| Records |
| Author |
Prokhodtsov, A.; Kovalyuk, V.; An, P.; Golikov, A.; Shakhovoy, R.; Sharoglazova, V.; Udaltsov, A.; Kurochkin, Y.; Goltsman, G. |
| Title |
Silicon nitride Mach-Zehnder interferometer for on-chip quantum random number generation |
Type |
Conference Article |
| Year |
2020 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
| Volume |
1695 |
Issue |
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Pages |
012118 |
| Keywords |
Mach-Zehnder interferometer, MZI |
| 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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| ISSN |
1742-6588 |
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no |
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1178 |
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| Author |
Venediktov, I. O.; Elezov, M. S.; Prokhodtsov, A. I.; Kovalyuk, V. V.; An, P. P.; Golikov, A. D.; Shcherbatenko, M. L.; Sych, D. V.; Goltsman, G. N. |
| Title |
Study of microheater’s phase modulation for on-chip Kennedy receiver |
Type |
Conference Article |
| Year |
2020 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
| Volume |
1695 |
Issue |
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Pages |
012117 |
| Keywords |
Mach-Zehnder interferometers, MZI |
| Abstract |
In this work we describe phase modulators for several Mach-Zehnder interferometers (MZI) on silicon nitride platform for telecomm wavelength (1550 nm). We obtained current-voltage and phase-voltage curves for these modulators. MZI are needed for experimental realisation of various quantum receivers that can distinguish weak coherent states of light with extremely low error. Thermo-optical (TO) modulation is ensured by microheaters on one of the arms of MZI, which enables the change of the refractive index of the material with temperature. This approach allows to apply the necessary voltage to the golden microheaters to obtain the required phase change. For the on-chip microheaters we demonstrate the dependence of the phase shift on the voltage applied to our on-chip microheaters. |
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| ISSN |
1742-6588 |
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no |
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1179 |
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| Author |
Elmanov, I.; Sardi, F.; Xia, K.; Kornher, T.; Kovalyuk, V.; Prokhodtsov, A.; An, P.; Kuzin, A.; Elmanova, A.; Goltsman, G.; Kolesov, R. |
| Title |
Development of focusing grating couplers for lithium niobate on insulator platform |
Type |
Conference Article |
| Year |
2020 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
| Volume |
1695 |
Issue |
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Pages |
012127 |
| Keywords |
grating couplers, lithium niobat |
| 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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| ISSN |
1742-6588 |
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no |
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1180 |
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Zvagelsky, R. D.; Chubich, D. A.; Kolymagin, D. A.; Korostylev, E. V.; Kovalyuk, V. V.; Prokhodtsov, A. I.; Tarasov, A. V.; Goltsman, G. N.; Vitukhnovsky, A. G. |
| Title |
Three-dimensional polymer wire bonds on a chip: morphology and functionality |
Type |
Journal Article |
| Year |
2020 |
Publication |
J. Phys. D: Appl. Phys. |
Abbreviated Journal |
J. Phys. D: Appl. Phys. |
| Volume |
53 |
Issue |
35 |
Pages |
355102 |
| Keywords |
photonic wire bonds, PWB |
| Abstract |
Modern microchip-scale transceivers are capable of transmitting data at rates of the order of several terabits per second. In this regard, there is an urgent need to improve the interfaces connecting the chips and extend the bandpass of the interconnections. We use an approach combining silicon nitride nanophotonic circuits with 3D polymer waveguides fabricated by direct laser writing, which can be used as photonic interconnections or photonic wire bonds (PWB). These structures are designed, simulated, fabricated, and optimized for better light transmission at the telecommunication wavelength. An important part of this work is the study of the telecom signal transmission in a 3D polymer waveguide connecting two silicon nitride facing tapers. Two cases are considered: the tapers are one opposite the other or misaligned. Initially, the PWB shape was chosen to be Gaussian and then optimized: the top was circle-shaped and with the lower part still being Gaussian. Transmission losses were measured for both types of waveguides with different shapes. The idea of an optical multi-level crossing for photonic integrated circuits is also suggested as a solution to the problem of interconnections within a single chip. |
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0022-3727 |
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no |
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1181 |
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Rasulova, G. K.; Pentin, I. V.; Vakhtomin, Y. B.; Smirnov, K. V.; Khabibullin, R. A.; Klimov, E. A.; Klochkov, A. N.; Goltsman, G. N. |
| Title |
Pulsed terahertz radiation from a double-barrier resonant tunneling diode biased into self-oscillation regime |
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Journal Article |
| Year |
2020 |
Publication |
J. Appl. Phys. |
Abbreviated Journal |
J. Appl. Phys. |
| Volume |
128 |
Issue |
22 |
Pages |
224303 (1 to 11) |
| Keywords |
HEB, resonant tunneling diode, RTD |
| Abstract |
The study of the bolometer response to terahertz (THz) radiation from a double-barrier resonant tunneling diode (RTD) biased into the negative differential conductivity region of the I–V characteristic revealed that the RTD emits two pulses in a period of intrinsic self-oscillations of current. The bolometer pulse repetition rate is a multiple of the fundamental frequency of the intrinsic self-oscillations of current. The bolometer pulses are detected at two critical points with a distance between them being half or one-third of a period of the current self-oscillations. An analysis of the current self-oscillations and the bolometer response has shown that the THz photon emission is excited when the tunneling electrons are trapped in (the first pulse) and then released from (the second pulse) miniband states. |
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0021-8979 |
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no |
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1262 |
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Simonov, N. O.; Korneeva, Y. P.; Korneev, A. A.; Goltsman, G. N. |
| Title |
Enhance of the superconducting properties of the NbN/Au bilayer bridges |
Type |
Conference Article |
| Year |
2020 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
| Volume |
1695 |
Issue |
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Pages |
012132 (1 to 4) |
| Keywords |
SSPD, SNSPD |
| 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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1742-6588 |
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no |
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1263 |
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Elezov, M. S.; Shcherbatenko, M. L.; Sych, D. V.; Goltsman, G. N. |
| Title |
Development of control method for an optimal quantum receiver |
Type |
Conference Article |
| Year |
2020 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
| Volume |
1695 |
Issue |
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Pages |
012126 |
| Keywords |
Helstrom bound, SPD, single photon detector, below quantum limit |
| 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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1742-6588 |
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no |
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1264 |
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Shcherbatenko, M.; Elezov, M.; Sych, D.; Goltsman, G. N. |
| Title |
Optimal fiber optic scheme for sub-SQL quantum receiver realization |
Type |
Conference Article |
| Year |
2020 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
| Volume |
1695 |
Issue |
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Pages |
012140 |
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sub-SQL, below quantum limit, QL, system quantum limit, SQL |
| 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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1742-6588 |
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no |
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1265 |
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Sidorova, M.; Semenov, Alexej D.; Hübers, H.-W.; Ilin, K.; Siegel, M.; Charaev, I.; Moshkova, M.; Kaurova, N.; Goltsman, G. N.; Zhang, X.; Schilling, A. |
| Title |
Electron energy relaxation in disordered superconducting NbN films |
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Journal Article |
| Year |
2020 |
Publication |
Phys. Rev. B |
Abbreviated Journal |
Phys. Rev. B |
| Volume |
102 |
Issue |
5 |
Pages |
054501 (1 to 15) |
| Keywords |
NbN SSPD, SNSPD, HEB, bandwidth, relaxation time |
| Abstract |
We report on the inelastic-scattering rate of electrons on phonons and relaxation of electron energy studied by means of magnetoconductance, and photoresponse, respectively, in a series of strongly disordered superconducting NbN films. The studied films with thicknesses in the range from 3 to 33 nm are characterized by different Ioffe-Regel parameters but an almost constant product qTl (qT is the wave vector of thermal phonons and l is the elastic mean free path of electrons). In the temperature range 14–30 K, the electron-phonon scattering rates obey temperature dependencies close to the power law 1/τe−ph∼Tn with the exponents n≈3.2–3.8. We found that in this temperature range τe−ph and n of studied films vary weakly with the thickness and square resistance. At 10 K electron-phonon scattering times are in the range 11.9–17.5 ps. The data extracted from magnetoconductance measurements were used to describe the experimental photoresponse with the two-temperature model. For thick films, the photoresponse is reasonably well described without fitting parameters, however, for thinner films, the fit requires a smaller heat capacity of phonons. We attribute this finding to the reduced density of phonon states in thin films at low temperatures. We also show that the estimated Debye temperature in the studied NbN films is noticeably smaller than in bulk material. |
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2469-9950 |
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no |
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1266 |
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Ovchinnikov, O. V.; Perepelitsa, A. S.; Smirnov, M. S.; Latyshev, A. N.; Grevtseva, I. G.; Vasiliev, R. B.; Goltsman, G. N.; Vitukhnovsky, A. G. |
| Title |
Luminescence of colloidal Ag2S/ZnS core/shell quantum dots capped with thioglycolic acid |
Type |
Journal Article |
| Year |
2020 |
Publication |
J. Luminescence |
Abbreviated Journal |
J. Luminescence |
| Volume |
220 |
Issue |
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Pages |
117008 (1 to 7) |
| Keywords |
Ag2S QD, quantum dots |
| Abstract |
The features of IR luminescence of colloidal AgS QDs passivated with thioglycolic acid (AgS/TGA) under the formation of AgS/ZnS/TGA core/shell QDs are considered. A 4.5-fold increase in the quantum yield of recombination IR luminescence within the band with a peak at 960 nm (1.29 eV), full width at half maximum of 250 nm (0.34 eV), and the Stokes shift with respect to the exciton absorption of 0.6 eV was found. The increase in the IR luminescence intensity of AgS/ZnS/TGA QDs is accompanied by an increase in the average luminescence lifetime from 2.9 ns to 14.3 ns, which is explained as “healing” of surface trap states during the formation of the ZnS shell. For the first time, the enhancement of the luminescence intensity photodegradation (hereinafter referred to as fatigue) was found during the formation of the AgS/ZnS/TGA core/shell QDs. The luminescence fatigue is irreversible. We conclude that the initial stage of photolysis of the AgS core QDs under laser irradiation plays a key role. Low-atomic photolytic clusters of silver formed on the AgS core QDs act as luminescence quenching centers and do not reveal structural transformations into AgS, provided that the clusters are not in contact with TGA. |
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0022-2313 |
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1267 |
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