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| Author |
Lobanov, Y. V.; Vakhtomin, Y. B.; Pentin, I. V.; Rosental, V. A.; Smirnov, K. V.; Goltsman, G. N.; Volkov, O. Y.; Dyuzhikov, I. N.; Galiev, R. R.; Ponomarev, D. S.; Khabibullin, R. A. |
| Title |
Time-resolved measurements of light–current characteristic and mode competition in pulsed THz quantum cascade laser |
Type |
Journal Article |
| Year |
2021 |
Publication |
Optical Engineering |
Abbreviated Journal |
Optical Engineering |
| Volume |
60 |
Issue |
8 |
Pages |
1-8 |
| Keywords |
HEB, terahertz pulse generation, terahertz pulse detection, QCL, quantum cascade laser, superconducting hot electron bolometer |
| Abstract |
Quantum cascade lasers (QCL) are widely adopted as prominent and easy-to-use solid-state sources of terahertz radiation. Yet some applications require generation and detection of very sharp and narrow terahertz-range pulses with a specific spectral composition. We have studied time-resolved light-current (L–I) characteristics of multimode THz QCL operated with a fast ramp of the injection current. Detection of THz pulses was carried out using an NbN superconducting hot-electron bolometer with the time constant of the order of 1 ns while the laser bias current was swept during a single driving pulse. A nonmonotonic behavior of the L–I characteristic with several visually separated subpeaks was found. This behavior is associated with the mode competition in THz QCL cavity, which we confirm by L–I measurements with use of an external Fabry–Perot interferometer for a discrete mode selection. We also have demonstrated the possibility to control the L–I shape with suppression of one of the subpeaks by simply adjusting the off-axis parabolic mirror for optimal optical alignment for one of the laser modes. The developed technique paves the way for rapid characterization of pulsed THz QCLs for further studies of the possibilities of using this approach in remote sensing. |
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10.1117/1.Oe.60.8.082019 |
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1260 |
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| Author |
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 |
Type |
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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1262 |
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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 |
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 |
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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no |
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Serial |
1267 |
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| Author |
Shcherbatenko, M. L.; Elezov, M. S.; Goltsman, G. N.; Sych, D. V. |
| Title |
Sub-shot-noise-limited fiber-optic quantum receiver |
Type |
Journal Article |
| Year |
2020 |
Publication |
Phys. Rev. A |
Abbreviated Journal |
Phys. Rev. A |
| Volume |
101 |
Issue |
3 |
Pages |
032306 (1 to 5) |
| Keywords |
SSPD mixer, SNSPD |
| 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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2469-9926 |
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no |
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1268 |
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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 |
Serial |
1269 |
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| Author |
Rasulova, G. K.; Pentin, I. V.; Goltsman, G. N. |
| Title |
Terahertz emission from a weakly-coupled GaAs/AlGaAs superlattice biased into three different modes of current self-oscillations |
Type |
Journal Article |
| Year |
2019 |
Publication |
AIP Advances |
Abbreviated Journal |
AIP Advances |
| Volume |
9 |
Issue |
10 |
Pages |
105220 |
| Keywords |
GaAs/AlGaAs superlattice, SL, NbN HEB |
| Abstract |
Radio-frequency modulated terahertz (THz) emission power from weakly-coupled GaAs/AlGaAs superlattice (SL) has been increased by parallel connection of several SL mesas. Each SL mesa is a self-oscillator with its own oscillation frequency and mode. In coupled non-identical SL mesas biased at different voltages within the hysteresis loop the chaotic, quasiperiodic and frequency-locked modes of self-oscillations of current arise. THz emission was detected when three connected in parallel SL mesas were biased into the frequency-locked and quasiperiodic modes of self-oscillations of current, while in the chaotic mode of those it falls to the noise level. |
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Edition |
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| ISSN |
2158-3226 |
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no |
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Serial |
1274 |
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| Author |
Elezov, M.; Ozhegov, R.; Goltsman, G.; Makarov, V. |
| Title |
Countermeasure against bright-light attack on superconducting nanowire single-photon detector in quantum key distribution |
Type |
Journal Article |
| Year |
2019 |
Publication |
Opt. Express |
Abbreviated Journal |
Opt. Express |
| Volume |
27 |
Issue |
21 |
Pages |
30979-30988 |
| Keywords |
SSPD, SNSPD |
| Abstract |
We present an active anti-latching system for superconducting nanowire single-photon detectors. We experimentally test it against a bright-light attack, previously used to compromise security of quantum key distribution. Although our system detects continuous blinding, the detector is shown to be partially blindable and controllable by specially tailored sequences of bright pulses. Improvements to the countermeasure are suggested. |
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English |
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1094-4087 |
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| Notes |
PMID:31684339 |
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no |
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1275 |
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Antipov, S.; Trifonov, A.; Krause, S.; Meledin, D.; Kaurova, N.; Rudzinski, M.; Desmaris, V.; Belitsky, V.; Goltsman, G. |
| Title |
Improved bandwidth of a 2 THz hot-electron bolometer heterodyne mixer fabricated on sapphire with a GaN buffer layer |
Type |
Journal Article |
| Year |
2019 |
Publication |
Supercond. Sci. Technol. |
Abbreviated Journal |
Supercond. Sci. Technol. |
| Volume |
32 |
Issue |
7 |
Pages |
075003 |
| Keywords |
NbN HEB mixer, GaN buffer layer, sapphire substrate |
| Abstract |
We report on the signal-to-noise and gain bandwidth of a niobium nitride (NbN) hot-electron bolometer (HEB) mixer at 2 THz fabricated on a sapphire substrate with a GaN buffer layer. Two mixers with different DC properties and geometrical dimensions were studied and they demonstrated very close bandwidth performance. The signal-to-noise bandwidth is increased to 8 GHz in comparison to the previous results, obtained without a buffer-layer. The data were taken in a quasi-optical system with the use of the signal-to-noise method, which is close to the signal levels used in actual astrophysical observations. We find an increase of the gain bandwidth to 5 GHz. The results indicate that prior results obtained on a substrate of crystalline GaN can also be obtained on a conventional sapphire substrate with a few micron MOCVD-deposited GaN buffer-layer. |
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IOP Publishing |
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Antipov_2019 |
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1277 |
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Nikogosyan, A. S.; Martirosyan, R. M.; Hakhoumian, A. A.; Makaryan, A. H.; Tadevosyan, V. R.; Goltsman, G. N.; Antipov, S. V. |
| Title |
Effect of absorption on the efficiency of terahertz radiation generation in the metal waveguide partially filled with nonlinear crystal LiNbO3, DAST or ZnTe |
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Journal Article |
| Year |
2019 |
Publication |
J. Contemp. Phys. |
Abbreviated Journal |
J. Contemp. Phys. |
| Volume |
54 |
Issue |
1 |
Pages |
97-104 |
| Keywords |
nonlinear crystal, THz, waveguide |
| Abstract |
The influence of terahertz (THz) radiation absorption on the efficiency of generation of coherent THz radiation in the system ‘nonlinear-optical crystal partially filling the cross section of a rectangular metal waveguide’ has been investigated. The efficiency of the nonlinear frequency conversion of optical laser radiation to the THz range depends on the loss in the system and the fulfillment of the phase-matching (FM) condition in a nonlinear crystal. The method of partially filling of a metal waveguide with a nonlinear optical crystal is used to ensure phase matching. The phase matching is achieved by numerical determination of the thickness of the nonlinear crystal, that is the degree of partial filling of the waveguide. The attenuation of THz radiation caused by losses both in the metal walls of the waveguide and in the crystal was studied, taking into account the dimension of the cross section of the waveguide, the degree of partial filling, and the dielectric constant of the crystal. It is shown that the partial filling of the waveguide with a nonlinear crystal results in an increase in the efficiency of generation of THz radiation by an order of magnitude, owing to the decrease in absorption. |
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Edition |
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1068-3372 |
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no |
| Call Number |
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Serial |
1289 |
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| Author |
Nikoghosyan, A. S.; Martirosyan, R. M.; Hakhoumian, A. A.; Makaryan, A. H.; Tadevosyan, V. R.; Goltsman, G. N.; Antipov, S. V. |
| Title |
Effect of absorption on the efficiency of THz radiation generation in a nonlinear crystal placed into a waveguide |
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Journal Article |
| Year |
2018 |
Publication |
Armenian J. Phys. |
Abbreviated Journal |
Armenian J. Phys. |
| Volume |
11 |
Issue |
4 |
Pages |
257-262 |
| Keywords |
THz, waveguide, nonlinear crystal |
| Abstract |
The effect of THz radiation absorption on the efficiency of generation of coherent THz radiation in a nonlinear optical crystal placed into a metal rectangular waveguide is studied. The efficiency of the nonlinear conversion of optical laser radiation to the THz band is also a function of the phase-matching (PM) condition inside the nonlinear crystal. The method of partial filling of a metal waveguide with a nonlinear optical crystal is used to ensure phase matching. Phase matching was obtained by the proper choice of the thickness of the nonlinear crystal, namely the degree of partial filling of the waveguide. We have studied the THz radiation attenuation caused by the losses in both the metal walls of the waveguide and in the crystal, taking into account the dimension of the cross section of the waveguide, the degree of partial filling and its dielectric constant. |
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Edition |
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| ISSN |
1829-1171 |
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no |
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Serial |
1291 |
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| Author |
Ren, Y.; Zhang, D. X.; Zhou, K. M.; Miao, W.; Zhang, W.; Shi, S. C.; Seleznev, V.; Pentin, I.; Vakhtomin, Y.; Smirnov, K. |
| Title |
10.6 μm heterodyne receiver based on a superconducting hot-electron bolometer mixer and a quantum cascade laser |
Type |
Journal Article |
| Year |
2019 |
Publication |
AIP Advances |
Abbreviated Journal |
AIP Advances |
| Volume |
9 |
Issue |
7 |
Pages |
075307 |
| Keywords |
NbN HEB mixers, QCL, IR |
| Abstract |
We report on the development of a heterodyne receiver at mid-infrared wavelength for high-resolution spectroscopy applications. The receiver employs a superconducting NbN hot electron bolometer as a mixer and a room temperature distributed feedback quantum cascade laser operating at 10.6 μm (28.2 THz) as a local oscillator. The stabilization of the heterodyne receiver has been achieved using a feedback loop controlling the output power of the laser. Improved Allan variance times as well as a double sideband receiver noise temperature of 5000 K and a noise bandwidth of 2.8 GHz of the receiver system are demonstrated.
The work is supported in part by the National Key R&D Program of China under Grant 2018YFA0404701, by the CAS program under Grant QYZDJ-SSW-SLH043 and GJJSTD20180003, by the National Natural Science Foundation of China (NSFC) under Grant 11773083, by the “Hundred Talents Program” of the “Pioneer Initiative”, and in part by the CAS Key Lab for Radio Astronomy. |
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2158-3226 |
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no |
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1293 |
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| Author |
Finkel, M.; Thierschmann, H.; Galatro, L.; Katan, A. J.; Thoen, D. J.; de Visser, P. J.; Spirito, M.; Klapwijk, T. M. |
| Title |
Performance of THz components based on microstrip PECVD SiNx technology |
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Journal Article |
| Year |
2017 |
Publication |
IEEE Trans. THz Sci. Technol. |
Abbreviated Journal |
IEEE Trans. THz Sci. Technol. |
| Volume |
7 |
Issue |
6 |
Pages |
765-771 |
| Keywords |
transmission line measurements, power transmission lines, dielectrics, couplers, submillimeter wave circuits, coplanar waveguides, micromechanical devices |
| Abstract |
We present a performance analysis of passive THz components based on Microstrip transmission lines with a 2-μmthin plasma-enhanced chemical vapor deposition grown silicon nitride (PECVD SiNX) dielectric layer. A set of thru-reflect-line calibration structures is used for basic transmission line characterizations. We obtain losses of 9 dB/mm at 300 GHz. Branchline hybrid couplers are realized that exhibit 2.5-dB insertion loss, 1-dB amplitude imbalance, and -26-dB isolation, in agreement with simulations. We use the measured center frequency to determine the dielectric constant of the PECVD SiN x , which yields 5.9. We estimate the wafer-to-wafer variations to be of the order of 1%. Directional couplers are presented which exhibit -12-dB transmission to the coupled port and -26 dB to the isolated port. For transmission lines with 5-μm-thin silicon nitride (SiN x ), we observe losses below 4 dB/mm. The thin SiN x dielectric membrane makes the THz components compatible with scanning probe microscopy cantilevers allowing the application of this technology in on-chip circuits of a THz near-field microscope. |
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2156-342X |
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no |
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1294 |
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| Author |
Kardakova, A. I.; Coumou, P. C. J. J.; Finkel, M. I.; Morozov, D. V.; An, P. P.; Goltsman, G. N.; Klapwijk, T. M. |
| Title |
Electron–phonon energy relaxation time in thin strongly disordered titanium nitride films |
Type |
Journal Article |
| Year |
2015 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
| Volume |
25 |
Issue |
3 |
Pages |
1-4 |
| Keywords |
TiN MKID |
| Abstract |
We have measured the energy relaxation times from the electron bath to the phonon bath in strongly disordered TiN films grown by atomic layer deposition. The measured values of τ eph vary from 12 to 91 ns. Over a temperature range from 3.4 to 1.7 K, they follow T -3 temperature dependence, which are consistent with values of τ eph reported previously for sputtered TiN films. For the most disordered film, with an effective elastic mean free path of 0.35 nm, we find a faster relaxation and a stronger temperature dependence, which may be an additional indication of the influence of strong disorder on a superconductor. |
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1051-8223 |
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1296 |
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| Author |
Korneeva, Y. P.; Vodolazov, D. Y.; Semenov, A. V.; Florya, I. N.; Simonov, N.; Baeva, E.; Korneev, A. A.; Goltsman, G. N.; Klapwijk, T. M. |
| Title |
Optical single-photon detection in micrometer-scale NbN bridges |
Type |
Journal Article |
| Year |
2018 |
Publication |
Phys. Rev. Applied |
Abbreviated Journal |
Phys. Rev. Applied |
| Volume |
9 |
Issue |
6 |
Pages |
064037 (1 to 13) |
| Keywords |
NbN SSPD, SNSPD |
| Abstract |
We demonstrate experimentally that single-photon detection can be achieved in micrometer-wide NbN bridges, with widths ranging from 0.53 to 5.15 μm and for photon wavelengths of 408 to 1550 nm. The microbridges are biased with a dc current close to the experimental critical current, which is estimated to be about 50% of the theoretically expected depairing current. These results offer an alternative to the standard superconducting single-photon detectors, based on nanometer-scale nanowires implemented in a long meandering structure. The results are consistent with improved theoretical modeling based on the theory of nonequilibrium superconductivity, including the vortex-assisted mechanism of initial dissipation. |
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2331-7019 |
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1303 |
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