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Kahl, O., Ferrari, S., Kovalyuk, V., Vetter, A., Lewes-Malandrakis, G., Nebel, C., et al. (2017). Spectrally multiplexed single-photon detection with hybrid superconducting nanophotonic circuits. Optica, 4(5), 557–562.
Abstract: The detection of individual photons by superconducting nanowire single-photon detectors is an inherently binary mechanism, revealing either their absence or presence while concealing their spectral information. For multicolor imaging techniques, such as single-photon spectroscopy, fluorescence resonance energy transfer microscopy, and fluorescence correlation spectroscopy, wavelength discrimination is essential and mandates spectral separation prior to detection. Here, we adopt an approach borrowed from quantum photonic integration to realize a compact and scalable waveguide-integrated single-photon spectrometer capable of parallel detection on multiple wavelength channels, with temporal resolution below 50 ps and dark count rates below 10 Hz at 80% of the devices' critical current. We demonstrate multidetector devices for telecommunication and visible wavelengths, and showcase their performance by imaging silicon vacancy color centers in diamond nanoclusters. The fully integrated hybrid superconducting nanophotonic circuits enable simultaneous spectroscopy and lifetime mapping for correlative imaging and provide the ingredients for quantum wavelength-division multiplexing on a chip.
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Arutyunov, K. Y., Ramos-Alvarez, A., Semenov, A. V., Korneeva, Y. P., An, P. P., Korneev, A. A., et al. (2016). Superconductivity in highly disordered NbN nanowires. Nanotechnol., 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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Vorobyov, V. V., Kazakov, A. Y., Soshenko, V. V., Korneev, A. A., Shalaginov, M. Y., Bolshedvorskii, S. V., et al. (2017). Superconducting detector for visible and near-infrared quantum emitters [Invited]. Opt. Mater. Express, 7(2), 513–526.
Abstract: Further development of quantum emitter based communication and sensing applications intrinsically depends on the availability of robust single-photon detectors. Here, we demonstrate a new generation of superconducting single-photon detectors specifically optimized for the 500–1100 nm wavelength range, which overlaps with the emission spectrum of many interesting solid-state atom-like systems, such as nitrogen-vacancy and silicon-vacancy centers in diamond. The fabricated detectors have a wide dynamic range (up to 350 million counts per second), low dark count rate (down to 0.1 counts per second), excellent jitter (62 ps), and the possibility of on-chip integration with a quantum emitter. In addition to performance characterization, we tested the detectors in real experimental conditions involving nanodiamond nitrogen-vacancy emitters enhanced by a hyperbolic metamaterial.
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Seleznev, V. A., Divochiy, A. V., Vakhtomin, Y. B., Morozov, P. V., Zolotov, P. I., Vasil'ev, D. D., et al. (2016). Superconducting detector of IR single-photons based on thin WSi films. In J. Phys.: Conf. Ser. (Vol. 737, 012032).
Abstract: We have developed the deposition technology of WSi thin films 4 to 9 nm thick with high temperature values of superconducting transition (Tc~4 K). Based on deposed films there were produced nanostructures with indicative planar sizes ~100 nm, and the research revealed that even on nanoscale the films possess of high critical temperature values of the superconducting transition (Tc~3.3-3.7 K) which certifies high quality and homogeneity of the films created. The first experiments on creating superconducting single-photon detectors showed that the detectors' SDE (system detection efficiency) with increasing bias current (I b) reaches a constant value of ~30% (for X=1.55 micron) defined by infrared radiation absorption by the superconducting structure. To enhance radiation absorption by the superconductor there were created detectors with cavity structures which demonstrated a practically constant value of quantum efficiency >65% for bias currents Ib>0.6-Ic. The minimal dark counts level (DC) made 1 s-1 limited with background noise. Hence WSi is the most promising material for creating single-photon detectors with record SDE/DC ratio and noise equivalent power (NEP).
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Shcherbatenko, M., Lobanov, Y., Semenov, A., Kovalyuk, V., Korneev, A., Ozhegov, R., et al. (2016). Potential of a superconducting photon counter for heterodyne detection at the telecommunication wavelength. Opt. Express, 24(26), 30474–30484.
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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Peltonen, J. T., Peng, Z. H., Korneeva, Y. P., Voronov, B. M., Korneev, A. A., Semenov, A. V., et al. (2016). Coherent dynamics and decoherence in a superconducting weak link. Physic. Rev. B,, 94, 180508.
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Goltsman, G. N., Samartsev, V. V., Vinogradov, E. A., Naumov, A. V., & Karimullin, K. R. (2015). New generation of superconducting nanowire single-photon detectors. In EPJ Web of Conferences (Vol. 103, 01006 (1 to 2)).
Abstract: We present an overview of recent results for new generation of infrared and optical superconducting nanowire single-photon detectors (SNSPDs) that has already demonstrated a performance that makes them devices-of-choice for many applications. SNSPDs provide high efficiency for detecting individual photons while keeping dark counts and timing jitter minimal. Besides superior detection performance over a broad optical bandwidth, SNSPDs are also compatible with an integrated optical platform as a crucial requirement for applications in emerging quantum photonic technologies. By embedding SNSPDs in nanophotonic circuits we realize waveguide integrated single photon detectors which unite all desirable detector properties in a single device.
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Galin, M. A., Klushin, A. M., Kurin, V. V., Seliverstov, S. V., Finkel, M. I., Goltsman, G. N., et al. (2015). Towards local oscillators based on arrays of niobium Josephson junctions. Supercond. Sci. Technol., 28(5), 055002 (1 to 7).
Abstract: Various applications in the field of terahertz technology are in urgent need of compact, wide-tunable solid-state continuous wave radiation sources with a moderate power. However, satisfactory solutions for the THz frequency range are scarce yet. Here we report on coherent radiation from a large planar array of Josephson junctions (JJs) in the frequency range between 0.1 and 0.3 THz. The external resonator providing the synchronization of JJ array is identified as a straight fragment of a single-strip-line containing the junctions themselves. We demonstrate a prototype of the quasioptical heterodyne receiver with the JJ array as a local oscillator and a hot-electron bolometer mixer.
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Korneev, A., Golt'sman, G., & Pernice, W. (2015). Photonic integration meets single-photon detection (Vol. 51).
Abstract: By embedding superconducting nanowire single-photon detectors (SNSPDs) in nanophotonic circuits, these waveguide-integrated detectors are a key building block for future on-chip quantum computing applications.
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Florya, I. N., Korneeva, Y. P., Sidorova, M. V., Golikov, A. D., Gaiduchenko, I. A., Fedorov, G. E., et al. (2015). Energy relaxtation and hot spot formation in superconducting single photon detectors SSPDs. In EPJ Web of Conferences (Vol. 103, 10004 (1 to 2)).
Abstract: We have studied the mechanism of energy relaxation and resistive state formation after absorption of a single photon for different wavelengths and materials of single photon detectors. Our results are in good agreement with the hot spot model.
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