Korneeva, Y., Sidorova, M., Semenov, A., Krasnosvobodtsev, S., Mitsen, K., Korneev, A., et al. (2016). Comparison of hot-spot formation in NbC and NbN single-photon detectors. IEEE Trans. Appl. Supercond., 26(3), 1–4.
Abstract: We report an experimental investigation of the hot-spot evolution in superconducting single-photon detectors made of disordered superconducting materials with different diffusivity and energy downconversion time values, i.e., 33-nm-thick NbN and 23-nm-thick NbC films. We have demonstrated that, in NbC film, only 405-nm photons produce sufficiently large hot spot to trigger a single-photon response. The dependence of detection efficiency on bias current for 405-nm photons in NbC is similar to that for 3400-nm photons in NbN. In NbC, large diffusivity and downconversion time result in 1-D critical current suppression profile compared with the usual 2-D profile in NbN.
|
Lusche, R., Semenov, A., Korneeva, Y., Trifonov, A., Korneev, A., Gol'tsman, G., et al. (2014). Effect of magnetic field on the photon detection in thin superconducting meander structures. Phys. Rev. B, 89(10), 104513 (1 to 7).
Abstract: We have studied the influence of an externally applied magnetic field on the photon and dark count rates of meander-type niobium nitride superconducting nanowire single-photon detectors. Measurements have been performed at a temperature of 4.2 K, and magnetic fields up to 250 mT have been applied perpendicularly to the meander plane. While photon count rates are field independent at weak applied fields, they show a strong dependence at fields starting from approximately ±25 mT. This behavior, as well as the magnetic field dependence of the dark count rates, is in good agreement with the recent theoretical model of vortex-assisted photon detection and spontaneous vortex crossing in narrow superconducting lines. However, the local reduction of the superconducting free energy due to photon absorption, which is the fitting parameter in the model, increases much slower with the photon energy than the model predicts. Furthermore, changes in the free-energy during photon counts and dark counts depend differently on the current that flows through the meander. This indicates that photon counts and dark counts occur in different parts of the meander.
|
Peltonen, J. T., Astafiev, O. V., Korneeva, Y. P., Voronov, B. M., Korneev, A. A., Charaev, I. M., et al. (2013). Coherent flux tunneling through NbN nanowires. Phys. Rev. B, 88(22), 220506 (1 to 5).
Abstract: We demonstrate evidence of coherent magnetic flux tunneling through superconducting nanowires patterned in a thin highly disordered NbN film. The phenomenon is revealed as a superposition of flux states in a fully metallic superconducting loop with the nanowire acting as an effective tunnel barrier for the magnetic flux, and reproducibly observed in different wires. The flux superposition achieved in the fully metallic NbN rings proves the universality of the phenomenon previously reported for InOx. We perform microwave spectroscopy and study the tunneling amplitude as a function of the wire width, compare the experimental results with theories, and estimate the parameters for existing theoretical models.
|
Lusche, R., Semenov, A., Il'in, K., Korneeva, Y., Trifonov, A., Korneev, A., et al. (2013). Effect of the wire width and magnetic field on the intrinsic detection efficiency of superconducting nanowire single-photon detectors. IEEE Trans. Appl. Supercond., 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.
|
Shcherbatenko, M., Elezov, M., Manova, N., Sedykh, K., Korneev, A., Korneeva, Y., et al. (2021). Single-pixel camera with a large-area microstrip superconducting single photon detector on a multimode fiber. Appl. Phys. Lett., 118(18), 181103.
Abstract: High sensitivity imaging at the level of single photons is an invaluable tool in many areas, ranging from microscopy to astronomy. However, development of single-photon sensitive detectors with high spatial resolution is very non-trivial. Here we employ the single-pixel imaging approach and demonstrate a proof-of-principle single-pixel single-photon imaging setup. We overcome the problem of low light gathering efficiency by developing a large-area microstrip superconducting single photon detector coupled to a multi-mode optical fiber interface. We show that the setup operates well in the visible and near infrared spectrum, and is able to capture images at the single-photon level.
We thank Philipp Zolotov and Pavel Morozov for NbN film fabrication, ARC coating, and fiber coupling of the detector. We also thank Swabian Instruments GmbH and Dr. Helmut Fedder personally for the kindly provided experimental equipment (Time Tagger Ultra 8). The work in the part of SNSPD research and development was supported by the Russian Foundation for Basic Research Project No. 18-29-20100. The work in the part of the optical setup and imaging was supported by Russian Foundation for Basic Research Project No. 20-32-51004.
|
