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Dryazgov M, Semenov A, Manova N, Korneeva Y, Korneev A. Modelling of normal domain evolution after single-photon absorption of a superconducting strip of micron width. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 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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Elezov MS, Shcherbatenko ML, Sych DV, Goltsman GN. Development of control method for an optimal quantum receiver. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 012126.
Abstract: We propose a method for optimal displacement controlling of an optimal quantum receiver for registrations a binary coherent signal. An optimal receiver is able to distinguish between two phase-modulated states of a coherent signal. The optimal receiver controlling method can be used later in practice in various physical implementations of the optimal receiver.
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Elmanov I, Sardi F, Xia K, Kornher T, Kovalyuk V, Prokhodtsov A, et al. Development of focusing grating couplers for lithium niobate on insulator platform. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 012127.
Abstract: In this paper, we fabricate and experimentally study focusing grating couplers for lithium niobate on an insulator photonic platform. The transmittance of a waveguide equipped with in- and out-couplers with respect to the grating period is measured with and without silicon dioxide cladding applied. Our results show the influence of silicon dioxide cladding on the efficiency and the central wavelength of grating couplers and can be used to improve grating coupling efficiency. Our study is supported by numerical simulations.
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Elmanova A, An P, Kovalyuk V, Golikov A, Elmanov I, Goltsman G. Study of silicon nitride O-ring resonator for gas-sensing applications. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 012124.
Abstract: In this work, we experimentally studied the influence of different gaseous surroundings on silicon nitride O-ring resonator transmission. We compared the obtained results with numerical calculations and theoretical analysis and found a good agreement between them. Our results have a great potential for gas sensing applications, where a compact footprint and high efficiency are desired simultaneously.
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Komrakova S, Kovalyuk V, An P, Golikov A, Rybin M, Obraztsova E, et al. Effective absorption coefficient of a graphene atop of silicon nitride nanophotonic circuit. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 012135.
Abstract: In this paper, we demonstrate the results of a study of the optical absorption properties of graphene integrated with silicon nitride O-ring resonator. We fabricated an array of O-ring resonators with different graphene coverage area atop. By measuring the transmission spectra of nanophotonic devices with and without graphene, we calculated the effective absorption coefficient of the graphene on a rib silicon nitride waveguide.
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Manova NN, Simonov NO, Korneeva YP, Korneev AA. Developing of NbN films for superconducting microstrip single-photon detector. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 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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Polyakova MI, Korneev AA, Semenov AV. Comparison single- and double- spot detection efficiencies of SSPD based to MoSi and NbN films. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 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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Prokhodtsov A, Kovalyuk V, An P, Golikov A, Shakhovoy R, Sharoglazova V, et al. Silicon nitride Mach-Zehnder interferometer for on-chip quantum random number generation. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 012118.
Abstract: In this work, we experimentally studied silicon nitride Mach-Zehnder interferometer (MZI) with two directional couplers and 400 ps optical delay line for telecom wavelength 1550 nm. We achieved the extinction ratio in a range of 0.76-13.86 dB and system coupling losses of 28-44 dB, depending on the parameters of directional couplers. The developed interferometer is promising for the use in a compact random number generator for the needs of a fully integrated quantum cryptography system, where compact design, as well as high generation speed, are needed.
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Shcherbatenko M, Elezov M, Sych D, Goltsman GN. Optimal fiber optic scheme for sub-SQL quantum receiver realization. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 012140.
Abstract: Practical implementation of high-precision quantum measurements is an important problem in modern science. One of the main parts of the quantum receiver is the optical scheme. We developed and tested several optical circuits based on different types of interferometers, namely Sagnac-based scheme, Mach-Zehnder-based scheme, and Michelson-based scheme. All these schemes are assembled with optical fibers and fiber-optic components, since the fiber-optic implementation is closest to application in practical devices. Schemes were evaluated according to two main criteria: extinction and interference stability. On the basis of the obtained data, it can be concluded that the most suitable is the scheme based on the Mach-Zehnder interferometer. In continuous mode, we were able to obtain an interference extinction about 30 dB with acceptable temporal stability.
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Shurakov A, Mikhailov D, Belikov I, Kaurova N, Zilberley T, Prikhodko A, et al. Planar Schottky diode with a Γ-shaped anode suspended bridge. In: J. Phys.: Conf. Ser. Vol 1695.; 2020. 012154.
Abstract: In this paper we report on the fabrication of a planar Schottky diode utilizing a Г-shaped anode suspended bridge. The bridge maintains transition between the top and bottom level planes of a 1.4 µm thick GaAs mesa. To implement the profile of a suspended bridge and inward tilt of a mesa wall adjacent to it, we make use of an anisotropic etching of gallium arsenide. The geometry proposed enables the fabrication of a diode with mesa of an arbitrary thickness to mitigate AC losses in the diode layered structure at terahertz frequencies of interest. For frequencies beyond 1 THz, it is also beneficial to use the geometry for the implementation of n-GaAs/n-InGaAs heterojunction Schottky diodes grown on InP substrate.
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