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Author Murphy, A.; Semenov, A.; Korneev, A.; Korneeva, Y.; Gol'tsman, G.; Bezryadin, A.
Title Three temperature regimes in superconducting photon detectors: quantum, thermal and multiple phase-slips as generators of dark counts Type Journal Article
Year 2015 Publication Sci. Rep. Abbreviated Journal Sci. Rep.
Volume 5 Issue Pages 10174 (1 to 10)
Keywords SPD, SSPD, SNSPD
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.
Address Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2045-2322 ISBN Medium
Area Expedition Conference
Notes PMID:25988591; PMCID:PMC4437302 Approved no
Call Number Serial 1344
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Author Korneev, A. A.; Korneeva, Y. P.; Mikhailov, M. Yu.; Pershin, Y. P.; Semenov, A. V.; Vodolazov, D. Yu.; Divochiy, A. V.; Vakhtomin, Y. B.; Smirnov, K. V.; Sivakov, A. G.; Devizenko, A. Yu.; Goltsman, G. N.
Title Characterization of MoSi superconducting single-photon detectors in the magnetic field Type Journal Article
Year 2015 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.
Volume 25 Issue 3 Pages 2200504 (1 to 4)
Keywords SSPD, SNSPD
Abstract We investigate the response mechanism of nanowire superconducting single-photon detectors (SSPDs) made of amorphous MoxSi1-x. We study the dependence of photon count and dark count rates on bias current in magnetic fields up to 113 mT at 1.7 K temperature. The observed behavior of photon counts is similar to the one recently observed in NbN SSPDs. Our results show that the detecting mechanism of relatively high-energy photons does not involve the vortex penetration from the edges of the film, and on the contrary, the detecting mechanism of low-energy photons probably involves the vortex penetration from the film edges.
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Notes Approved no
Call Number RPLAB @ akorneev @ KorneevIEEE2015 Serial 991
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Author Kozorezov, A. G.; Lambert, C.; Marsili, F.; Stevens, M. J.; Verma, V. B.; Stern, J. A.; Horansky, R.; Dyer, S.; Duff, S.; Pappas, D. P.; Lita, A.; Shaw, M. D.; Mirin, R. P.; Sae Woo Nam
Title Quasiparticle recombination in hotspots in superconducting current-carrying nanowires Type Journal Article
Year 2015 Publication Abbreviated Journal Phys. Rev. B
Volume 92 Issue 6 Pages
Keywords
Abstract We describe a kinetic model of recombination of non-equilibrium quasiparticles generated by single photon absorption in superconducting current-carrying nanowires. The model is developed to interpret two-photon detection experiments in which a single photon does not possess sufficient energy for breaking superconductivity at a fixed low bias current. We show that quasiparticle self- recombination in relaxing hotspot dominates diffusion expansion effects and explains the observed strong bias current, wavelength and temperature dependencies of hotspot relaxation in tungsten silicide superconducting nanowire single-photon detectors.
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN ISBN Medium
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Notes Approved no
Call Number RPLAB @ alex_kazakov @ Serial 1003
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Author Takesue, Hiroki; Dyer, Shellee D.; Stevens, Martin J.; Verma, Varun; Mirin, Richard P.; Nam, Sae Woo
Title Quantum teleportation over 100 km of fiber using highly efficient superconducting nanowire single-photon detectors Type Journal Article
Year 2015 Publication Abbreviated Journal Optica
Volume 2 Issue Pages
Keywords
Abstract Quantum teleportation is an essential quantum operation by which we can transfer an unknown quantum state to a remote location with the help of quantum entanglement and classical communication. Since the first experimental demonstrations using photonic qubits and continuous variables, the distance of photonic quantum teleportation over free-space channels has continued to increase and has reached >100 km. On the other hand, quantum teleportation over optical fiber has been challenging, mainly because the multifold photon detection that inevitably accompanies quantum teleportation experi- ments has been very inefficient due to the relatively low de- tection efficiencies of typical telecom-band single-photon detectors. Here, we report on quantum teleportation over optical fiber using four high-detection-efficiency supercon- ducting nanowire single-photon detectors (SNSPDs). These SNSPDs make it possible to perform highly efficient multi- fold photon measurements, allowing us to confirm that the quantum states of input photons were successfully tele- ported over 100 km of fiber with an average fidelity of 83.7  2.0%.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number RPLAB @ alex_kazakov @ Serial 1004
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Author Takemoto, K.; Nambu, Y.; Miyazawa, T.; Sakuma, Y.; Yamamoto, T.; Yorozu, S.; Arakawa, Y.
Title Quantum key distribution over 120 km using ultrahigh purity single-photon source and superconducting single-photon detectors Type Journal Article
Year 2015 Publication Sci. Rep. Abbreviated Journal
Volume 5 Issue Pages 14383
Keywords SSPD, SNSPD applications, quantum key distribution, QKD
Abstract Advances in single-photon sources (SPSs) and single-photon detectors (SPDs) promise unique applications in the field of quantum information technology. In this paper, we report long-distance quantum key distribution (QKD) by using state-of-the-art devices: a quantum-dot SPS (QD SPS) emitting a photon in the telecom band of 1.5 μm and a superconducting nanowire SPD (SNSPD). At the distance of 100 km, we obtained the maximal secure key rate of 27.6 bps without using decoy states, which is at least threefold larger than the rate obtained in the previously reported 50-km-long QKD experiment. We also succeeded in transmitting secure keys at the rate of 0.307 bps over 120 km. This is the longest QKD distance yet reported by using known true SPSs. The ultralow multiphoton emissions of our SPS and ultralow dark count of the SNSPD contributed to this result. The experimental results demonstrate the potential applicability of QD SPSs to practical telecom QKD networks.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN ISBN Medium
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Notes Approved no
Call Number Serial 1104
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