| Records |
| Author |
Sáysz, Wojciech; Guziewicz, Marek; Bar, Jan; Wegrzecki, Maciej; Grabiec, Piotr; Grodecki, Remigiusz; Wegrzecka, Iwona; Zwiller, Val; Milosnaya, Irina; Voronov, Boris; Gol’tsman, Gregory; Kitaygorsky, Jen; Sobolewski, Roman |
| Title |
Superconducting NbN nanostructures for single photon quantum detectors |
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Abstract |
| Year |
2008 |
Publication |
Proc. 7-th Int. Conf. Ion Implantation and Other Applications of Ions and Electrons |
Abbreviated Journal |
Proc. 7-th Int. Conf. Ion Implantation and Other Applications of Ions and Electrons |
| Volume |
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Pages |
160 |
| Keywords |
SSPD, SNSPD |
| Abstract |
Practical quantum systems such as quantum communication (QC) or quantum measurement systems require detectors with high speed, high sensitivity, high quantum efficiency (QE), and short deadtimes along with precise timing characteristics and low dark counts. Superconducting single photon detectors (SSPDs) based on ultrathin meander type NbN nanostripes (operated at T=2-5K) are a new and highly promising type of devices fulfilling above requirements. In this paper we present results of the SSPDs nanostructure technological optimization. The base for our detector is thin-film (4nm) NbN layer deposited on 350- P m-thick sapphire substrate The active element of the detector is a meander- nanostructure made of 4-nm-thick and 100-nm-wide NbN stripe, covering 10 u 10 P m 2 area with the filling factor ~0,5. The NbN superconducting films were deposited on sapphire substrates by DC reactive magnetron sputtering whereas the meander element of the detector was patterned by the direct electron-beam lithography followed by reactive-ion etching. To enhance the SSPD efficiency at Ȝ = 1.55 P m, we have performed an approach to increase the absorption of the detector by integrating it with optical resonant cavity. An optical microcavity optimized for absorption of 1.55 P m photons was designed as an one-mirror resonator consisting of a Ȝ/4 dielectric layer and a metallic mirror. The microcavity was deposited on the top of the NbN SSPD meander. The resonator was formed by the dielectric SiO 2 layer and metal mirror made of gold or palladium. Microcavity layers were deposited using a magnetron sputtering system. |
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1409 |
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Gershenzon, E. M.; Gol'tsman, G. N.; Zorin, M. A.; Karasik, B. S.; Trifonov, V. A. |
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Nonequilibrium and bolometric response of YBaCuO films in a resistive state to infrared low intensity radiation |
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Conference Article |
| Year |
1994 |
Publication |
Council on Low-temp. Phys. |
Abbreviated Journal |
Council on Low-temp. Phys. |
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Pages |
82-83 |
| Keywords |
YBCO HTS HEB |
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| Address |
Dubna |
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Russian |
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Joint Inst. for Nuclear Research, Dubna (Russian Federation); 296 p; 1994; p. 82-83; 30. Conference on low-temperature physics; 30. Soveshchanie po fizike nizkikh temperatur; Dubna (Russian Federation); 6-8 Sep 1994 |
| Notes |
Неравновесный и болометрический отклик YBaCuO пленок в резиотивном состоянии на инфракрасное лазерное излучение малой интенсивности |
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1632 |
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Beck, Matthias; Leiderer, Paul; Kabanov, Viktor V.; Gol'tsman, Gregory; Helm, Manfred; Demsar, Jure |
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Energy-gap dynamics of a superconductor NbN studied by time-resolved terahertz spectroscopy |
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Abstract |
| Year |
2012 |
Publication |
INIS |
Abbreviated Journal |
INIS |
| Volume |
45 |
Issue |
12 |
Pages |
1-3 |
| Keywords |
NbN energy gap |
| Abstract |
Using time-resolved terahertz (THz) spectroscopy we performed direct studies of the photoinduced suppression and recovery of the SC gap in a conventional SC NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the important microscopic constants: the Cooper pair-breaking rate via phonon absorption and the bare quasiparticle recombination rate. From the latter we were able to extract the dimensionless electron-phonon coupling constant, λ=1.1±0.1, in excellent agreement with theoretical estimates. The technique also allowed us to determine the absorbed energy required to suppress SC, which in NbN equals the thermodynamic condensation energy (in cuprates the two differ by an order of magnitude). Finally, we present the first studies of dynamics following resonant excitation with intense narrow band THz pulses tuned to above and below the superconducting gap. These suggest an additional process, particularly pronounced near Tc, that could be attributed to amplification of SC via effective quasiparticle cooling. |
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1383 |
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Lusche, Robert; Semenov, Alexey; Huebers, Heinz-Willhelm; Ilin, Konstantin; Siegel, Michael; Korneeva, Yuliya; Trifonov, Andrey; Korneev, Alexander; Goltsman, Gregory |
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Effect of the wire geometry and an externally applied magnetic field on the detection efficiency of superconducting nanowire single-photon detectors |
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Abstract |
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2013 |
Publication |
INIS |
Abbreviated Journal |
INIS |
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46 |
Issue |
8 |
Pages |
1-3 |
| Keywords |
TaN, NbN SSPD, SNSPD |
| Abstract |
The interest in single-photon detectors in the near-infrared wavelength regime for applications, e.g. in quantum cryptography has immensely increased in the last years. Superconducting nanowire single-photon detectors (SNSPD) already show quite reasonable detection efficiencies in the NIR which can even be further improved. Novel theoretical approaches including vortex-assisted photon counting state that the detection efficiency in the long wavelength region can be enhanced by the detector geometry and an applied magnetic field. We present spectral measurements in the wavelength range from 350-2500 nm of the detection efficiency of meander-type TaN and NbN SNSPD with varying nanowire line width from 80 to 250 nm. Due to the used experimental setup we can accurately normalize the measured spectra and are able to extract the intrinsic detection efficiency (IDE) of our detectors. The results clearly indicate an improvement of the IDE depending on the wire width according to the theoretic models. Furthermore we experimentally found that the smallest detectable photon-flux can be increased by applying a small magnetic field to the detectors. |
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1374 |
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Semenov, A. D.; Sergeev, A. V.; Kouminov, P.; Goghidze, I. G.; Heusinger, M. A.; Nebosis, R. S.; Gol'tsman, G. N.; Gershenzon, E. M.; Renk, K. F. |
| Title |
Transparency of YBCO film/substrate interfaces for thermal phonons determined by photoresponse measurements |
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Conference Article |
| Year |
1993 |
Publication |
Proc. 1st European Conf. on Appl. Supercond. |
Abbreviated Journal |
Proc. 1st European Conf. on Appl. Supercond. |
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2 |
Issue |
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Pages |
1443-1446 |
| Keywords |
YBCO HTS detectors |
| Abstract |
Direct measurements of the thermal boundary resistance were performed by means of the stationary method. In this approach the temperature of an electrically heated film is controlled by its dc resistance while an additional film on the same substrate is used as a thermometer monitoring substrate temperature. The temperature field in the substrate is then calculated to deduce the Kapitza temperature step at the interface between the heated strip and the substrate. The main statement of all afore-said papers is that experimental values of the thermal boundary resistance are too large to be explained by the acoustic mismatch model. In this paper we investigate transparency of YBaCuO film/substrate interfaces for thermal phonons by means of photoresponse measurements. We show that our data are in reasonable agreement with the acoustic mismatch theory. |
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Freyhardt, H. C. |
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3-88355-197-X |
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1st European conference on applied superconductivity |
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1661 |
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