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Author Esteban, Eduin; Serna, Hernandez
Title Quantum key distribution protocol with private-public key Type Journal Article
Year 2009 Publication arXiv Abbreviated Journal arXiv
Volume Issue Pages 3
Keywords quantum cryptography; QKD; protocol
Abstract (up) A quantum cryptographic protocol based in public key cryptography combinations and private key cryptography is presented. Unlike the BB84 protocol 1 and its many variants 2,3 two quantum channels are used. The present research does not make reconciliation mechanisms of information to derive the key. A three related system of key distribution are described.
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Notes arXiv: 0908.2146 Approved no
Call Number RPLAB @ gujma @ Serial 756
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Author 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.
Title Waveguide single-photon detectors for integrated quantum photonic circuits Type Journal Article
Year 2011 Publication arXiv Abbreviated Journal arXiv
Volume Issue Pages 11
Keywords SPD
Abstract (up) he 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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Publisher Place of Publication arXiv:1108.5107 Editor
Language Summary Language Original Title
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Notes Approved no
Call Number RPLAB @ gujma @ Serial 668
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Author Baeva, E. M.; Titova, N. A.; Veyrat, L.; Sacépé, B.; Semenov, A. V.; Goltsman, G. N.; Kardakova, A. I.; Khrapai, V. S.
Title Thermal relaxation in metal films bottlenecked by diffuson lattice excitations of amorphous substrates Type Miscellaneous
Year 2021 Publication arXiv Abbreviated Journal arXiv
Volume Issue Pages
Keywords metal films, NbN, InOx, Au/Ni, thermal relaxation
Abstract (up) Here we examine the role of the amorphous insulating substrate in the thermal relaxation in thin NbN, InOx, and Au/Ni films at temperatures above 5 K. The studied samples are made up of metal bridges on an amorphous insulating layer lying on or suspended above a crystalline substrate. Noise thermometry was used to measure the electron temperature Te of the films as a function of Joule power per unit of area P2D. In all samples, we observe the dependence P2D∝Tne with the exponent n≃2, which is inconsistent with both electron-phonon coupling and Kapitza thermal resistance. In suspended samples, the functional dependence of P2D(Te) on the length of the amorphous insulating layer is consistent with the linear T-dependence of the thermal conductivity, which is related to lattice excitations (diffusons) for the phonon mean free path smaller than the dominant phonon wavelength. Our findings are important for understanding the operation of devices embedded in amorphous dielectrics.
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Notes Approved no
Call Number Serial 1163
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Author Amundsen, Morten; Linder, Jacob
Title General solution of 2D and 3D superconducting quasiclassical systems: coalescing vortices and nanodisk geometries Type Journal Article
Year 2015 Publication arXiv:1512.00030 [cond-mat.supr-con] Abbreviated Journal
Volume Issue Pages
Keywords quasiclassical Usadel equation, finite elements method
Abstract (up) In quasiclassical Keldysh theory, the Green function matrix g<cb><2021> is used to compute a variety of physical quantities in mesoscopic systems. However, solving the set of non-linear differential equations that provide g<cb><2021> becomes a challenging task when going to higher spatial dimensions than one. Such an extension is crucial in order to describe physical phenomena like charge/spin Hall effects and topological excitations like vortices and skyrmions, none of which can be captured in one-dimensional models. We here present a numerical finite element method which solves the 2D and 3D quasiclassical Usadel equation, without any linearisation, relevant for the diffusive regime. We show the application of this on two model systems with non-trivial geometries: (i) a bottlenecked Josephson junction with external flux and (ii) a nanodisk ferromagnet deposited on top of a superconductor. We demonstrate that it is possible to control externally not only the geometrical array in which superconducting vortices arrange themselves, but also to cause coalescence and thus tune the number of vortices. The finite element method presented herein could pave the way for gaining insight in physical phenomena which so far have remained largely unexplored due to the complexity of solving the full quasiclassical equations in higher dimensions.
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Notes Approved no
Call Number Serial 1066
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Author Engel, Andreas; Aeschbacher, Adrian; Inderbitzin, Kevin; Schilling, Andreas; Il'in, Konstantin; Hofherr, Matthias; Siegel, Michael; Semenov, Alexei; Hübers, Heinz-Wilhelm
Title Tantalum nitride superconducting single-photon detectors with low cut-off energy Type Journal Article
Year 2011 Publication arXiv Abbreviated Journal arXiv
Volume Issue Pages 9
Keywords SSPD
Abstract (up) Materials with a small superconducting energy gap favor a high detection efficiency of low-energy photons in superconducting nanowire single-photon detectors. We developed a TaN detector with smaller gap and lower density of states at the Fermi energy than in comparable NbN devices, while other relevant parameters remain essentially unchanged. This results in a reduction of the minimum photon energy required for direct detection to $\approx1/3$ as compared to NbN.
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Publisher Place of Publication arXiv:1110.4576 Editor
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 @ gujma @ Serial 687
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Author Mazin, Benjamin A.; Bumble, Bruce; Meeker, Seth R.; O'Brien, Kieran; McHugh, Sean; Langman, Eric
Title A superconducting focal plane array for ultraviolet, optical, and near-infrared astrophysics Type Journal Article
Year 2011 Publication arXiv Abbreviated Journal arXiv
Volume Issue Pages 9
Keywords
Abstract (up) Microwave Kinetic Inductance Detectors, or MKIDs, have proven to be a powerful cryogenic detector technology due to their sensitivity and the ease with which they can be multiplexed into large arrays. A MKID is an energy sensor based on a photon-variable superconducting inductance in a lithographed microresonator, and is capable of functioning as a photon detector across the electromagnetic spectrum as well as a particle detector. Here we describe the first successful effort to create a photon-counting, energy-resolving ultraviolet, optical, and near infrared MKID focal plane array. These new Optical Lumped Element (OLE) MKID arrays have significant advantages over semiconductor detectors like charge coupled devices (CCDs). They can count individual photons with essentially no false counts and determine the energy and arrival time of every photon with good quantum efficiency. Their physical pixel size and maximum count rate is well matched with large telescopes. These capabilities enable powerful new astrophysical instruments usable from the ground and space. MKIDs could eventually supplant semiconductor detectors for most astronomical instrumentation, and will be useful for other disciplines such as quantum optics and biological imaging.
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Publisher Place of Publication eprint arXiv:1112.0004 Editor
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Notes Approved no
Call Number RPLAB @ gujma @ Serial 698
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Author Jian Wei; David Olaya; Boris Karasik; Sergey Pereverzev; Andrei Sergeev; Michael Gershenson
Title Ultra-sensitive hot-electron nanobolometers for terahertz astrophysics Type Journal Article
Year 2007 Publication ArXiv e-prints Abbreviated Journal
Volume 710 Issue Pages
Keywords cond-mat.other; astro-ph; cond-mat.mes-hall
Abstract (up) The background-limited spectral imaging of the early Universe requires spaceborne terahertz (THz) detectors with the sensitivity 2-3 orders of magnitude better than that of the state-of-the-art bolometers. To realize this sensitivity without sacrificing operating speed, novel detector designs should combine an ultrasmall heat capacity of a sensor with its unique thermal isolation. Quantum effects in thermal transport at nanoscale put strong limitations on the further improvement of traditional membrane-supported bolometers. Here we demonstrate an innovative approach by developing superconducting hot-electron nanobolometers in which the electrons are cooled only due to a weak electron-phonon interaction. At T<0.1K, the electron-phonon thermal conductance in these nanodevices becomes less than one percent of the quantum of thermal conductance. The hot-electron nanobolometers, sufficiently sensitive for registering single THz photons, are very promising for submillimeter astronomy and other applications based on quantum calorimetry and photon counting.
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Notes arXiv:0710.5474v1; 19 pages, 3 color figures Approved no
Call Number RPLAB @ s @ Serial 407
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Author Kahl, O.; Ferrari, S.; Kovalyuk, V.; Vetter, A.; Lewes-Malandrakis, G.; Nebel, C.; Korneev, A.; Goltsman, G.; Pernice, W.
Title Spectrally resolved single-photon imaging with hybrid superconducting – nanophotonic circuits Type Miscellaneous
Year 2016 Publication arXiv Abbreviated Journal arXiv
Volume Issue Pages 1-20
Keywords waiveguide SSPD, SNSPD, imaging
Abstract (up) The detection of individual photons is an inherently binary mechanism, revealing either their absence or presence while concealing their spectral information. For multi-color 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. We demonstrate multi-detector 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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Notes Approved no
Call Number Serial 1334
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Author 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.
Title Waveguide single-photon detectors for integrated quantum photonic circuits Type Conference Article
Year 2011 Publication arXiv Abbreviated Journal arXiv
Volume 1108.5107 Issue Pages 1-11
Keywords optical waveguides, waveguide SSPD
Abstract (up) 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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Publisher Place of Publication Editor
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Series Editor Series Title Abbreviated Series Title
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Area Expedition Conference
Notes Approved no
Call Number Serial 846
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Author Ovchinnikov, Yu. N.; Varlamov, A. A.
Title Fluctuation-dissipative phenomena in a narrow superconducting channel carrying current below critical Type Journal Article
Year 2009 Publication arXiv Abbreviated Journal
Volume 0910.2659v1 Issue Pages 1-4
Keywords superconducting nanowire, resistance calculation
Abstract (up) 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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Notes arXiv:0910.2659v1; 4 pages, 3 figures Approved no
Call Number Serial 931
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