| Records |
| Author |
Murphy, A.; Semenov, A.; Korneev, A.; Korneeva, Y.; Gol’tsman, G.; Bezryadin, A. |
| Title |
Dark counts initiated by macroscopic quantum tunneling in NbN superconducting photon detectors |
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Miscellaneous |
| Year |
2014 |
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arXiv |
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NbN SSPD |
| Abstract |
We perform measurements of the switching current distributions of three w = 120 nm wide, 4 nm thick NbN superconducting strips which are used for single-photon detectors. These strips are much wider than the diameter 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. |
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murphy2014dark |
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1356 |
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Beck, M.; Klammer, M.; Lang, S.; Leiderer, P.; Kabanov, V. V.; Gol’tsman, G. N.; Demsar, J. |
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Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy |
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Miscellaneous |
| Year |
2011 |
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arXiv |
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NbN thin film, energy gap dynamics |
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Using time-domain Terahertz spectroscopy we performed direct studies of the photoinduced suppression and recovery of the superconducting gap in a conventional BCS superconductor NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the bare quasiparticle recombination rate, the Cooper pair-breaking rate and the electron-phonon coupling constant, \lambda = 1.1 +/- 0.1, which is in excellent agreement with theoretical estimates. |
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Duplicated as 641 |
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1388 |
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Pernice, W.; Schuck, C.; Minaeva, O.; Li, M.; Goltsman, G. N.; Sergienko, A. V.; Tang, H. X. |
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High speed and high efficiency travelling wave single-photon detectors embedded in nanophotonic circuits |
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Miscellaneous |
| Year |
2012 |
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arXiv |
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arXiv |
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1108.5299 |
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1-23 |
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optical waveguides, waveguide SSPD, guantum photonics, jitter, detection efficiency |
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Ultrafast, high quantum efficiency single photon detectors are among the most sought-after elements in modern quantum optics and quantum communication. High photon detection efficiency is essential for scalable measurement-based quantum computation, quantum key distribution, and loophole-free Bell experiments. However, imperfect modal matching and finite photon absorption rates have usually limited the maximum attainable detection efficiency of single photon detectors. Here we demonstrate a superconducting nanowire detector atop nanophotonic waveguides which allows us to drastically increase the absorption length for incoming photons. When operating the detectors close to the critical current we achieve high on-chip single photon detection efficiency up to 91% at telecom wavelengths, with uncertainty dictated by the variation of the waveguide photon flux. We also observe remarkably low dark count rates without significant compromise of detection efficiency. Furthermore, our detectors are fully embedded in a scalable silicon photonic circuit and provide ultrashort timing jitter of 18ps. Exploiting this high temporal resolution we demonstrate ballistic photon transport in silicon ring resonators. The direct implementation of such a detector with high quantum efficiency, high detection speed and low jitter time on chip overcomes a major barrier in integrated quantum photonics. |
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845 |
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Sprengers, J.P.; Gaggero, A.; Sahin, D.; Nejad, S. Jahanmiri; Mattioli, F.; Leoni, R.; Beetz, J.; Lermer, M.; Kamp, M.; Höfling, S.; Sanjines, R.; Fiore A. |
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Waveguide single-photon detectors for integrated quantum photonic circuits |
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Conference Article |
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2011 |
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arXiv |
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arXiv |
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1108.5107 |
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1-11 |
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optical waveguides, waveguide SSPD |
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The generation, manipulation and detection of quantum bits (qubits) encoded on single photons is at the heart of quantum communication and optical quantum information processing. The combination of single-photon sources, passive optical circuits and single-photon detectors enables quantum repeaters and qubit amplifiers, and also forms the basis of all-optical quantum gates and of linear-optics quantum computing. However, the monolithic integration of sources, waveguides and detectors on the same chip, as needed for scaling to meaningful number of qubits, is very challenging, and previous work on quantum photonic circuits has used external sources and detectors. Here we propose an approach to a fully-integrated quantum photonic circuit on a semiconductor chip, and demonstrate a key component of such circuit, a waveguide single-photon detector. Our detectors, based on superconducting nanowires on GaAs ridge waveguides, provide high efficiency (20%) at telecom wavelengths, high timing accuracy (60 ps), response time in the ns range, and are fully compatible with the integration of single-photon sources, passive networks and modulators. |
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846 |
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Ovchinnikov, Yu. N.; Varlamov, A. A. |
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Fluctuation-dissipative phenomena in a narrow superconducting channel carrying current below critical |
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2009 |
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arXiv |
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0910.2659v1 |
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1-4 |
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superconducting nanowire, resistance calculation |
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The theory of current transport in a narrow superconducting channel accounting for thermal fluctuations is developed. These fluctuations result in the appearance of small but finite dissipation in the sample. The value of corresponding voltage is found as the function of temperature (close to transition temperature) and arbitrary bias current. It is demonstrated that the value of the activation energy (exponential factor in the Arrenius law) when current approaches to the critical one is proportional to (1-J/Jc)^(5/4). This result is in concordance with the one for the affine phenomenon of the Josephson current decay due to the thermal phase fluctuations, where the activation energy proportional (1-J/J_c)^(3/2)(the difference in the exponents is related to the additional current dependence of the order parameter). Found dependence of the activation energy on current explains the enormous discrepancy between the theoretically predicted before and the experimentally observed broadening of the resistive transition. |
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arXiv:0910.2659v1; 4 pages, 3 figures |
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931 |
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