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Vodolazov DY, Korneeva YP, Semenov AV, Korneev AA, Goltsman GN. Vortex-assisted mechanism of photon counting in a superconducting nanowire single-photon detector revealed by external magnetic field. Phys Rev B. 2015;92(10):104503 (1 to 9).
Abstract: We use an external magnetic field to probe the detection mechanism of a superconducting nanowire single-photon detector. We argue that the hot belt model (which assumes partial suppression of the superconducting order parameter Δ across the whole width of the superconducting nanowire after absorption of the photon) does not explain observed weak-field dependence of the photon count rate (PCR) for photons with λ=450nm and noticeable decrease of PCR (with increasing the magnetic field) in a range of the currents for photons with wavelengths λ=450–1200nm. Found experimental results for all studied wavelengths can be explained by the vortex hot spot model (which assumes partial suppression of Δ in the area with size smaller than the width of the nanowire) if one takes into account nucleation and entrance of the vortices to the photon induced hot spot and their pinning by the hot spot with relatively large size and strongly suppressed Δ.
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Lusche R, Semenov A, Il'in K, Korneeva Y, Trifonov A, Korneev A, et al. Effect of the wire width and magnetic field on the intrinsic detection efficiency of superconducting nanowire single-photon detectors. IEEE Trans Appl Supercond. 2013;23(3):2200205.
Abstract: We present thorough measurements of the intrinsic detection efficiency in the wavelength range from 350 to 2500 nm for meander-type TaN and NbN superconducting nanowire single-photon detectors with different widths of the nanowire. The width varied from 70 nm to 130 nm. The open-beam configuration allowed us to accurately normalize measured spectra and to extract the intrinsic detection efficiency. For detectors from both materials the intrinsic detection efficiency at short wavelengths amounts at 100% and gradually decreases at wavelengths larger than the specific cut-off wavelengths, which decreases with the width of the nanowire. Furthermore, we show that applying weak magnetic fields perpendicular to the meander plane decreases the smallest detectable photon flux.
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Minaeva O, Divochiy A, Korneev A, Sergienko AV, Goltsman GN. High speed infrared photon counting with photon number resolving superconducting single-photon detectors (SSPDs). In: CLEO/Europe – EQEC.; 2009.
Abstract: A review of development and characterization of the nanostructures consisting of several meander sections, all connected in parallel was presented. Such geometry leads to a significant decrease of the kinetic inductance, without a decrease of the SSPD active area. A new type of SSPDs possess the QE of large-active- area devices, but, simultaneously, allows achieving short response times and the GHz-counting rate. This new generation of superconducting detectors has another significant advantage for quantum key distribution, they have a photon number resolving capability and can distinguish more photons.
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Mohan N, Minaeva O, Gol'tsman GN, Nasr MB, Saleh BE, Sergienko AV, et al. Photon-counting optical coherence-domain reflectometry using superconducting single-photon detectors. Opt Express. 2008;16(22):18118–30.
Abstract: We consider the use of single-photon counting detectors in coherence-domain imaging. Detectors operated in this mode exhibit reduced noise, which leads to increased sensitivity for weak light sources and weakly reflecting samples. In particular, we experimentally demonstrate the possibility of using superconducting single-photon detectors (SSPDs) for optical coherence-domain reflectometry (OCDR). These detectors are sensitive over the full spectral range that is useful for carrying out such imaging in biological samples. With counting rates as high as 100 MHz, SSPDs also offer a high rate of data acquisition if the light flux is sufficient.
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Nasr MB, Minaeva O, Goltsman GN, Sergienko AV, Saleh BE, Teich MC. Submicron axial resolution in an ultrabroadband two-photon interferometer using superconducting single-photon detectors. Opt Express. 2008;16(19):15104–8.
Abstract: We generate ultrabroadband biphotons via the process of spontaneous parametric down-conversion in a quasi-phase-matched nonlinear grating that has a linearly chirped poling period. Using these biphotons in conjunction with superconducting single-photon detectors (SSPDs), we measure the narrowest Hong-Ou-Mandel dip to date in a two-photon interferometer, having a full width at half maximum (FWHM) of approximately 5.7 fsec. This FWHM corresponds to a quantum optical coherence tomography (QOCT) axial resolution of 0.85 µm. Our results indicate that a high flux of nonoverlapping biphotons may be generated, as required in many applications of nonclassical light.
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