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Słysz W, Wegrzecki M, Bar J, Grabiec P, Górska M, Zwiller V, et al. Fibre-coupled, single photon detector based on NbN superconducting nanostructures for quantum communications. J Modern Opt. 2007;54(2-3):315–26.
Abstract: We present a novel, two-channel, single photon receiver based on two fibre-coupled, NbN, superconducting, single photon detectors (SSPDs). The SSPDs are nanostructured superconducting meanders and are known for ultrafast and efficient detection of visible-to-infrared photons. Coupling between the NbN detector and optical fibre was achieved using a micromechanical photoresist ring placed directly over the SSPD, holding the fibre in place. With this arrangement, we obtained coupling efficiencies up to ∼30%. Our experimental results showed that the best receiver had a near-infrared system quantum efficiency of 0.33% at 4.2 K. The quantum efficiency increased exponentially with the photon energy increase, reaching a few percent level for visible-light photons. The photoresponse pulses of our devices were limited by the meander high kinetic inductance and had the rise and fall times of approximately 250 ps and 5 ns, respectively. The receiver's timing jitter was in the 37 to 58 ps range, approximately 2 to 3 times larger than in our older free-space-coupled SSPDs. We stipulate that this timing jitter is in part due to optical fibre properties. Besides quantum communications, the two-detector arrangement should also find applications in quantum correlation experiments.
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Kahl O, Ferrari S, Kovalyuk V, Vetter A, Lewes-Malandrakis G, Nebel C, et al. Spectrally multiplexed single-photon detection with hybrid superconducting nanophotonic circuits: supplementary material. Osa; 2017.
Abstract: This document provides supplementary information to “Spectrally multiplexed single-photon detection with hybrid superconducting nanophotonic circuits", DOI:10.1364/optica.4.000557. Here we detail the on-chip spectrometer design, its characterization and the experimental setup we used. In addition, we present a detailed report concerning the characterization of the superconducting nanowire single photon detectors. In the final sections, we describe sample preparation and characterization of the nanodiamonds containing silicon vacancy color centers.
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Marsili F, Bitauld D, Divochiy A, Gaggero A, Leoni R, Mattioli F, et al. Superconducting nanowire photon number resolving detector at telecom wavelength. In: CLEO/QELS. Optical Society of America; 2008. Qmj1 (1 to 2).
Abstract: We demonstrate a photon-number-resolving (PNR) detector, based on parallel superconducting nanowires, capable of resolving up to 5 photons in the telecommunication wavelength range, with sensitivity and speed far exceeding existing approaches.
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Minaeva O, Fraine A, Korneev A, Divochiy A, Goltsman G, Sergienko A. High resolution optical time-domain reflectometry using superconducting single-photon detectors. In: Frontiers in Opt. 2012/Laser Sci. XXVIII. Optical Society of America; 2012. Fw3a.39.
Abstract: We discuss the advantages and limitations of single-photon optical time-domain reflectometry with superconducting single-photon detectors. The higher two-point resolution can be achieved due to superior timing performance of SSPDs in comparison with InGaAs APDs.
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Verevkin A, Slysz W, Pearlman A, Zhang J, Sobolewski R, Okunev O, et al. Real-time GHz-rate counting of infrared photons using nanostructured NbN superconducting detectors. In: CLEO/QELS. Optical Society of America; 2003. CThM8.
Abstract: We demonstrate that our ultrathin, nanometer-width NbN superconducting single-photon detectors are capable of above 1-GHz-frequency, real-time counting of near-infrared photons. The measured system jitter of the detector is below 15 ps.
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Zhang J, Pearlman A, Slysz W, Verevkin A, Sobolewski R, Okunev O, et al. Infrared picosecond superconducting single-photon detectors for CMOS circuit testing. In: CLEO/QELS. Optical Society of America; 2003. Cmv4.
Abstract: Novel, NbN superconducting single-photon detectors have been developed for ultrafast, high quantum efficiency detection of single quanta of infrared radiation. Our devices have been successfully implemented in a commercial VLSI CMOS circuit testing system.
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Shcherbatenko M, Lobanov Y, Semenov A, Kovalyuk V, Korneev A, Ozhegov R, et al. Potential of a superconducting photon counter for heterodyne detection at the telecommunication wavelength. Opt Express. 2016;24(26):30474–84.
Abstract: Here, we report on the successful operation of a NbN thin film superconducting nanowire single-photon detector (SNSPD) in a coherent mode (as a mixer) at the telecommunication wavelength of 1550 nm. Providing the local oscillator power of the order of a few picowatts, we were practically able to reach the quantum noise limited sensitivity. The intermediate frequency gain bandwidth (also referred to as response or conversion bandwidth) was limited by the spectral band of a single-photon response pulse of the detector, which is proportional to the detector size. We observed a gain bandwidth of 65 MHz and 140 MHz for 7 x 7 microm2 and 3 x 3 microm2 devices, respectively. A tiny amount of the required local oscillator power and wide gain and noise bandwidths, along with unnecessary low noise amplification, make this technology prominent for various applications, with the possibility for future development of a photon counting heterodyne-born large-scale array.
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Arutyunov KY, Ramos-Alvarez A, Semenov AV, Korneeva YP, An PP, Korneev AA, et al. Superconductivity in highly disordered NbN nanowires. Nanotechnol. 2016;27(47):47lt02 (1 to 8).
Abstract: The topic of superconductivity in strongly disordered materials has attracted significant attention. These materials appear to be rather promising for fabrication of various nanoscale devices such as bolometers and transition edge sensors of electromagnetic radiation. The vividly debated subject of intrinsic spatial inhomogeneity responsible for the non-Bardeen-Cooper-Schrieffer relation between the superconducting gap and the pairing potential is crucial both for understanding the fundamental issues of superconductivity in highly disordered superconductors, and for the operation of corresponding nanoelectronic devices. Here we report an experimental study of the electron transport properties of narrow NbN nanowires with effective cross sections of the order of the debated inhomogeneity scales. The temperature dependence of the critical current follows the textbook Ginzburg-Landau prediction for the quasi-one-dimensional superconducting channel I c approximately (1-T/T c)(3/2). We find that conventional models based on the the phase slip mechanism provide reasonable fits for the shape of R(T) transitions. Better agreement with R(T) data can be achieved assuming the existence of short 'weak links' with slightly reduced local critical temperature T c. Hence, one may conclude that an 'exotic' intrinsic electronic inhomogeneity either does not exist in our structures, or, if it does exist, it does not affect their resistive state properties, or does not provide any specific impact distinguishable from conventional weak links.
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Vetter A, Ferrari S, Rath P, Alaee R, Kahl O, Kovalyuk V, et al. Cavity-enhanced and ultrafast superconducting single-photon detectors. Nano Lett. 2016;16(11):7085–92.
Abstract: Ultrafast single-photon detectors with high efficiency are of utmost importance for many applications in the context of integrated quantum photonic circuits. Detectors based on superconductor nanowires attached to optical waveguides are particularly appealing for this purpose. However, their speed is limited because the required high absorption efficiency necessitates long nanowires deposited on top of the waveguide. This enhances the kinetic inductance and makes the detectors slow. Here, we solve this problem by aligning the nanowire, contrary to usual choice, perpendicular to the waveguide to realize devices with a length below 1 mum. By integrating the nanowire into a photonic crystal cavity, we recover high absorption efficiency, thus enhancing the detection efficiency by more than an order of magnitude. Our cavity enhanced superconducting nanowire detectors are fully embedded in silicon nanophotonic circuits and efficiently detect single photons at telecom wavelengths. The detectors possess subnanosecond decay ( approximately 120 ps) and recovery times ( approximately 510 ps) and thus show potential for GHz count rates at low timing jitter ( approximately 32 ps). The small absorption volume allows efficient threshold multiphoton detection.
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Murphy A, Semenov A, Korneev A, Korneeva Y, Gol'tsman G, Bezryadin A. Three temperature regimes in superconducting photon detectors: quantum, thermal and multiple phase-slips as generators of dark counts. Sci Rep. 2015;5:10174 (1 to 10).
Abstract: We perform measurements of the switching current distributions of three w approximately 120 nm wide, 4 nm thick NbN superconducting strips which are used for single-photon detectors. These strips are much wider than the diameter of the vortex cores, so they are classified as quasi-two-dimensional (quasi-2D). We discover evidence of macroscopic quantum tunneling by observing the saturation of the standard deviation of the switching distributions at temperatures around 2 K. We analyze our results using the Kurkijarvi-Garg model and find that the escape temperature also saturates at low temperatures, confirming that at sufficiently low temperatures, macroscopic quantum tunneling is possible in quasi-2D strips and can contribute to dark counts observed in single photon detectors. At the highest temperatures the system enters a multiple phase-slip regime. In this range single phase-slips are unable to produce dark counts and the fluctuations in the switching current are reduced.
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