| Records |
| 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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| ISSN |
2469-9950 |
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no |
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1800 |
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| Author |
Ptitsina, N. G.; Chulkova, G. M.; Il’in, K. S.; Sergeev, A. V.; Pochinkov, F. S.; Gershenzon, E. M.; Gershenson, M. E. |
| Title |
Electron-phonon interaction in disordered metal films: The resistivity and electron dephasing rate |
Type |
Journal Article |
| Year |
1997 |
Publication |
Phys. Rev. B |
Abbreviated Journal |
Phys. Rev. B |
| Volume |
56 |
Issue |
16 |
Pages |
10089-10096 |
| Keywords |
disordered metal films, electron-phonon interaction, electron dephasing rate, resistivity |
| Abstract |
The temperature dependence of the resistance of films of Al, Be, and NbC with small values of the electron mean free path l=1.5–10nm has been measured at 4.2–300 K. The resistance of all the films contains a T2 contribution that is proportional to the residual resistance; this contribution has been attributed to the interference between the elastic electron scattering and the electron-phonon scattering. Fitting the data to the theory of the electron-phonon-impurity interference (M. Yu. Reiser and A. V. Sergeev, Zh. Eksp. Teor. Fiz. 92, 224 (1987) [Sov. Phys. JETP 65, 1291 (1987)]), we obtain constants of interaction of the electrons with transverse phonons, and estimate the contribution of this interaction to the electron dephasing rate in thin films of Au, Al, Be, Nb, and NbC. Our estimates are in a good agreement with the experimental data on the inelastic electron-phonon scattering in these films. This indicates that the interaction of electrons with transverse phonons controls the electron-phonon relaxation rate in thin-metal films over a broad temperature range. |
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| ISSN |
0163-1829 |
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no |
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Serial |
1766 |
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| Author |
Sergeev, A.; Mitin, V. |
| Title |
Electron-phonon interaction in disordered conductors: Static and vibrating scattering potentials |
Type |
Journal Article |
| Year |
2000 |
Publication |
Phys. Rev. B. |
Abbreviated Journal |
Phys. Rev. B. |
| Volume |
61 |
Issue |
9 |
Pages |
6041-6047 |
| Keywords |
disordered conductors, scattering potential, electron-phonon interaction |
| Abstract |
Employing the Keldysh diagram technique, we calculate the electron-phonon energy relaxation rate in a conductor with the vibrating and static δ-correlated random electron-scattering potentials. If the scattering potential is completely dragged by phonons, this model yields the Schmid’s result for the inelastic electron-scattering rate τ−1e−ph. At low temperatures the effective interaction decreases due to disorder, and τ−1e−ph∝T4l (l is the electron mean-free path). In the presense of the static potential, quantum interference of numerous scattering processes drastically changes the effective electron-phonon interaction. In particular, at low temperatures the interaction increases, and τ−1e−ph∝T2/l. Along with an enhancement of the interaction, which is observed in disordered metallic films and semiconducting structures at low temperatures, the suggested model allows us to explain the strong sensitivity of the electron relaxation rate to the microscopic quality of a particular film. |
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0163-1829 |
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no |
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307 |
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| Author |
Sidorova, M.; Semenov, A.; Hübers, H.-W.; Kuzmin, A.; Doerner, S.; Ilin, K.; Siegel, M.; Charaev, I.; Vodolazov, D. |
| Title |
Timing jitter in photon detection by straight superconducting nanowires: Effect of magnetic field and photon flux |
Type |
Journal Article |
| Year |
2018 |
Publication |
Phys. Rev. B |
Abbreviated Journal |
Phys. Rev. B |
| Volume |
98 |
Issue |
13 |
Pages |
134504 (1 to 14) |
| Keywords |
SNSPD, NbN namowires |
| Abstract |
We studied the effects of the external magnetic field and photon flux on timing jitter in photon detection by straight superconducting NbN nanowires. At two wavelengths 800 and 1560 nm, statistical distribution in the appearance times of photon counts exhibits Gaussian shape at small times and an exponential tail at large times. The characteristic exponential time is larger for photons with smaller energy and increases with external magnetic field while variations in the Gaussian part of the distribution are less pronounced. Increasing photon flux drives the nanowire from the discrete quantum detection regime to the uniform bolometric regime that averages out fluctuations of the total number of nonequilibrium electrons created by the photon and drastically reduces jitter. The difference between standard deviations of Gaussian parts of distributions for these two regimes provides the measure for the strength of electron-number fluctuations; it increases with the photon energy. We show that the two-dimensional hot-spot detection model explains qualitatively the effect of magnetic field. |
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2469-9950 |
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no |
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1842 |
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| Author |
Cao, Aiqin; Jiang, L.; Chen, S.H.; Antipov, S.V.; Shi, S.C. |
| Title |
IF gain bandwidth of a quasi-optical NbN superconducting HEB mixer |
Type |
Conference Article |
| Year |
2007 |
Publication |
Proc. International conference on microwave and millimeter wave technology |
Abbreviated Journal |
Proc. ICMMT |
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Issue |
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Pages |
1-3 |
| Keywords |
HEB, mixer, gain bandwidth |
| Abstract |
In this paper, the intermediate frequency (IF) gain bandwidth of a quasi-optical NbN superconducting hot-electron bolometer (HEB) mixer is investigated at 500 GHz with an IF system incorporating with a frequency down-converting scheme which is able to sweep the IF signal in a frequency range of 0.3-4 GHz. The IF gain bandwidth of the device is measured to be 1.5 GHz when it is biased at a voltage of the minimum noise temperature, and becomes larger when the bias voltage increases. |
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Builin |
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RPLAB @ lobanovyury @ |
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575 |
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| Author |
Tong, C.-Y.E.; Meledin, D.V.; Marrone, D.P.; Paine, S.N.; Gibson, H.; Blundell, R. |
| Title |
Near field vector beam measurements at 1 THz |
Type |
Journal Article |
| Year |
2003 |
Publication |
IEEE Microw. Compon. Lett. |
Abbreviated Journal |
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| Volume |
13 |
Issue |
6 |
Pages |
235-237 |
| Keywords |
HEB, mixer, waveguide, LO power, local oscillator power, saturation effect, dynamic range |
| Abstract |
We have performed near-field vector beam measurements at 1.03 THz to characterize and align the receiver optics of a superconducting receiver. The signal source is a harmonic generator mounted on an X-Y translation stage. We model the measured two-dimensional complex beam pattern by a fundamental Gaussian mode, from which we derive the position of the beam center, the beam radius and the direction of propagation. By performing scans in the planes separated by 400 mm, we have confirmed that our beam pattern measurements are highly reliable. |
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1531-1309 |
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no |
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RPLAB @ lobanovyury @ |
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574 |
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Kuznetsov, K. A.; Kornienko, V. V.; Vakhtomin, Y. B.; Pentin, I. V.; Smirnov, K. V.; Kitaeva, G. K. |
| Title |
Generation and detection of optical-terahertz biphotons via spontaneous parametric downconversion |
Type |
Conference Article |
| Year |
2018 |
Publication |
Proc. ICLO |
Abbreviated Journal |
Proc. ICLO |
| Volume |
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Issue |
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Pages |
303 |
| Keywords |
NbN HEB applications |
| Abstract |
We study spontaneous parametric downconversion (SPDC) in the strongly non-degenerate regime when the idler wave hits the terahertz range. By using the hot-electron bolometer, for the first time the SPDC-generated idler-wave photons were directly detected in the terahertz frequency range. Spectrum of corresponding signal photons was measured using standard technique by the CCD camera. Possible applications of correlated optical-terahertz biphotons are discussed. |
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International Conference Laser Optics |
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no |
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Serial |
1806 |
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Smirnov, K.; Moshkova, M.; Antipov, A.; Morozov, P.; Vakhtomin, Y. |
| Title |
The cascade switching of the photon number resolving superconducting single-photon detectors |
Type |
Journal Article |
| Year |
2021 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
| Volume |
31 |
Issue |
2 |
Pages |
1-4 |
| Keywords |
PNR SSPD, SNSPD |
| Abstract |
In this article, present the first detailed study of cascade switching in superconducting photon number resolving detectors. The detectors were made in the form of four parallel nanowires, coupled with the single-mode optical fiber and mounted into a closed-cycle refrigerator with a temperature of 2.1 K. We found out the value of additional false pulses (N cas.sw. ) appearing due to cascade switching and showed that it is possible to set up the detector bias current that corresponds to a high level of the detection efficiency and a low level of N cas.sw. simultaneously. We reached the detection efficiency of 60% and N cas.sw. = 0.3%. |
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Edition |
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| ISSN |
1051-8223 |
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no |
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1796 |
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| Author |
Klapwijk, T. M.; Semenov, A. V. |
| Title |
Engineering physics of superconducting hot-electron bolometer mixers |
Type |
Journal Article |
| Year |
2017 |
Publication |
IEEE Trans. THz Sci. Technol. |
Abbreviated Journal |
IEEE Trans. THz Sci. Technol. |
| Volume |
7 |
Issue |
6 |
Pages |
627-648 |
| Keywords |
HEB mixers |
| Abstract |
Superconducting hot-electron bolometers are presently the best performing mixing devices for the frequency range beyond 1.2 THz, where good-quality superconductor-insulator-superconductor devices do not exist. Their physical appearance is very simple: an antenna consisting of a normal metal, sometimes a normal-metal-superconductor bilayer, connected to a thin film of a narrow short superconductor with a high resistivity in the normal state. The device is brought into an optimal operating regime by applying a dc current and a certain amount of local-oscillator power. Despite this technological simplicity, its operation has found to be controlled by many different aspects of superconductivity, all occurring simultaneously. A core ingredient is the understanding that there are two sources of resistance in a superconductor: a charge-conversion resistance occurring at a normal-metal-superconductor interface and a resistance due to time-dependent changes of the superconducting phase. The latter is responsible for the actual mixing process in a nonuniform superconducting environment set up by the bias conditions and the geometry. The present understanding indicates that further improvement needs to be found in the use of other materials with a faster energy relaxation rate. Meanwhile, several empirical parameters have become physically meaningful indicators of the devices, which will facilitate the technological developments. |
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2156-342X |
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no |
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1292 |
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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 |
Type |
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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1294 |
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