Vasilev, D. D., Malevannaya, E. I., Moiseev, K. M., Zolotov, P. I., Antipov, A. V., Vakhtomin, Y. B., et al. (2020). Influence of deposited material energy on superconducting properties of the WSi films. In IOP Conf. Ser.: Mater. Sci. Eng. (Vol. 781, 012013 (1 to 6)).
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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Antipov, A. V., Seleznev, V. A., Vakhtomin, Y. B., Morozov, P. V., Vasilev, D. D., Malevannaya, E. I., et al. (2020). Investigation of WSi and NbN superconducting single-photon detectors in mid-IR range. In IOP Conf. Ser.: Mater. Sci. Eng. (Vol. 781, 012011 (1 to 5)).
Abstract: Spectral characteristics of WSi and NbN superconducting single-photon detectors with different surface resistance and width of nanowire strips have been investigated in the wavelength range of 1.3-2.5 μm. WSi structures with narrower strips demonstrated better performance for detection of single photons in longer wavelength range. The difference in normalized photon count rate for such structures reaches one order of magnitude higher in comparison with structures based on NbN thin films at 2.5 μm.
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Rath, P., Vetter, A., Kovalyuk, V., Ferrari, S., Kahl, O., Nebel, C., et al. (2016). Travelling-wave single-photon detectors integrated with diamond photonic circuits: operation at visible and telecom wavelengths with a timing jitter down to 23 ps. In J. - E. Broquin, & G. N. Conti (Eds.), Integrated Optics: Devices, Mat. Technol. XX (Vol. 9750, pp. 135–142). Spie.
Abstract: We report on the design, fabrication and measurement of travelling-wave superconducting nanowire single-photon detectors (SNSPDs) integrated with polycrystalline diamond photonic circuits. We analyze their performance both in the near-infrared wavelength regime around 1600 nm and at 765 nm. Near-IR detection is important for compatibility with the telecommunication infrastructure, while operation in the visible wavelength range is relevant for compatibility with the emission line of silicon vacancy centers in diamond which can be used as efficient single-photon sources. Our detectors feature high critical currents (up to 31 μA) and high performance in terms of efficiency (up to 74% at 765 nm), noise-equivalent power (down to 4.4×10-19 W/Hz1/2 at 765 nm) and timing jitter (down to 23 ps).
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Marsili, F., Bitauld, D., Fiore, A., Gaggero, A., Mattioli, F., Leoni, R., et al. (2010). Photon-number-resolution at telecom wavelength with superconducting nanowires. IntechOpen [DOI:10.5772/6920]. Retrieved August 25, 2024, from http://dx.doi.org/10.5772/6920.
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Lusche, R., Semenov, A., Huebers, H. - W., Ilin, K., Siegel, M., Korneeva, Y., et al. (2013). Effect of the wire geometry and an externally applied magnetic field on the detection efficiency of superconducting nanowire single-photon detectors. In INIS (Vol. 46, pp. 1–3).
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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Slysz, W., Wegrzecki, M., Papis, E., Gol'tsman, G. N., Verevkin, A., & Sobolewski, R. (2004). A method of optimization of the NbN superconducting single-photon detector (Vol. 36).
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Slysz, W., Wegrzecki, M., Bar, J., Grabiec, P., Gol'tsman, G. N., Verevkin, M., et al. (2004). NbN superconducting single-photon detectors coupled with a communication fiber (Vol. 37).
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Sobolewski, R., Xu, Y., Zheng, X., Williams, C., Zhang, J., Verevkin, A., et al. (2002). Spectral sensitivity of the NbN single-photon superconducting detector. IEICE Trans. Electron., E85-C(3), 797–802.
Abstract: We report our studies on the spectral sensitivity of superconducting NbN thin-film single-photon detectors (SPD's) capable of GHz counting rates of visible and near-infrared photons. In particular, it has been shown that a NbN SPD is sensitive to 1.55-µm wavelength radiation and can be used for quantum communication. Our SPD's exhibit experimentally measured intrinsic quantum efficiencies from 20% at 800 nm up to 1% at 1.55-µm wavelength. The devices demonstrate picosecond response time (<100 ps, limited by our readout system) and negligibly low dark counts. Spectral dependencies of photon counting of continuous-wave, 0.4-µm to 3.5-µm radiation, and 0.63-µm, 1.33-µm, and 1.55-µm laser-pulsed radiations are presented for the single-stripe-type and meander-type devices.
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Sobolewski, R., Verevkin, A., Gol'tsman, G. N., Lipatov, A., & Wilsher, K. (2003). Ultrafast superconducting single-photon optical detectors and their applications. IEEE Trans. Appl. Supercond., 13(2), 1151–1157.
Abstract: We present a new class of ultrafast single-photon detectors for counting both visible and infrared photons. The detection mechanism is based on photon-induced hotspot formation, which forces the supercurrent redistribution and leads to the appearance of a transient resistive barrier across an ultrathin, submicrometer-width, superconducting stripe. The devices were fabricated from 3.5-nm- and 10-nm-thick NbN films, patterned into <200-nm-wide stripes in the 4 /spl times/ 4-/spl mu/m/sup 2/ or 10 /spl times/ 10-/spl mu/m/sup 2/ meander-type geometry, and operated at 4.2 K, well below the NbN critical temperature (T/sub c/=10-11 K). Continuous-wave and pulsed-laser optical sources in the 400-nm-to 3500-nm-wavelength range were used to determine the detector performance in the photon-counting mode. Experimental quantum efficiency was found to exponentially depend on the photon wavelength, and for our best, 3.5-nm-thick, 100-/spl mu/m/sup 2/-area devices varied from >10% for 405-nm radiation to 3.5% for 1550-nm photons. The detector response time and jitter were /spl sim/100 ps and 35 ps, respectively, and were acquisition system limited. The dark counts were below 0.01 per second at optimal biasing. In terms of the counting rate, jitter, and dark counts, the NbN single-photon detectors significantly outperform their semiconductor counterparts. Already-identified applications for our devices range from noncontact testing of semiconductor CMOS VLSI circuits to free-space quantum cryptography and communications.
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Gol'tsman, G., Minaeva, O., Korneev, A., Tarkhov, M., Rubtsova, I., Divochiy, A., et al. (2007). Middle-infrared to visible-light ultrafast superconducting single-photon detectors. IEEE Trans. Appl. Supercond., 17(2), 246–251.
Abstract: We present an overview of the state-of-the-art of NbN superconducting single-photon detectors (SSPDs). Our devices exhibit quantum efficiency (QE) of up to 30% in near-infrared wavelength and 0.4% at 5 mum, with a dark-count rate that can be as low as 10 -4 s -1 . The SSPD structures integrated with lambda/4 microcavities achieve a QE of 60% at telecommunication, 1550-nm wavelength. We have also developed a new generation of SSPDs that possess the QE of large-active-area devices, but, simultaneously, are characterized by low kinetic inductance that allows achieving short response times and the GHz-counting rate with picosecond timing jitter. The improvements presented in the SSPD development, such as fiber-coupled SSPDs, make our detectors most attractive for high-speed quantum communications and quantum computing.
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Yang, J. K. W., Kerman, A. J., Dauler, E. A., Anant, V., Rosfjord, K. M., & Berggren, K. K. (2007). Modeling the electrical and thermal response of superconducting nanowire single-photon detectors. IEEE Trans. Appl. Supercond., 17(2), 581–585.
Abstract: We modeled the response of superconducting nanowire single-photon detectors during a photodetection event, taking into consideration only the thermal and electrical properties of a superconducting NbN nanowire on a sapphire substrate. Our calculations suggest that heating which occurs after the formation of a photo-induced resistive barrier is responsible for the generation of a measurable voltage pulse. We compared this numerical result with experimental data of a voltage pulse from a slow device, i.e. large kinetic inductance, and obtained a good fit. Using this electro-thermal model, we estimated the temperature rise and the resistance buildup in the nanowire, and the return current at which the nanowire becomes superconducting again. We also show that the reset time of these photodetectors can be decreased by the addition of a series resistance and provide supporting experimental data. Finally we present preliminary results on a detector latching behavior that can also be explained using the electro-thermal model.
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Korneeva, Y., Florya, I., Semenov, A., Korneev, A., & Goltsman, G. (2011). New generation of nanowire NbN superconducting single-photon detector for mid-infrared. IEEE Trans. Appl. Supercond., 21(3), 323–326.
Abstract: We present a break-through approach to mid-infrared single-photon detection based on nanowire NbN superconducting single-photon detectors (SSPD). Although SSPD became a mature technology for telecom wavelengths (1.3-1.55 μm) its further expansion to mid-infrared wavelength was hampered by low sensitivity above 2 μm. We managed to overcome this limit by reducing the nanowire width to 50 nm, while retaining high superconducting properties and connecting the wires in parallel to produce a voltage response of sufficient magnitude. The new device exhibits 10 times better quantum efficiency at 3.5 μm wavelength than the “standard” SSPD.
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Schuck, C., Pernice, W. H. P., Minaeva, O., Li, M., Gol'tsman, G., Sergienko, A. V., et al. (2013). Matrix of integrated superconducting single-photon detectors with high timing resolution. IEEE Trans. Appl. Supercond., 23(3), 2201007.
Abstract: We demonstrate a large grid of individually addressable superconducting single photon detectors on a single chip. Each detector element is fully integrated into an independent waveguide circuit with custom functionality at telecom wavelengths. High device density is achieved by fabricating the nanowire detectors in traveling wave geometry directly on top of silicon-on-insulator waveguides. Our superconducting single photon detector matrix includes detector designs optimized for high detection efficiency, low dark count rate, and high timing accuracy. As an example, we exploit the high timing resolution of a particularly short nanowire design to resolve individual photon round-trips in a cavity ring-down measurement of a silicon ring resonator.
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Gol’tsman, G., Okunev, O., Chulkova, G., Lipatov, A., Dzardanov, A., Smirnov, K., et al. (2001). Fabrication and properties of an ultrafast NbN hot-electron single-photon detector. IEEE Trans. Appl. Supercond., 11(1), 574–577.
Abstract: A new type of ultra-high-speed single-photon counter for visible and near-infrared wavebands based on an ultrathin NbN hot-electron photodetector (HEP) has been developed. The detector consists of a very narrow superconducting stripe, biased close to its critical current. An incoming photon absorbed by the stripe produces a resistive hotspot and causes an increase in the film’s supercurrent density above the critical value, leading to temporary formation of a resistive barrier across the device and an easily measurable voltage pulse. Our NbN HEP is an ultrafast (estimated response time is 30 ps; registered time, due to apparatus limitations, is 150 ps), frequency unselective device with very large intrinsic gain and negligible dark counts. We have observed sequences of output pulses, interpreted as single-photon events for very weak laser beams with wavelengths ranging from 0.5 /spl mu/m to 2.1 /spl mu/m and the signal-to-noise ratio of about 30 dB.
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Korneev, A. A., Korneeva, Y. P., Mikhailov, M. Y., Pershin, Y. P., Semenov, A. V., Vodolazov, D. Y., et al. (2015). Characterization of MoSi superconducting single-photon detectors in the magnetic field. IEEE Trans. Appl. Supercond., 25(3), 2200504 (1 to 4).
Abstract: We investigate the response mechanism of nanowire superconducting single-photon detectors (SSPDs) made of amorphous MoxSi1-x. We study the dependence of photon count and dark count rates on bias current in magnetic fields up to 113 mT at 1.7 K temperature. The observed behavior of photon counts is similar to the one recently observed in NbN SSPDs. Our results show that the detecting mechanism of relatively high-energy photons does not involve the vortex penetration from the edges of the film, and on the contrary, the detecting mechanism of low-energy photons probably involves the vortex penetration from the film edges.
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