon response pulse of the detector, which is proportional to the detector size. We observed a gain bandwidth of 65 MHz and 140 MHz for 7 x 7 microm2 and 3 x 3 microm2 devices, respectively. A tiny amount of the required local oscillator power and wide gain and noise bandwidths, along with unnecessary low noise amplification, make this technology prominent for various applications, with the possibility for future development of a photon counting heterodyne-born large-scale array.
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