| Records |
| Author |
Vasilev, D. D.; Malevannaya, E. I.; Moiseev, K. M.; Zolotov, P. I.; Antipov, A. V.; Vakhtomin, Y. B.; Smirnov, K. V. |
| Title |
Influence of deposited material energy on superconducting properties of the WSi films |
Type |
Conference Article |
| Year |
2020 |
Publication |
IOP Conf. Ser.: Mater. Sci. Eng. |
Abbreviated Journal |
IOP Conf. Ser.: Mater. Sci. Eng. |
| Volume |
781 |
Issue |
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Pages |
012013 (1 to 6) |
| Keywords |
WSi SSPD, SNSPD |
Abstract  |
WSi thin films have the advantages for creating SNSPDs with a large active area or array of detectors on a single substrate due to the amorphous structure. The superconducting properties of ultrathin WSi films substantially depends on their structure and thickness as the NbN films. Scientific groups investigating WSi films mainly focused only on changes of their thickness and the ratio of the components on the substrate at room temperature. This paper presents experiments to determine the effect of the bias potential on the substrate, the temperature of the substrate, and the peak power of pulsed magnetron sputtering, which is the equivalent of ionization, a tungsten target, on the surface resistance and superconducting properties of the WSi ultrathin films. The negative effect of the substrate temperature and the positive effect of the bias potential and the ionization coefficient (peak current) allow one to choose the best WSi films formation mode for SNSPD: substrate temperature 297 K, bias potential -60 V, and peak current 3.5 A. |
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1757-899X |
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no |
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1798 |
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| Author |
Baeva, E. M.; Titova, N. A.; Kardakova, A. I.; Piatrusha, S. U.; Khrapai, V. S. |
| Title |
Universal bottleneck for thermal relaxation in disordered metallic films |
Type |
Journal Article |
| Year |
2020 |
Publication |
JETP Lett. |
Abbreviated Journal |
Jetp Lett. |
| Volume |
111 |
Issue |
2 |
Pages |
104-108 |
| Keywords |
NbN disordered metallic films, thermal relaxation |
| Abstract |
We study the heat relaxation in current biased metallic films in the regime of strong electron–phonon coupling. A thermal gradient in the direction normal to the film is predicted, with a spatial temperature profile determined by the temperature-dependent heat conduction. In the case of strong phonon scattering, the heat conduction occurs predominantly via the electronic system and the profile is parabolic. This regime leads to the linear dependence of the noise temperature as a function of bias voltage, in spite of the fact that all the dimensions of the film are large compared to the electron–phonon relaxation length. This is in stark contrast to the conventional scenario of relaxation limited by the electron–phonon scattering rate. A preliminary experimental study of a 200-nm-thick NbN film indicates the relevance of our model for materials used in superconducting nanowire single-photon detectors. |
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0021-3640 |
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no |
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1164 |
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| Author |
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 |
Type |
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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Serial |
1266 |
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| Author |
Matyushkin, Y.; Kaurova, N.; Voronov, B.; Goltsman, G.; Fedorov, G. |
| Title |
On chip carbon nanotube tunneling spectroscopy |
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Journal Article |
| Year |
2020 |
Publication |
Fullerenes, Nanotubes and Carbon Nanostructures |
Abbreviated Journal |
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| Volume |
28 |
Issue |
1 |
Pages |
50-53 |
| Keywords |
carbon nanotubes, CNT, scanning tunneling microscope, STM |
| Abstract |
We report an experimental study of the band structure of individual carbon nanotubes (SCNTs) based on investigation of the tunneling density of states, i.e. tunneling spectroscopy. A common approach to this task is to use a scanning tunneling microscope (STM). However, this approach has a number of drawbacks, to overcome which, we propose another method – tunneling spectroscopy of SCNTs on a chip using a tunneling contact. This method is simpler, cheaper and technologically advanced than the STM. Fabrication of a tunnel contact can be easily integrated into any technological route, therefore, a tunnel contact can be used, for example, as an additional tool in characterizing any devices based on individual CNTs. In this paper we demonstrate a simple technological procedure that results in fabrication of good-quality tunneling contacts to carbon nanotubes. |
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Taylor & Francis |
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doi:10.1080/1536383X.2019.1671365 |
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1269 |
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| Author |
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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Manova, N. N.; Simonov, N. O.; Korneeva, Y. P.; Korneev, A. A. |
| Title |
Developing of NbN films for superconducting microstrip single-photon detector |
Type |
Conference Article |
| Year |
2020 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
| Volume |
1695 |
Issue |
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Pages |
012116 (1 to 5) |
| Keywords |
NbN SSPD, SNSPD, NbN films |
| 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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1742-6588 |
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no |
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1786 |
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| Author |
Elmanov, Ilia; Elmanova, Anna; Kovalyuk, Vadim; An, Pavel; Goltsman, Gregory |
| Title |
Integrated contra-directional coupler for NV-centers photon filtering |
Type |
Conference Article |
| Year |
2020 |
Publication |
Proc. 32-nd EMSS |
Abbreviated Journal |
Proc. 32-nd EMSS |
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Issue |
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Pages |
354-360 |
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NV-centers, nanodiamonds, quantum photonic integrated circuits, contra-direction coupler, Bragg gratings |
| Abstract |
We modelled an integrated optical contra-directional coupler on silicon nitride platform. Performance of the filter was studied depending on different parameters, including the grating period and the height of teeth of the Bragg grating near 637 nm operation wavelength. The obtained results can be used for a design and fabrication of quantum photonic integrated circuits with on-chip single-photon NV-centers in nanodiamonds. |
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2724-0029 |
ISBN |
978-88-85741-44-7 |
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32nd European Modeling & Simulation Symposium |
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no |
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1839 |
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| Author |
Zhang, X.; Lita, A. E.; Smirnov, K.; Liu, H. L.; Zhu, D.; Verma, V. B.; Nam, S. W.; Schilling, A. |
| Title |
Strong suppression of the resistivity near the superconducting transition in narrow microbridges in external magnetic fields |
Type |
Journal Article |
| Year |
2020 |
Publication |
Phys. Rev. B |
Abbreviated Journal |
Phys. Rev. B |
| Volume |
101 |
Issue |
6 |
Pages |
060508 (1 to 6) |
| Keywords |
MoSi, WSi films |
| Abstract |
We have investigated a series of superconducting bridges based on homogeneous amorphous WSi and MoSi films, with bridge widths w ranging from 2 to 1000μm and film thicknesses d∼4−6 and 100 nm. Upon decreasing the bridge widths below the respective Pearl lengths, we observe in all cases distinct changes in the characteristics of the resistive transitions to superconductivity. For each of the films, the resistivity curves R(B,T) separate at a well-defined and field-dependent temperature T∗(B) with decreasing the temperature, resulting in a dramatic suppression of the resistivity and a sharpening of the transitions with decreasing bridge width w. The associated excess conductivity in all the bridges scales as 1/w, which may suggest either the presence of a highly conducting region that is dominating the electric transport, or a change in the vortex dynamics in narrow enough bridges. We argue that this effect can only be observed in materials with sufficiently weak vortex pinning. |
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2469-9950 |
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no |
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1800 |
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Vodolazov, D. Y.; Manova, N. N.; Korneeva, Y. P.; Korneev, A. A. |
| Title |
Timing jitter in NbN superconducting microstrip single-photon detector |
Type |
Journal Article |
| Year |
2020 |
Publication |
Phys. Rev. Applied |
Abbreviated Journal |
Phys. Rev. Applied |
| Volume |
14 |
Issue |
4 |
Pages |
044041 (1 to 8) |
| Keywords |
NbN SSPD, SNSPD |
| 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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2331-7019 |
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no |
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1788 |
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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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1263 |
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