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Sample records for v-groove quantum wires

  1. Optical spectroscopy of GaAs/AlGaAs V-groove quantum wires Quantum wells

    CERN Document Server

    Roshan, R

    2001-01-01

    In this thesis we report on optical spectroscopy of GaAs/AIGaAs quantum wires (QWRs), grown on pre-patterned semi-insulating GaAs (100) substrates by low-pressure metal organic vapour phase epitaxy (LP-MOVPE). Crescent-shaped quantum wires develop at the bottom of the grooves by self-organisation when a GaAs quantum well embedded in Al sub 0 sub . sub 3 Ga sub 0 sub . sub 7 As barriers was overgrown on the patterned surface. The overgrowth also resulted in the formation of vertical quantum wells (VQWs) in the AIGaAs barriers and sidewall quantum wells (SQWs) on the (111) surfaces that define the grooves. A narrow constriction (pinch-off) separates the QWRs from the side walls and provides two-dimensional confinement in them. Several types of wire arrangements are investigated in detail which includes single QWR, vertical stacked QWRs, lateral arrays of wires with sub-mu m pitch and gated QWRs. Both conventional far-field and near-field spectroscopic techniques are used to study these wires. A low-temperature ...

  2. Transport in quantum wires

    Indian Academy of Sciences (India)

    This motivated us to study the LL model of a quantum wire, with Fermi liquid leads and the unusual feature of ... of quantized conductance even in clean quantum wires and a novel odd–even effect in the presence of a .... But in one dimension, it is well-known that the FL theory breaks down, and the ground state is a ...

  3. InP/InAlAs/InGaAs-quantum wires

    Energy Technology Data Exchange (ETDEWEB)

    Kappelt, M.; Tuerck, V.; Grundmann, M.; Bimberg, D. [Technische Univ., Berlin (Germany); Cerva, H. [Siemens AG, Muenchen (Germany)

    1996-12-31

    Single InGaAs quantum wires and stacked InGaAs quantum wires with InAlAs barriers have been fabricated on v-grooved InP substrates by low pressure metal-organic chemical vapor deposition. The authors have found growth conditions where the InAlAs barrier exhibits a resharpening effect, similar to that of AlgaAs utilized for growth on GaAs substrates. The existence of structural and electronic quantum wires in the bottom of the grooves is proven.

  4. Anisotropic carrier and exciton confinement in T-shaped quantum wires revealed by magneto-photoluminescence

    DEFF Research Database (Denmark)

    Langbein, Wolfgang Werner; Gislason, Hannes; Hvam, Jørn Märcher

    1998-01-01

    The realization of one-dimensional (1D) semiconductor nanostructures with large confinement energies is of importance for device applications. Different techniques such as growth on tilted substrates (Serpentine superlattices) or prepatterned substrates (V-groove quantum wires) and the cleaved-ed...... was revealed by magneto-photoluminescence. We determine here the extension of the T-shaped quantum wire (T-QWR) state in both confining directions [110] and [001] to verify its 1D character, as shown for crescent-shaped wires...

  5. Quantum conductance in silicon quantum wires

    CERN Document Server

    Bagraev, N T; Klyachkin, L E; Malyarenko, A M; Gehlhoff, W; Ivanov, V K; Shelykh, I A

    2002-01-01

    The results of investigations of electron and hole quantum conductance staircase in silicon quantum wires are presented. The characteristics of self-ordering quantum wells of n- and p-types, which from on the silicon (100) surface in the nonequilibrium boron diffusion process, are analyzed. The results of investigations of the quantum conductance as the function of temperature, carrier concentration and modulation degree of silicon quantum wires are given. It is found out, that the quantum conductance of the one-dimensional channels is observed, for the first time, at an elevated temperature (T >= 77 K)

  6. Transparency in nanophotonic quantum wires

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mahi R [Department of Physics and Astronomy, University of Western Ontario, London N6A 3K7 (Canada)

    2009-03-28

    We have studied the quantum optics of a photonic quantum nanowire doped with an ensemble of three-level nanoparticles. The wire is made from two photonic crystals A and B. Crystal A is embedded within crystal B and acts as a photonic nanowire. It is considered that the conduction band of crystal A lies below that of crystal B. As a result, photons are confined in crystal A and are reflected from crystal B. The bound states of the confined photons are calculated using the transfer matrix method. It is found that the number of bound states in the wire depends on the size of the wire and the energy difference between the conduction band extrema of crystals A and B. The absorption coefficient of the system has also been calculated using the Schroedinger equation method. It is considered that the nanoparticles interact with the photonic bound states. Numerical simulations show that when one of the resonance energies lies near the bound state, the system becomes transparent. However, when the resonance energy lies away from the bound state the crystal reverts to an absorbing state. Similarly, when the radius of the dielectric spheres is changed the location of the transparency peak is shifted. This means that the present system can be switched between two states by changing the size of the wire and the transition energy. These findings can be used to make new types of optical devices.

  7. Lasing from a single quantum wire

    OpenAIRE

    Hayamizu, Yuhei; Yoshita, Masahiro; Watanabe, Shinichi; Akiyama, Hidefumi; Pfeiffer, Loren N.; West, Ken W.

    2002-01-01

    A laser with an active volume consisting of only a single quantum wire in the 1-dimensional (1-D) ground state is demonstrated. The single wire is formed quantum-mechanically at the T-intersection of a 14 nm Al_{0.07}Ga_{0.93}As quantum well and a 6 nm GaAs quantum well, and is embedded in a 1-D single-mode optical waveguide. We observe single-mode lasing from the quantum wire ground state by optical pumping. The laser operates from 5 to 60 K, and has a low threshold pumping power of 5 mW at ...

  8. Growing InGaAs quasi-quantum wires inside semi-rhombic shaped planar InP nanowires on exact (001) silicon

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yu; Li, Qiang; Lau, Kei May, E-mail: eekmlau@ust.hk [Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Chang, Shih-Pang; Hsu, Wen-Da [National Nano Device Laboratories, Narlabs, Hsinchu 300, Taiwan (China)

    2016-06-13

    We report InGaAs quasi-quantum wires embedded in planar InP nanowires grown on (001) silicon emitting in the 1550 nm communication band. An array of highly ordered InP nanowire with semi-rhombic cross-section was obtained in pre-defined silicon V-grooves through selective-area hetero-epitaxy. The 8% lattice mismatch between InP and Si was accommodated by an ultra-thin stacking disordered InP/GaAs nucleation layer. X-ray diffraction and transmission electron microscope characterizations suggest excellent crystalline quality of the nanowires. By exploiting the morphological evolution of the InP and a self-limiting growth process in the V-grooves, we grew embedded InGaAs quantum-wells and quasi-quantum-wires with tunable shape and position. Room temperature analysis reveals substantially improved photoluminescence in the quasi-quantum wires as compared to the quantum-well reference, due to the reduced intrusion defects and enhanced quantum confinement. These results show great promise for integration of III-V based long wavelength nanowire lasers on the well-established (001) Si platform.

  9. Electronic Properties of Quantum Wire Networks

    OpenAIRE

    Kuzmenko, Igor

    2005-01-01

    Quantum wire networks (``quantum crossbars'', QCB) represent a 2D grid formed by superimposed crossing arrays of parallel conducting quantum wires, molecular chains or metallic single-wall carbon nanotubes. QCB coupled only by capacitive interaction in the crosses have similar low-energy, long-wave properties characterized as a crossed sliding Luttinger liquid (CSLL) phase. In this Thesis we develop a theory of interacting Bose excitations (plasmons) in QCB. We analyze spectrum of boson field...

  10. Charge transport through single molecules, quantum dots and quantum wires.

    Science.gov (United States)

    Andergassen, S; Meden, V; Schoeller, H; Splettstoesser, J; Wegewijs, M R

    2010-07-09

    We review recent progress in the theoretical description of correlation and quantum fluctuation phenomena in charge transport through single molecules, quantum dots and quantum wires. Various physical phenomena are addressed, relating to cotunneling, pair-tunneling, adiabatic quantum pumping, charge and spin fluctuations, and inhomogeneous Luttinger liquids. We review theoretical many-body methods to treat correlation effects, quantum fluctuations, non-equilibrium physics, and the time evolution into the stationary state of complex nanoelectronic systems.

  11. V-groove plasmonic waveguides fabricated by nanoimprint lithography

    DEFF Research Database (Denmark)

    Fernandez-Cuesta, I.; Nielsen, R.B.; Boltasseva, Alexandra

    2007-01-01

    Propagation of channel plasmon-polariton modes in the bottom of a metal V groove has been recently demonstrated. It provides a unique way of manipulating light at nanometer length scale. In this work, we present a method based on nanoimprint lithography that allows parallel fabrication of integra......Propagation of channel plasmon-polariton modes in the bottom of a metal V groove has been recently demonstrated. It provides a unique way of manipulating light at nanometer length scale. In this work, we present a method based on nanoimprint lithography that allows parallel fabrication...... of integrated optical devices composed of metal V grooves. This method represents an improvement with respect to previous works, where the V grooves were fabricated by direct milling of the metal, in terms of robustness and throughput. © 2007 American Vacuum Society...

  12. High resolution STEM of quantum dots and quantum wires

    DEFF Research Database (Denmark)

    Kadkhodazadeh, Shima

    2013-01-01

    This article reviews the application of high resolution scanning transmission electron microscopy (STEM) to semiconductor quantum dots (QDs) and quantum wires (QWRs). Different imaging and analytical techniques in STEM are introduced and key examples of their application to QDs and QWRs...

  13. Bragg grating filters in plasmonic V-groove waveguides

    DEFF Research Database (Denmark)

    Smith, Cameron; Desiatov, Boris; Goykhmann, Ilya

    2012-01-01

    We demonstrate spectral filtering via Bragg gratings in plasmonic V-groove waveguides. Transmission spectra of wafer-scale fabricated devices exhibit 8.2 dB extinction ratio with 39.9 nm bandwidth. Near-field measurements verify spectral rejection.......We demonstrate spectral filtering via Bragg gratings in plasmonic V-groove waveguides. Transmission spectra of wafer-scale fabricated devices exhibit 8.2 dB extinction ratio with 39.9 nm bandwidth. Near-field measurements verify spectral rejection....

  14. Channel plasmon polariton propagation in nanoimprinted V-groove waveguides

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Bundgaard; Fernandez-Cuesta, I.; Boltasseva, Alexandra

    2008-01-01

    We present the results of optical characterization of metal V-groove waveguides using scanning near-field microscopy, showing broadband transmission with subwavelength confinement and propagation lengths exceeding 100 mu m. An updated fabrication method using a combination of UV and nanoimprint l...

  15. Quantum optics with quantum dots in photonic wires

    DEFF Research Database (Denmark)

    Munsch, Mathieu; Cadeddu, Davide; Teissier, Jean

    2016-01-01

    We present an exploration of the spectroscopy of a single quantum dot in a photonic wire. The device presents a high photon extraction efficiency, and strong hybrid coupling to mechanical modes. We use resonance fluorescence to probe the emitter's properties with the highest sensitivity, allowing...... the detection of thermal excitation of the mechanical mode at 4 K....

  16. Superconductivity in quantum wires: A symmetry analysis

    Science.gov (United States)

    Samokhin, K. V.

    2017-10-01

    We study properties of quantum wires with spin-orbit coupling and time reversal symmetry breaking, in normal and superconducting states. Electronic band structures are classified according to quasi-one-dimensional magnetic point groups, or magnetic classes. The latter belong to one of three distinct types, depending on the way the time reversal operation appears in the group elements. The superconducting gap functions are constructed using antiunitary operations and have different symmetry properties depending on the type of the magnetic point group. We obtain the spectrum of the Andreev boundary modes near the end of the wire in a model-independent way, using the semiclassical approach with the boundary conditions described by a phenomenological scattering matrix. Explicit expressions for the bulk topological invariants controlling the number of the boundary zero modes are presented in the general multiband case for two types of the magnetic point groups with real order parameters, corresponding to DIII and BDI symmetry classes.

  17. V-groove gratings on silicon for infrared beam splitting.

    Science.gov (United States)

    Rajkumar, N; McMullin, J N

    1995-05-10

    Infrared beam-splitting transmission gratings that utilize anisotropically etched v-grooves on silicon wafers are proposed. With scalar diffraction theory to find the amplitudes of the different diffraction orders, a numerical search is used to find optimum designs for 1:3, 1:5, and 1:7 splitters with efficiencies greater than 70% with a standard deviation in intensity of no more than 7%.

  18. Tailoring channeled plasmon polaritons in metallic V-grooves

    DEFF Research Database (Denmark)

    Smith, Cameron; Thilsted, Anil Haraksingh; Marie, Rodolphe

    2013-01-01

    Channeled plasmon polaritons (CPPs) are electromagnetic excitations that are bound to and propagate along metallic V-groove waveguides [1]. CPPs offer subwavelength lateral confinement, an ability to turn sharp bends with near-zero loss and are considered to be one of the most suitable forms of p...... on the optimisation of their properties (e.g. propagation length, confinement) and improving both the quality and cost of fabrication techniques [4]. © 2013 IEEE....

  19. Quantum photonics with quantum dots in photonic wires

    DEFF Research Database (Denmark)

    Munsch, Mathieu; Kuhlmann, Andreas; Cadeddu, Davide

    2016-01-01

    We present results from the spectroscopy of a single quantum dot in a photonic wire. The device presents a high photon extraction efficiency, and strong hybrid coupling to mechanical modes. We use resonance fluorescence to probe the emitter’s properties with the highest sensitivity. Weperform...... a detailed analysis of the noise in the device and reveal in particular the thermal excitation of mechanical modes at 4 K....

  20. Nonequilibrium functional bosonization of quantum wire networks

    Energy Technology Data Exchange (ETDEWEB)

    Ngo Dinh, Stephane, E-mail: stephane.ngodinh@kit.edu [Institut fuer Theorie der Kondensierten Materie, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany); DFG Center for Functional Nanostructures, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany); Bagrets, Dmitry A. [Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany); Mirlin, Alexander D. [Institut fuer Theorie der Kondensierten Materie, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany); Institut fuer Nanotechnologie, Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany); DFG Center for Functional Nanostructures, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany); Petersburg Nuclear Physics Institute, 188300 St. Petersburg (Russian Federation)

    2012-11-15

    We develop a general approach to nonequilibrium nanostructures formed by one-dimensional channels coupled by tunnel junctions and/or by impurity scattering. The formalism is based on nonequilibrium version of functional bosonization. A central role in this approach is played by the Keldysh action that has a form reminiscent of the theory of full counting statistics. To proceed with evaluation of physical observables, we assume the weak-tunneling regime and develop a real-time instanton method. A detailed exposition of the formalism is supplemented by two important applications: (i) tunneling into a biased Luttinger liquid with an impurity, and (ii) quantum Hall Fabry-Perot interferometry. - Highlights: Black-Right-Pointing-Pointer A nonequilibrium functional bosonization framework for quantum wire networks is developed Black-Right-Pointing-Pointer For the study of observables in the weak tunneling regime a real-time instanton method is elaborated. Black-Right-Pointing-Pointer We consider tunneling into a biased Luttinger liquid with an impurity. Black-Right-Pointing-Pointer We analyze electronic Fabry-Perot interferometers in the integer quantum Hall regime.

  1. Bound Electron States in Skew-symmetric Quantum Wire Intersections

    Science.gov (United States)

    2014-01-01

    for electronic transport studies was to confine resonant- tunneling heterostructures laterally with a fabrication-imposed po- tential. This approach...Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 Quantum Wires, Crossed Nanowires , Trapped Electron States, Quantum Dots REPORT...realistic systems such as semiconductor nanowire films and carbon nanotube bundles. Bound electron states in skew-symmetric quantum wire intersections by

  2. Peltier effect in strongly driven quantum wires

    Science.gov (United States)

    Mierzejewski, M.; Crivelli, D.; Prelovšek, P.

    2014-08-01

    We study a microscopic model of a thermocouple device with two connected correlated quantum wires driven by a constant electric field. In such a closed system we follow the time and position dependence of the entropy density using the concept of the reduced density matrix. At weak driving, the initial changes of the entropy at the junctions can be described by the linear Peltier response. At longer times the quasiequilibrium situation is reached with well defined local temperatures which increase due to an overall Joule heating. On the other hand, a strong electric field induces a nontrivial nonlinear thermoelectric response, e.g., the Bloch oscillations of the energy current. Moreover, we show for the doped Mott insulators that strong driving can reverse the Peltier effect.

  3. Biexciton binding energy in ZnSe quantum wells and quantum wires

    DEFF Research Database (Denmark)

    Wagner, Hans-Peter; Langbein, Wolfgang; Hvam, Jørn Märcher

    2002-01-01

    The biexciton binding energy E-XX is investigated in ZnSe/ZnMgSe quantum wells and quantum wires as a function of the lateral confinement by transient four-wave mixing. In the quantum wells one observes for decreasing well width a significant increase in the relative binding energy, saturating...... for well widths less than 8 nm. In the quantum wires an increase of 30% is found in the smallest quantum wire structures compared to the corresponding quantum well value. A simple analytical model taking into account the quantum confinement in these low-dimensional systems is used to explain...

  4. Theory of Spin Seebeck Effects in a Quantum Wire

    Science.gov (United States)

    Ogata, Masao; Fukuyama, Hidetoshi

    2017-09-01

    Spin Seebeck coefficient in a quantum wire is microscopically derived using the Kubo formula and thermal Green’s functions, taking account of the effects of disorder in a self-consistent t-matrix approximation. It is found that the induced spin current to be detected through the inverse spin Hall effect will be in the range of experimental detectability when the chemical potential for electrons in the quantum wire is close to the band edge.

  5. Spectrum of localized states in graphene quantum dots and wires

    Energy Technology Data Exchange (ETDEWEB)

    Zalipaev, V.V. [Department of Mathematical Sciences, Loughborough University, Leicestershire, LE11 3TU (United Kingdom); Maksimov, D.N. [LV Kirensky Institute of Physics, Krasnoyarsk 660036 (Russian Federation); Linton, C.M. [Department of Mathematical Sciences, Loughborough University, Leicestershire, LE11 3TU (United Kingdom); Kusmartsev, F.V., E-mail: F.Kusmartsev@lboro.ac.uk [Department of Physics, Loughborough University, Leicestershire, LE11 3TU (United Kingdom)

    2013-01-03

    We developed semiclassical method and show that any smooth potential in graphene describing elongated a quantum dot or wire may behave as a barrier or as a trapping well or as a double barrier potential, Fabry–Perot structure, for 1D Schrödinger equation. The energy spectrum of quantum wires has been found and compared with numerical simulations. We found that there are two types of localized states, stable and metastable, having finite life time. These life times are calculated, as is the form of the localized wave functions which are exponentially decaying away from the wire in the perpendicular direction.

  6. Exciton dephasing in ZnSe quantum wires

    DEFF Research Database (Denmark)

    Wagner, Hans Peter; Langbein, Wolfgang Werner; Hvam, Jørn Märcher

    1998-01-01

    The homogeneous linewidths of excitons in wet-etched ZnSe quantum wires of lateral sizes down to 23 nm are studied by transient four-wave mixing. The low-density dephasing time is found to increase with decreasing wire width. This is attributed mainly to a reduction of electron-exciton scattering......-one-dimensional system, enhancing the repulsive interaction between excitons due to Pauli blocking....

  7. Mathematical modeling of photovoltaic thermal PV/T system with v-groove collector

    Science.gov (United States)

    Zohri, M.; Fudholi, A.; Ruslan, M. H.; Sopian, K.

    2017-07-01

    The use of v-groove in solar collector has a higher thermal efficiency in references. Dropping the working heat of photovoltaic panel was able to raise the electrical efficiency performance. Electrical and thermal efficiency were produced by photovoltaic thermal (PV/T) system concurrently. Mathematical modeling based on steady-state thermal analysis of PV/T system with v-groove was conducted. With matrix inversion method, the energy balance equations are explained by means of the investigative method. The comparison results show that in the PV/T system with the V-groove collector is higher temperature, thermal and electrical efficiency than other collectors.

  8. Imaging transport of ultracold atoms through a quantum wire

    Science.gov (United States)

    Hausler, Samuel; Lebrat, Martin; Husmann, Dominik; Corman, Laura; Krinner, Sebastian; Nakajima, Shuta; Brantut, Jean-Philippe; Esslinger, Tilman

    2017-04-01

    We report on a scanning gate technique to experimentally image the transport of fermionic lithium atoms through a quantum wire, similar to what is applied to solid state devices. The gate is created with a tightly focused repulsive laser beam whose aberrations are holographically corrected. By scanning its position over the wire and measuring the subsequent variations of conductance, we spatially map the transport at a resolution close to the transverse wave function of atoms inside the channel. The gate extends on the scale of the Fermi wavelength making it sensitive to quantum tunneling. Furthermore, our knowledge of the optical potential allows a direct comparison with an analytical and a numerical model for non-interacting particles. The flexibility offered by programmable holograms make it relatively simple to imprint more complex structures, such as a one-dimensional lattice inside the wire. This opens the path to study metal-insulator physics with strong attractive interactions.

  9. Energy levels in rectangular quantum well wires based on a ...

    Indian Academy of Sciences (India)

    Abstract. The effect of a spatially dependent effective mass on the energy levels in a rectangular quantum wire with finite barrier potential is considered. The heterojunction is modelled by an error function rather than a step function to more accurately model the material transition region at the interface between the two ...

  10. Topological phases and transport properties of screened interacting quantum wires

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hengyi, E-mail: hengyi.xu@njnu.edu.cn [School of Physics and Technology, Nanjing Normal University, Nanjing 210023 (China); Xiong, Ye [School of Physics and Technology, Nanjing Normal University, Nanjing 210023 (China); Wang, Jun [Department of Physics, Southeast University, Nanjing 210096 (China)

    2016-10-14

    We study theoretically the effects of long-range and on-site Coulomb interactions on the topological phases and transport properties of spin–orbit-coupled quasi-one-dimensional quantum wires imposed on a s-wave superconductor. The distributions of the electrostatic potential and charge density are calculated self-consistently within the Hartree approximation. Due to the finite width of the wires and charge repulsion, the potential and density distribute inhomogeneously in the transverse direction and tend to accumulate along the lateral edges where the hard-wall confinement is assumed. This result has profound effects on the topological phases and the differential conductance of the interacting quantum wires and their hybrid junctions with superconductors. Coulomb interactions renormalize the gate voltage and alter the topological phases strongly by enhancing the topological regimes and producing jagged boundaries. Moreover, the multicritical points connecting different topological phases are modified remarkably in striking contrast to the predictions of the two-band model. We further suggest the possible non-magnetic topological phase transitions manipulated externally with the aid of long-range interactions. Finally, the transport properties of normal–superconductor junctions are further examined, in particular, the impacts of Coulomb interactions on the zero-bias peaks related to the Majorana fermions and near zero-energy peaks. - Highlights: • A model of the screened Coulomb interactions in Majorana wires is proposed. • The interacting topological phase diagrams in multiband quantum wires are revealed. • The Majorana fermions in interacting multiband quantum wires are investigated.

  11. Stochastic quantum confinement in nanocrystalline silicon layers: The role of quantum dots, quantum wires and localized states

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez-Porras, A., E-mail: aramirez@fisica.ucr.ac.cr [Centro de Investigación en Ciencia e Ingeniería de Materiales (CICIMA), Universidad de Costa Rica, San Pedro de Montes de Oca 11501 (Costa Rica); Escuela de Física, Universidad de Costa Rica, San Pedro de Montes de Oca 11501 (Costa Rica); García, O. [Escuela de Física, Universidad de Costa Rica, San Pedro de Montes de Oca 11501 (Costa Rica); Escuela de Química, Universidad de Costa Rica, San Pedro de Montes de Oca 11501 (Costa Rica); Vargas, C. [Escuela de Física, Universidad de Costa Rica, San Pedro de Montes de Oca 11501 (Costa Rica); Corrales, A. [Escuela de Física, Universidad de Costa Rica, San Pedro de Montes de Oca 11501 (Costa Rica); Escuela de Química, Universidad de Costa Rica, San Pedro de Montes de Oca 11501 (Costa Rica); Solís, J.D. [Escuela de Física, Universidad de Costa Rica, San Pedro de Montes de Oca 11501 (Costa Rica)

    2015-08-30

    Highlights: • PL spectra of porous silicon samples have been studied using a stochastic model. • This model can deconvolute PL spectra into three components. • Quantum dots, quantum wires and localized states have been identified. • Nanostructure diameters are in the range from 2.2 nm to 4.0 nm. • Contributions from quantum wires are small compared to the others. - Abstract: Nanocrystallites of Silicon have been produced by electrochemical etching of crystal wafers. The obtained samples show photoluminescence in the red band of the visible spectrum when illuminated by ultraviolet light. The photoluminescence spectra can be deconvolved into three components according to a stochastic quantum confinement model: one band coming from Nanocrystalline dots, or quantum dots, one from Nanocrystalline wires, or quantum wires, and one from the presence of localized surface states related to silicon oxide. The results fit well within other published models.

  12. Plasmonic V-groove waveguides with Bragg grating filters via nanoimprint lithography

    DEFF Research Database (Denmark)

    Smith, Cameron L. C.; Desiatov, Boris; Goykmann, Ilya

    2012-01-01

    We demonstrate spectral filtering with state-of-the-art Bragg gratings in plasmonic V-groove waveguides fabricated by wafer scale processing based on nanoimprint lithography. Transmission spectra of the devices having 16 grating periods exhibit spectral rejection of the channel plasmon polaritons...... with effective refractive index values calculated by finite element simulations in COMSOL. The results represent advancement towards the implementation of plasmonic V-grooves with greater functional complexity and mass-production compatibility....

  13. Coupling between a plasmonic V-groove waveguide and single fluorescent bacterial cells

    DEFF Research Database (Denmark)

    Lotan, Oren; Smith, Cameron; David, Jonathan Bar

    2016-01-01

    We experimentally demonstrate coupling of fluorescent light from a single bacterium into a plasmonic V-groove waveguide mode. This result is the first step in the construction of an efficient bioplasmonic chip for diverse sensing applications.......We experimentally demonstrate coupling of fluorescent light from a single bacterium into a plasmonic V-groove waveguide mode. This result is the first step in the construction of an efficient bioplasmonic chip for diverse sensing applications....

  14. Polarization of the photoluminescence of quantum dots incorporated into quantum wires

    Energy Technology Data Exchange (ETDEWEB)

    Platonov, A. V., E-mail: alexei.platonov@mail.ioffe.ru; Kochereshko, V. P.; Kats, V. N.; Cirlin, G. E.; Bouravleuv, A. D.; Avdoshina, D. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Delga, A.; Besombes, L.; Mariette, H. [CEA, INAC, SP2M, and Institut Néel, CEA-CNRS group “Nanophysique et Semiconducteurs” (France)

    2016-12-15

    The photoluminescence spectra of individual quantum dots incorporated into a quantum wire are studied. From the behavior of the spectra in a magnetic field, it is possible to estimate the exciton binding energy in a quantum dot incorporated into a quantum wire. It is found that the exciton photoluminescence signal emitted from a quantum dot along the direction of the nanowire axis is linearly polarized. At the same time, the photoluminescence signal propagating in the direction orthogonal to the nanowire axis is practically unpolarized. The experimentally observed effect is attributed to the nonaxial arrangement of the dot in the wire under conditions of a huge increase in the exciton binding energy due to the effect of the image potential on the exciton.

  15. Scaling behavior in a quantum wire with scatterers

    Energy Technology Data Exchange (ETDEWEB)

    Boese, Daniel; Lischka, Markus; Reichl, L. E.

    2000-12-15

    We study the conductance properties of a straight two-dimensional quantum wire with impurities modeled by s-like scatterers. Their presence can lead to strong interchannel coupling. It was shown that such systems depend sensitively on the number of transverse modes included. Based on a poor man's scaling technique we include the effect of higher modes in a renormalized coupling constant. We therefore show that the low-energy behavior of the wire is dominated by only a few modes, which hence is a way to reduce the necessary computing power. The technique is successfully applied to the case of one and two s-like scatterers.

  16. Helical liquids and Majorana bound states in quantum wires.

    Science.gov (United States)

    Oreg, Yuval; Refael, Gil; von Oppen, Felix

    2010-10-22

    We show that the combination of spin-orbit coupling with a Zeeman field or strong interactions may lead to the formation of a helical electron liquid in single-channel quantum wires, with spin and velocity perfectly correlated. We argue that zero-energy Majorana bound states are formed in various situations when such wires are situated in proximity to a conventional s-wave superconductor. This occurs when the external magnetic field, the superconducting gap, or, most simply, the chemical potential vary along the wire. These Majorana states do not require the presence of a vortex in the system. Experimental consequences of the helical liquid and the Majorana states are also discussed.

  17. Electron energy spectrum in core-shell elliptic quantum wire

    Directory of Open Access Journals (Sweden)

    V.Holovatsky

    2007-01-01

    Full Text Available The electron energy spectrum in core-shell elliptic quantum wire and elliptic semiconductor nanotubes are investigated within the effective mass approximation. The solution of Schrodinger equation based on the Mathieu functions is obtained in elliptic coordinates. The dependencies of the electron size quantization spectrum on the size and shape of the core-shell nanowire and nanotube are calculated. It is shown that the ellipticity of a quantum wire leads to break of degeneration of quasiparticle energy spectrum. The dependences of the energy of odd and even electron states on the ratio between semiaxes are of a nonmonotonous character. The anticrosing effects are observed at the dependencies of electron energy spectrum on the transversal size of the core-shell nanowire.

  18. Enhanced photoelectrochemical performance of bridged ZnO nanorod arrays grown on V-grooved structure.

    Science.gov (United States)

    Wei, Yuefan; Ke, Lin; Leong, Eunice S P; Liu, Hong; Liew, Laura-Lynn; Teng, Jing Hua; Du, Hejun; Sun, Xiao Wei

    2012-09-14

    Bridged ZnO nanorod arrays on a V-grooved Si(100) substrate were used as the photoanode of a photoelectrochemical (PEC) cell for water splitting. Photolithography followed by reactive ion etching was employed to create a V-grooved structure on a Si substrate. ZnO nanorod arrays were grown via a hydrothermal method. The light trapping and PEC properties are greatly enhanced using the bridged ZnO nanorod arrays on a V-grooved Si substrate compared with those on a flat one. Increased short circuit photocurrent density (J(SC), 0.73 mA cm(-2)) and half-life time (1500 s) are achieved. This improved J(SC) and half-life time are 4 times and 10 times, respectively, higher than those of the ZnO nanorod arrays grown on a flat substrate. The overall PEC cell performance improvement for the V-groove grown ZnO array is attributed to the reduced light reflection and enhanced light trapping effect. Moreover, V-groove ZnO showed stronger adhesion between ZnO nanorod arrays and the substrate.

  19. One-dimensional arrangement of nanoparticles utilizing the V-groove and cage shaped proteins

    Science.gov (United States)

    Ban, Takahiko; Uenuma, Mutsunori; Migita, Shinji; Okamoto, Naofumi; Ishikawa, Yasuaki; Uraoka, Yukiharu; Yamashita, Ichiro; Yamamoto, Shin-ichi

    2017-06-01

    The one-dimensional arrangement of nanoparticles (NPs) was performed using a V-groove and ferritins as spherical shell proteins. The V-groove was synthesized by lithography and anisotropic etching of a Si substrate. Ferritin has an outer diameter of 12 nm and an inner diameter of 6 nm, and various inorganic substances can be formed into the cavity. In this study, iron oxide, cobalt oxide, and indium oxide cores were used. The surface potential of ferritin can be changed by genetic modification. Particularly, by using Fer8-K98E, NPs could be arranged one-dimensionally onto the bottom of the V-groove. In addition, we succeeded in selectively forming a one-dimensional array of one layer, two layers, and three layers by changing the protein concentration. This experiment is expected to be applicable to various one-dimensional devices.

  20. Computational Fluid Dynamic Simulation on NACA 0026 Airfoil with V-Groove Riblets

    OpenAIRE

    Ghazali, M.I; Harun, Z; Wan Ghopa, W.A; Abbas, A. A

    2016-01-01

    The aims of this research is to look into the percentage drag reduction on a NACA 0026 airfoil with V-Groove riblets installed around at some locations around its surface. NACA 0026 is a symmetrical airfoil mostly used as turbine blade and aircraft wing. Research on drag reduction by using riblets on the surface was introduced by NASA Langley Research Centre in 1970s. There are many types of riblet designed in this research area such as V groove, segmented blade and continuous sawtooth. This ...

  1. Excitation of fluorescent nanoparticles by channel plasmon polaritons propagating in V-grooves

    DEFF Research Database (Denmark)

    Cuesta, Irene Fernandez; Nielsen, Rasmus Bundgaard; Boltasseva, Alexandra

    2009-01-01

    Recently, it has been proven that light can be squeezed into metallic channels with subwavelength lateral dimensions. Here, we present the study of the propagation of channel plasmon polaritons confined in gold V-grooves, filled with fluorescent particles. In this way, channel plasmon polaritons...... propagating in nonempty V-grooves can be characterized, as the propagation track can be directly visualized in the microscope. We have found that beads with subwavelength diameters act as frequency converters for the propagating channel modes, resulting in larger propagation lengths. For micrometric...

  2. Class D spectral peak in Majorana quantum wires.

    Science.gov (United States)

    Bagrets, Dmitry; Altland, Alexander

    2012-11-30

    Proximity coupled spin-orbit quantum wires purportedly support midgap Majorana states at critical points. We show that, in the presence of disorder, these systems generate a second band center anomaly, which is of different physical origin but shares key characteristics with the Majorana state: it is narrow in width, insensitive to magnetic fields, carries unit spectral weight, and is rigidly tied to the band center. Depending on the parity of the number of subgap quasiparticle states, a Majorana mode does or does not coexist with the impurity peak. The strong "entanglement" between the two phenomena may hinder an unambiguous detection of the Majorana by spectroscopic techniques.

  3. Gain in a quantum wire laser of high uniformity

    OpenAIRE

    Akiyama, Hidefumi; Pfeiffer, Loren N.; Yoshita, Masahiro; Pinczuk, Aron; Littlewood, Peter B.; West, Ken W.; Matthews, Manyalibo J.; Wynn, James

    2002-01-01

    A multi-quantum wire laser operating in the 1-D ground state has been achieved in a very high uniformity structure that shows free exciton emission with unprecedented narrow width and low lasing threshold. Under optical pumping the spontaneous emission evolves from a sharp free exciton peak to a red-shifted broad band. The lasing photon energy occurs about 5 meV below the free exciton. The observed shift excludes free excitons in lasing and our results show that Coulomb interactions in the 1-...

  4. Polariton dispersion of a quantum wire superlattice system

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, K. S. Joseph; Revathy, V. [Department of Physics, Arul Anandar College (Autonomous) Karumathur, Madurai – 625514 (India); Amalanathan, M.; Lenin, S. Maria, E-mail: nathan.amalphysics@gmail.com [Department of physics, Annai Velankanni College, Tholayavattam. Kanyakumari District-629157 (India)

    2015-06-24

    Superlattices have drawn considerable attention in the recent years. In this work, the behaviour of polaritons in a quantum wire superlattice is analysed both at the brillouin zone edge and at centre of the brillouin zone using LiNbO3/ LiTaO3 as an example. The significance of the polariton modes in both the cases are analysed. New modes on the polaritonic gap, where the propagation of electromagnetic wave is forbidden, is obtained in the system as suggested by some recent literature. The effect on nonlinear interactions of phonon polaritons in LiNbO3/ LiTaO3 superlattices is also discussed.

  5. Disorder-induced bound states within an adatom-quantum wire system

    Science.gov (United States)

    Magnetta, Bradley; Ordonez, Gonzalo

    2014-03-01

    Bound states induced by disorder are theoretically observed within a quantum wire and adatom system. The quantum wire is modeled as an array of quantum wells with random energies and exhibits Anderson Localization. By varying the energy of our adatom and adjusting the tunneling strength between the adatom and the quantum wire we observe disorder-induced bound states between the the adatom and its attached point. The characteristics of these disorder-induced bound states are greatly influenced by the site of interest on the quantum wire. Utilizing random quantum wires and disordered superlattices to produce bound states may offer flexibility in fabrication as well as provide grounds for energy transmission in photovoltaics.

  6. Crystal-Phase Quantum Wires: One-Dimensional Heterostructures with Atomically Flat Interfaces.

    Science.gov (United States)

    Corfdir, Pierre; Li, Hong; Marquardt, Oliver; Gao, Guanhui; Molas, Maciej R; Zettler, Johannes K; van Treeck, David; Flissikowski, Timur; Potemski, Marek; Draxl, Claudia; Trampert, Achim; Fernández-Garrido, Sergio; Grahn, Holger T; Brandt, Oliver

    2018-01-10

    In semiconductor quantum-wire heterostructures, interface roughness leads to exciton localization and to a radiative decay rate much smaller than that expected for structures with flat interfaces. Here, we uncover the electronic and optical properties of the one-dimensional extended defects that form at the intersection between stacking faults and inversion domain boundaries in GaN nanowires. We show that they act as crystal-phase quantum wires, a novel one-dimensional quantum system with atomically flat interfaces. These quantum wires efficiently capture excitons whose radiative decay gives rise to an optical doublet at 3.36 eV at 4.2 K. The binding energy of excitons confined in crystal-phase quantum wires is measured to be more than twice larger than that of the bulk. As a result of their unprecedented interface quality, these crystal-phase quantum wires constitute a model system for the study of one-dimensional excitons.

  7. Quantum Phase Transition and Entanglement in Topological Quantum Wires.

    Science.gov (United States)

    Cho, Jaeyoon; Kim, Kun Woo

    2017-06-05

    We investigate the quantum phase transition of the Su-Schrieffer-Heeger (SSH) model by inspecting the two-site entanglements in the ground state. It is shown that the topological phase transition of the SSH model is signified by a nonanalyticity of local entanglement, which becomes discontinuous for finite even system sizes, and that this nonanalyticity has a topological origin. Such a peculiar singularity has a universal nature in one-dimensional topological phase transitions of noninteracting fermions. We make this clearer by pointing out that an analogous quantity in the Kitaev chain exhibiting the identical nonanalyticity is the local electron density. As a byproduct, we show that there exists a different type of phase transition, whereby the pattern of the two-site entanglements undergoes a sudden change. This transition is characterised solely by quantum information theory and does not accompany the closure of the spectral gap. We analyse the scaling behaviours of the entanglement in the vicinities of the transition points.

  8. Electron transport in coupled double quantum wells and wires

    Energy Technology Data Exchange (ETDEWEB)

    Harff, N.E.; Simmons, J.A.; Lyo, S.K. [and others

    1997-04-01

    Due to inter-quantum well tunneling, coupled double quantum wells (DQWs) contain an extra degree of electronic freedom in the growth direction, giving rise to new transport phenomena not found in single electron layers. This report describes work done on coupled DQWs subject to inplane magnetic fields B{sub {parallel}}, and is based on the lead author`s doctoral thesis, successfully defended at Oregon State University on March 4, 1997. First, the conductance of closely coupled DQWs in B{sub {parallel}} is studied. B{sub {parallel}}-induced distortions in the dispersion, the density of states, and the Fermi surface are described both theoretically and experimentally, with particular attention paid to the dispersion anticrossing and resulting partial energy gap. Measurements of giant distortions in the effective mass are found to agree with theoretical calculations. Second, the Landau level spectra of coupled DQWs in tilted magnetic fields is studied. The magnetoresistance oscillations show complex beating as Landau levels from the two Fermi surface components cross the Fermi level. A third set of oscillations resulting from magnetic breakdown is observed. A semiclassical calculation of the Landau level spectra is then performed, and shown to agree exceptionally well with the data. Finally, quantum wires and quantum point contacts formed in DQW structures are investigated. Anticrossings of the one-dimensional DQW dispersion curves are predicted to have interesting transport effects in these devices. Difficulties in sample fabrication have to date prevented experimental verification. However, recently developed techniques to overcome these difficulties are described.

  9. Two-layer synchronized ternary quantum-dot cellular automata wire crossings

    Science.gov (United States)

    2012-01-01

    Quantum-dot cellular automata are an interesting nanoscale computing paradigm. The introduction of the ternary quantum-dot cell enabled ternary computing, and with the recent development of a ternary functionally complete set of elementary logic primitives and the ternary memorizing cell design of complex processing structures is becoming feasible. The specific nature of the ternary quantum-dot cell makes wire crossings one of the most problematic areas of ternary quantum-dot cellular automata circuit design. We hereby present a two-layer wire crossing that uses a specific clocking scheme, which ensures the crossed wires have the same effective delay. PMID:22507371

  10. Comparison studies of infrared photodetectors with a quantum-dot and a quantum-wire base

    Science.gov (United States)

    El Tokhy, M. S.; Mahmoud, I. I.; Konber, H. A.

    2011-12-01

    This paper mainly presents a theoretical analysis for the characteristics of quantum dot infrared photodetectors (QDIPs) and quantum wire infrared photodetectors (QRIPs). The paper introduces a unique mathematical model of solving Poisson's equations with the usage of Lambert W functions for infrared detectors' structures based on quantum effects. Even though QRIPs and QDIPs have been the subject of extensive researches and development during the past decade, it is still essential to implement theoretical models allowing to estimate the ultimate performance of those detectors such as photocurrent and its figure-of-merit detectivity vs. various parameter conditions such as applied voltage, number of quantum wire layers, quantum dot layers, lateral characteristic size, doping density, operation temperature, and structural parameters of the quantum dots (QDs), and quantum wires (QRs). A comparison is made between the computed results of the implemented models and fine agreements are observed. It is concluded from the obtained results that the total detectivity of QDIPs can be significantly lower than that in the QRIPs and main features of the QRIPs such as large gap between the induced photocurrent and dark current of QRIP which allows for overcoming the problems in the QDIPs. This confirms what is evaluated before in the literature. It is evident that by increasing the QD/QR absorption volume in QDIPs/QRIPs as well as by separating the dark current and photocurrents, the specific detectivity can be improved and consequently the devices can operate at higher temperatures. It is an interesting result and it may be benefit to the development of QDIP and QRIP for infrared sensing applications.

  11. Propagation of Channel Plasmons at the Visible Regime in Aluminum V-Groove Waveguides

    DEFF Research Database (Denmark)

    Lotan, Oren; Smith, Cameron; Bar-David, Jonathan

    2016-01-01

    Aluminum plasmonics is emerging as a promising platform in particular for the ultraviolet-blue spectral band. We present the experimental results of propagating channel plasmon-polaritons (CPP) waves in aluminum coated V-shaped waveguides at the short visible wavelength regime. The V-grooves are ......Aluminum plasmonics is emerging as a promising platform in particular for the ultraviolet-blue spectral band. We present the experimental results of propagating channel plasmon-polaritons (CPP) waves in aluminum coated V-shaped waveguides at the short visible wavelength regime. The V......-grooves are fabricated by a process involving UV-photolithography, crystallographic silicon etching, and metal deposition. Polarization measurements of coupling demonstrate a preference to the TM-aligned mode, as predicted in simulations....

  12. Polarization-resolved two-photon luminescence microscopy of V-groove arrays

    DEFF Research Database (Denmark)

    Beermann, J.; Novikov, S. M.; Holmgaard, T.

    2012-01-01

    Using two-photon luminescence (TPL) microscopy and local reflection spectroscopy we investigate electromagnetic field enhancement effects from a mu m-sized composition of 450-nm-deep V-grooves milled by focused ion beam in a thick gold film and assembled to feature, within the same structure...... obtained to evaluation of local field enhancements using TPL microscopy, especially when investigating extended structures exhibiting different radiation channels, are discussed. (C)2011 Optical Society of America...

  13. Electrified Flow in Slender V-Groove Microchannels: Generalized Stability of Steady State Configurations

    Science.gov (United States)

    Markeviciute, Vilda; White, Nicholas; Troian, Sandra

    2017-11-01

    Although spontaneous capillary flow can be an especially rapid process in slender open microchannels resembling V-grooves, enhanced flow control is possible through implementation of electric field distributions which generate opposing electrohydrodynamic pressures along the air/liquid interface to modulate the capillary pressures. Important fundamental work by Romero and Yost (1996) and Weislogel(1996) has elucidated the behavior of Newtonian films in slender V-grooves driven to flow solely by the streamwise change in capillary pressure due to the change in radius of curvature of the circular arc describing the interface of wetting or non-wetting fluids. Here we augment the Romero and Yost model with inclusion of Maxwell stresses for perfectly conducting wetting films and examine which electric field distributions allow formation of steady state film shapes for various inlet and outlet boundary conditions. We investigate the stability of these steady solutions to small perturbations in film thickness using a generalized stability analysis. These results reveal how the ratio of Maxwell to capillary stresses influences the degree of linearized transient growth or decay for thin films confined to flow within an open V-groove. Funding from the 2017 Caltech Summer Undergraduate Research Fellowship Program (Markeviciute) as well as a 2017 NASA Space Technology Research Fellowship (White) is gratefully acknowledged.

  14. Quantum Wires and Waveguides Formed in Graphene by Strain.

    Science.gov (United States)

    Wu, Y; Zhai, D; Pan, C; Cheng, B; Taniguchi, T; Watanabe, K; Sandler, N; Bockrath, M

    2018-01-10

    Confinement of electrons in graphene to make devices has proven to be a challenging task. Electrostatic methods fail because of Klein tunneling, while etching into nanoribbons requires extreme control of edge terminations, and bottom-up approaches are limited in size to a few nanometers. Fortunately, its mechanical flexibility raises the possibility of using strain to alter graphene's properties and create novel straintronic devices. Here, we report transport studies of nanowires created by linearly-shaped strained regions resulting from individual folds formed by layer transfer onto hexagonal boron nitride. Conductance measurements across the folds reveal Coulomb blockade signatures, indicating confined charges within these structures, which act as quantum dots. Along folds, we observe sharp features in traverse resistivity measurements, attributed to an amplification of the dot conductance modulations by a resistance bridge incorporating the device. Our data indicates ballistic transport up to ∼1 μm along the folds. Calculations using the Dirac model including strain are consistent with measured bound state energies and predict the existence of valley-polarized currents. Our results show that graphene folds can act as straintronic quantum wires.

  15. High angular accuracy manufacture method of micro v-grooves based on tool alignment by on-machine measurement.

    Science.gov (United States)

    Zhang, Xiaodong; Jiang, Lili; Zeng, Zhen; Fang, Fengzhou; Liu, Xianlei

    2015-10-19

    Micro v-groove has found wide applications in optical areas as one of the most important structures. However, its performance is significantly affected by its angular geometry accuracy. The diamond cutting has been commonly used as the fabrication method of micro v-groove, but it is still difficult to guarantee the cutting tool angle, which is limited by the measurement accuracy in the manufacture and mounting of the diamond tool. A cutting tool alignment method based on the on-machine measurement is proposed to improve the fabricated quality of the v-groove angle. An on-machine probe is employed to scan the v-groove geometrical deviation precisely. The system errors model, data processing algorithm and tool alignment methods are analyzed in details. Experimental results show that the measurement standard deviation within 0.01° can be achieved. Retro-reflection mirrors are fabricated and measured finally by the proposed method for verification.

  16. Photolithography of thick photoresist coating in anisotropically etched V-grooves for electrically controlled liquid crystal photonic bandgap fiber devices

    DEFF Research Database (Denmark)

    Wei, Lei; Khomtchenko, Elena; Alkeskjold, Thomas Tanggaard

    2009-01-01

    Thick photoresist coating for electrode patterning in anisotropically etched v-grooves is investigated. The photoresist coverage is compared with and without soft baking. Two-step exposure is applied for a complete exposure and minimizing the resolution loss....

  17. Spin-dependent coupling between quantum dots and topological quantum wires

    Science.gov (United States)

    Hoffman, Silas; Chevallier, Denis; Loss, Daniel; Klinovaja, Jelena

    2017-07-01

    Considering Rashba quantum wires with a proximity-induced superconducting gap as physical realizations of Majorana bound states and quantum dots, we calculate the overlap of the Majorana wave functions with the local wave functions on the dot. We determine the spin-dependent tunneling amplitudes between these two localized states and show that we can tune into a fully spin polarized tunneling regime by changing the distance between dot and Majorana bound state. Upon directly applying this to the tunneling model Hamiltonian, we calculate the effective magnetic field on the quantum dot flanked by two Majorana bound states. The direction of the induced magnetic field on the dot depends on the occupation of the nonlocal fermion formed from the two Majorana end states which can be used as a readout for such a Majorana qubit.

  18. Very Efficient Single-Photon Sources Based on Quantum Dots in Photonic Wires

    DEFF Research Database (Denmark)

    Gerard, Jean-Michel; Claudon, Julien; Bleuse, Joel

    2014-01-01

    . By placing a tip-shaped or trumpet-like tapering at the output end of the wire, a highly directional Gaussian far-field emission pattern is obtained. More generally, a photonic wire containing a quantum dot appears as an attractive template to explore and exploit in a solid-state system the unique optical...

  19. Enhanced confinement energy in strained asymmetric T-shaped quantum wires

    DEFF Research Database (Denmark)

    Jensen, Jacob Riis; Hvam, Jørn Märcher; Langbein, W.

    2001-01-01

    A new type of T-shaped quantum wire, based on a sri strained asymmetric structure, has been grown and characterised. A narrow GaAs well is overgrown on an multi quantum well structure consisting of wide InAlGaAs c ells with Al0.3Ga0.7As barriers. Since the lattice constants of the InAlGaAs wells ......-10 meV is found for In molefractions of 10% and 15%, in the multi quantum wells. For an In mole fraction of 20% no quantum wire states are observed, probably due to dislocation formation in the overgrown layers....

  20. Ultra-Low Power Optical Transistor Using a Single Quantum Dot Embedded in a Photonic Wire

    DEFF Research Database (Denmark)

    Nguyen, H.A.; Grange, T.; Malik, N.S.

    2017-01-01

    Using a single InAs quantum dot embedded in a GaAs photonic wire, we realize a giant non-linearity between two optical modes to experimentally demonstrate an all-optical transistor triggered by 10 photons.......Using a single InAs quantum dot embedded in a GaAs photonic wire, we realize a giant non-linearity between two optical modes to experimentally demonstrate an all-optical transistor triggered by 10 photons....

  1. Interaction and Dephasing of Excitons in ZnSe Quantum Wires

    DEFF Research Database (Denmark)

    Wagner, Hans Peter; Langbein, Wolfgang; Hvam, Jørn Märcher

    1999-01-01

    We study the coherent formation of biexcitons in wet-etched ZnSe quantum wires of lateral sizes down to 23 nm by transient degenerate four-wave mixing. We observe an increase of the biexciton binding energy with decreasing wire width reaching 30% energy enhancement in the smallest wire structure...... compared to the mesa structure which is attributed to a quenching of the exciton-exciton scattering efficiency by density dependent measurements. The exciton dephasing is found to increase with decreasing wire width which is assigned to an enhanced repulsive exchange interaction between excitons of equal...

  2. Geometrical dependence of quantum decoherence in circular arenas with side-wires

    Science.gov (United States)

    Xie, Yuantao; Le Priol, Clément; Heremans, Jean J.

    2016-12-01

    Low-temperature quantum phase coherence lengths were experimentally measured in mesoscopic circular arenas fabricated on InGaAs quantum wells. The arenas are connected to wide sample regions by short side-wires, to investigate the effects of geometry in comparison to intrinsic materials properties on quantum decoherence. Universal conductance fluctuations were used to quantify the phase coherence lengths as a function of temperature and geometry. The experimental data show a dependence of phase coherence lengths on side-wire length and width-to-length ratio, which is accounted for by the competing effects of decoherence by coupling to the classical environment and Nyquist decoherence in ergodic wires. The observed decay of phase coherence lengths with the increasing temperature is consistent with expectations. The work demonstrates that geometrical effects influence the measured mesoscopic quantum decoherence.

  3. GaAs Solar Cells on V-Grooved Silicon via Selective Area Growth: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Emily L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jain, Nikhil [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tamboli, Adele C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Vaisman, Michelle [Yale University; Li, Qiang [Hong Kong University of Science and Technology; Lau, Kei May [Hong Kong University of Science and Technology

    2017-08-31

    Interest in integrating III-Vs onto Si has recently resurged as a promising pathway towards high-efficiency, low-cost tandem photovoltaics. Here, we present a single junction GaAs solar cell grown monolithically on polished Si (001) substrates using V-grooves, selective area growth, and aspect ratio trapping to mitigate defect formation without the use of expensive, thick graded buffers. The GaAs is free of antiphase domains and maintains a relatively low TDD of 4x107 cm-2, despite the lack of a graded buffer. This 6.25 percent-efficient demonstration solar cell shows promise for further improvements to III-V/Si tandems to enable cost-competitive photovoltaics.

  4. The scaling of the effective band gaps in indium-arsenide quantum dots and wires.

    Science.gov (United States)

    Wang, Fudong; Yu, Heng; Jeong, Sohee; Pietryga, Jeffrey M; Hollingsworth, Jennifer A; Gibbons, Patrick C; Buhro, William E

    2008-09-23

    Colloidal InAs quantum wires having diameters in the range of 5-57 nm and narrow diameter distributions are grown from Bi nanoparticles by the solution-liquid-solid (SLS) mechanism. The diameter dependence of the effective band gaps (DeltaE(g)s) in the wires is determined from photoluminescence spectra and compared to the experimental results for InAs quantum dots and rods and to the predictions of various theoretical models. The DeltaE(g) values for InAs quantum dots and wires are found to scale linearly with inverse diameter (d(-1)), whereas the simplest confinement models predict that DeltaE(g) should scale with inverse-square diameter (d(-2)). The difference in the observed and predicted scaling dimension is attributed to conduction-band nonparabolicity induced by strong valence-band-conduction-band coupling in the narrow-gap InAs semiconductor.

  5. Quantum interference and manipulation of entanglement in silicon wire waveguide quantum circuits

    NARCIS (Netherlands)

    Bonneau, D.; Engin, E.; Dorenbos, S.N.; Zwiller, V.

    2012-01-01

    Integrated quantum photonic waveguide circuits are a promising approach to realizing future photonic quantum technologies. Here, we present an integrated photonic quantum technology platform utilizing the silicon-oninsulator material system, where quantum interference and the manipulation of quantum

  6. Beam and phase distributions of a terahertz quantum cascade wire laser

    NARCIS (Netherlands)

    Cui, M.; Hovenier, J.N.; Ren, Y.; Vercruyssen, N.; Gao, J.R.; Kao, T.Y.; Hu, Q.; Reno, J.L.

    2013-01-01

    We report on both measurements and simulations of the beam profile and wavefront of a single-mode, 3.5?THz quantum cascade wire laser, incorporating a lateral corrugated metal-metal waveguide, 3rd-order distributed feedback grating. The intrinsic wavefront was measured by using a Hartmann wavefront

  7. Electron-phonon interaction in a semiconductor quantum wire embedded into the semiconductor medium

    CERN Document Server

    Zharkoj, V P

    2002-01-01

    The renormalization of electron ground state energy due to the different types of interaction with confined (L) and interface (I) phonons in a semiconductor cylindrical quantum wire (QW) embedded into the semiconductor medium by the example of a HgS/CdS nanosystem.

  8. Transient four-wave mixing in T-shaped GaAs quantum wires

    DEFF Research Database (Denmark)

    Langbein, Wolfgang Werner; Gislason, Hannes; Hvam, Jørn Märcher

    1999-01-01

    The binding energy of excitons and biexcitons and the exciton dephasing in T-shaped GaAs quantum wires is investigated by transient four-wave mixing. The T-shaped structure is fabricated by cleaved-edge overgrowth, and its geometry is engineered to optimize the one-dimensional confinement...

  9. Spin-Filtering Transport in Double Parallel Quantum Wires on a Graphene Sheet

    Science.gov (United States)

    Yang, Fu-Bin; Cheng, Yan; Liu, Fu-Ti; Chen, Xiang-Rong; Cai, Ling-Cang

    2015-03-01

    We theoretically investigate the spin filtering transport of double parallel quantum wires (QWs) side-coupled to a graphene sheet and sandwiched between two ferromagnetic (FM) leads. The dependences of the wire-graphene coupling strength, wire-wire coupling strength, as well as the spin polarization of the ferromagnetic leads are studied. It is found that the wire-graphene coupling strength tends to reduce the current and the wire-wire coupling strength can first reinforce and then decrease the current. The spin polarization strength has an enhanced (identical) effect on the current under the parallel (anti-parallel) alignment of the FM leads, which gives rise to an obvious spin-filter and tunnel magnetoresistance (TMR) effect. Our results suggest that such a theoretical model can stimulate some experimental investigations about the spin-filter devices. Supported by the National Natural Science Foundation of China under Grant Nos. 11174214, 11204192, the NSAF Joint Fund Jointly set up by the National Natural Science Foundation of China and the Chinese Academy of Engineering Physics under Grant Nos. U1230201 and U1430117

  10. Gate-Defined Wires in HgTe Quantum Wells: From Majorana Fermions to Spintronics

    Directory of Open Access Journals (Sweden)

    Johannes Reuther

    2013-08-01

    Full Text Available We introduce a promising new platform for Majorana zero modes and various spintronics applications based on gate-defined wires in HgTe quantum wells. Because of the Dirac-like band structure for HgTe, the physics of such systems differs markedly from that of conventional quantum wires. Most strikingly, we show that the subband parameters for gate-defined HgTe wires exhibit exquisite tunability: Modest gate voltage variation allows one to modulate the Rashba spin-orbit energies from zero up to about 30 K, and the effective g factors from zero up to giant values exceeding 600. The large achievable spin-orbit coupling and g factors together allow one to access Majorana modes in this setting at exceptionally low magnetic fields while maintaining robustness against disorder. As an additional benefit, gate-defined wires (in HgTe or other settings should greatly facilitate the fabrication of networks for refined transport experiments used to detect Majoranas, as well as the realization of non-Abelian statistics and quantum information devices.

  11. Topological quantum wires with balanced gain and loss

    Science.gov (United States)

    Menke, Henri; Hirschmann, Moritz M.

    2017-05-01

    We study a one-dimensional topological superconductor, the Kitaev chain, under the influence of a non-Hermitian but PT -symmetric potential. This potential introduces gain and loss in the system in equal parts. We show that the stability of the topological phase is influenced by the gain/loss strength and explicitly derive the bulk topological invariant in a bipartite lattice as well as compute the corresponding phase diagram using analytical and numerical methods. Furthermore, we find that the edge state is exponentially localized near the ends of the wire despite the presence of gain and loss of probability amplitude in that region.

  12. Efficient Terahertz Plasmonic Absorbers with V-Grooves Using Highly Doped Silicon Substrate and Simple Wet-Etching Techniques

    Science.gov (United States)

    Zhai, Mengfei; Yuan, Wei; Han, Zhanghua

    2017-12-01

    We experimentally demonstrate that at terahertz frequencies perfect plasmonic absorbers made from a 3D V-groove array in a highly doped silicon wafer can be easily realized using simple wet-etching process. The surface plasmon modes can be excited by the V-groove array and get decayed when they propagate along the silicon surface and enter the grooves, inducing a broadband near-zero dip in the reflection spectra. The reflection spectrum of the fabricated absorber is characterized using a terahertz time-domain spectroscopy system, and the experimental results are in good agreement with numerical simulations. The high performance including high absorptivity and large bandwidth together with the easy fabrication processes presented in this paper make this plasmonic absorber promising for a wide range of practical applications in terahertz regime.

  13. Calculating modes of quantum wire systems using a finite difference technique

    Directory of Open Access Journals (Sweden)

    T Mardani

    2013-03-01

    Full Text Available  In this paper, the Schrodinger equation for a quantum wire is solved using a finite difference approach. A new aspect in this work is plotting wave function on cross section of rectangular cross-sectional wire in two dimensions, periodically. It is found that the correct eigen energies occur when wave functions have a complete symmetry. If the value of eigen energy has a small increase or decrease in neighborhood of the correct energy the symmetry will be destroyed and aperturbation value at the first of wave function will be observed. In addition, the demand on computer memory varies linearly with the size of the system under investigation.

  14. Coherent control of lattice deformations in quantum wires by optical self-trapping

    OpenAIRE

    Katkov, M. V.; Piermarocchi, C.

    2004-01-01

    We investigate theoretically a semiconductor quantum wire under the effect of an intense off-resonant cw laser. We show that in the regime of strong exciton-phonon coupling the light-dressed ground state of the wire reveals symmetry-breaking features, leading to local lattice deformations. Due to the off-resonant nature of the excitation, the deformations are reversible and controllable by the intensity and frequency of the laser. We calculate the light-induced strain forces on the lattice in...

  15. Effective field theory for the quantum electrodynamics of a graphene wire

    Science.gov (United States)

    Faccioli, P.; Lipparini, E.

    2009-07-01

    We study the low-energy quantum electrodynamics of electrons and holes in a thin graphene wire. We develop an effective field theory (EFT) based on an expansion in p/pT , where pT is the typical momentum of electrons and holes in the transverse direction, while p are the momenta in the longitudinal direction. We show that, to the lowest order in (p/pT) , our EFT theory is formally equivalent to the exactly solvable Schwinger model. By exploiting such an analogy, we find that the ground state of the quantum wire contains a condensate of electron-hole pairs. The excitation spectrum is saturated by electron-hole collective bound states, and we calculate the dispersion law of such modes. We also compute the dc conductivity per unit length at zero chemical potential and find gs(e2)/(h) , where gs=4 is the degeneracy factor.

  16. The influence of resonance IR laser radiation on magnetoabsorption in quantum wires

    Science.gov (United States)

    Sinyavskii, E. P.; Karapetyan, S. A.; Kostyukevich, N. S.

    2017-04-01

    The coefficient of interband absorption of a weak electromagnetic wave by quantum wires in a transverse magnetic field and an intense laser radiation field is calculated. It is shown that, if the laser radiation frequency is equal either to the size quantization frequency (dimensional infrared resonance) or to a hybrid frequency (magnetoinfrared resonance), laser illumination can determine the shape of absorption oscillations. In particular, it is shown that the second magnetoabsorption peak is split into two peaks, the half-widths of which and the distance between which depend on the intensity of resonance laser radiation. The influence of the polarization of IR radiation on the interband absorption in quantum wires is discussed. The dynamics of the frequency dependence of the optical absorption coefficient with increasing intensity of resonance laser radiation is studied.

  17. Nuclear Quantum Effects in H(+) and OH(-) Diffusion along Confined Water Wires.

    Science.gov (United States)

    Rossi, Mariana; Ceriotti, Michele; Manolopoulos, David E

    2016-08-04

    The diffusion of protons and hydroxide ions along water wires provides an efficient mechanism for charge transport that is exploited by biological membrane channels and shows promise for technological applications such as fuel cells. However, what is lacking for a better control and design of these systems is a thorough theoretical understanding of the diffusion process at the atomic scale. Here we focus on two aspects of this process that are often disregarded because of their high computational cost: the use of first-principles potential energy surfaces and the treatment of the nuclei as quantum particles. We consider proton and hydroxide ions in finite water wires using density functional theory augmented with an apolar cylindrical confining potential. We employ machine learning techniques to identify the charged species, thus obtaining an agnostic definition that takes explicitly into account the delocalization of the charge in the Grotthus-like mechanism. We include nuclear quantum effects (NQEs) through the thermostated ring polymer molecular dynamics method and model finite system size effects by considering Langevin dynamics on the potential of mean force of the charged species, allowing us to extract the same "universal" diffusion coefficient from simulations with different wire sizes. In the classical case, diffusion coefficients depend significantly on the potential energy surface, in particular on how dispersion forces modulate water-water distances. NQEs, however, make the diffusion less sensitive to the underlying potential and geometry of the wire.

  18. Excitons, Biexcitons and Dephasing in GaAs T-shaped quantum wires

    DEFF Research Database (Denmark)

    Langbein, Wolfgang; Gislason, Hannes; Hvam, Jørn Märcher

    2000-01-01

    . In this wire of 6.6x24 nm2 size we find a one-dimensional confinement of more than 20meV, an inhomogeneous broadening of only 3.4 meV. The measured exciton binding energy of 12 meV is in good agreement with numerical calculations. The biexciton binding energy of 2.0 meV is less than in comparable quantum well...

  19. Effect of electron-phonon interaction on the impurity binding energy in a quantum wire

    OpenAIRE

    Chen, Yueh-Nan; Chuu, Der-San; Lin, Yuh-Kae

    2003-01-01

    The effect of electron-optical phonon interaction on the hydrogenic impurity binding energy in a cylindrical quantum wire is studied. By using Landau and Pekar variational method, the hamiltonian is separated into two parts which contain phonon variable and electron variable respectively. A perturbative-variational technique is then employed to construct the trial wavefunction for the electron part. The effect of confined electron-optical phonon interaction on the binding energies of the grou...

  20. Strong photo-absorption by a single quantum wire in waveguide-transmission spectroscopy

    OpenAIRE

    Takahashi, Yasushi; Hayamizu, Yuhei; Itoh, Hirotake; Yoshita, Masahiro; Akiyama, Hidefumi; Pfeiffer, Loren N.; West, Ken W.

    2005-01-01

    We measured the absorption spectrum of a single T-shaped, 14x6 nm lateral-sized quantum wire embedded in an optical waveguide using waveguide-transmission spectroscopy at 5 K. In spite of its small volume, the one-dimensional-exciton ground state shows a large absorption coefficient of 80 /cm, or a 98 % absorption probability for a single pass of the 500-um-long waveguide.

  1. Imaging of emission patterns in a T-shaped quantum wire laser

    OpenAIRE

    Takahashi, Yasushi; Watanabe, Shinichi; Yoshita, Masahiro; Itoh, Hirotake; Hayamizu, Yuhei; Akiyama, Hidefumi; Pfeiffer, Loren N.; West, Ken W.

    2003-01-01

    Spatially and spectrally resolved microscopic images of spontaneous and stimulated emissions are imaged at the mirror facets of a GaAs T-shaped quantum wire laser with high uniformity. Laser emission from the one-dimensional ground state reveals a circular image located at the core of a T-shaped optical waveguide but significantly smaller in area than the low power spontaneous emission from the same waveguide. These images unambiguously allow assignment of all spontaneous and laser emissions ...

  2. Transverse Stark effect in the optical absorption in a square semiconducting quantum wire

    Science.gov (United States)

    Sheng, Wang; Yun, Kang; Chunjie, Han

    2013-10-01

    The ground and few excited states of the electrons confined in a square GaAs quantum wire (QW) subjected to an external transverse electric field are investigated using the finite difference method within the effective-mass approximation. When the transverse electric field is applied along a side of the square quantum wire, the calculation of the eigenstates of the quantum wire has an exactly solvable problem whose solutions involve the linear combinations of two independent Airy functions. Compared with the exact analytical results using Airy functions, the results obtained by the use of the finite difference method in terms of the eigenstates of the particle in the QW are in excellent agreement. Subsequently, it is considered that the eigenstates of the particle depend on the orientations of the electric field with respect to the center axis of the QW. It is interesting that the peak value of the energy is found for the field directed along the diagonal in the QW, which can lead to a large energy shift. Meanwhile, dependence of the optical absorption phenomenon in the square QW on the optical field and applied electric field is investigated. It is shown that the optical absorption spectrum depends highly upon the polarization of the optical field and the applied electric field intensities and orientations.

  3. Interaction effects in a microscopic quantum wire model with strong spin-orbit interaction

    Science.gov (United States)

    Winkler, G. W.; Ganahl, M.; Schuricht, D.; Evertz, H. G.; Andergassen, S.

    2017-06-01

    We investigate the effect of strong interactions on the spectral properties of quantum wires with strong Rashba spin-orbit (SO) interaction in a magnetic field, using a combination of matrix product state and bosonization techniques. Quantum wires with strong Rashba SO interaction and magnetic field exhibit a partial gap in one-half of the conducting modes. Such systems have attracted wide-spread experimental and theoretical attention due to their unusual physical properties, among which are spin-dependent transport, or a topological superconducting phase when under the proximity effect of an s-wave superconductor. As a microscopic model for the quantum wire we study an extended Hubbard model with SO interaction and Zeeman field. We obtain spin resolved spectral densities from the real-time evolution of excitations, and calculate the phase diagram. We find that interactions increase the pseudo gap at k = 0 and thus also enhance the Majorana-supporting phase and stabilize the helical spin order. Furthermore, we calculate the optical conductivity and compare it with the low energy spiral Luttinger liquid result, obtained from field theoretical calculations. With interactions, the optical conductivity is dominated by an excotic excitation of a bound soliton-antisoliton pair known as a breather state. We visualize the oscillating motion of the breather state, which could provide the route to their experimental detection in e.g. cold atom experiments.

  4. The fabrication and characterisation of quantum dots, wires and wire net works

    CERN Document Server

    Zhang, Q

    1996-01-01

    luminescent materials probably involves pi bonded carbon. The size distributions of both kinds of the nanoclusters obtained by TEM suggest that a quantum-confined size effect can also apply to the blue PL. The strong blue emission is related with the crystallisation of the nanodots by annealing. The PL excitation dependence is explained by an increase in the conduction band density of states deep in the band, and the formation of a band tail. The work in this thesis includes two aspects as described below: 1. Freshly produced red, yellow and green emitting porous Si have been fabricated and studied by NEXAFS and EXAFS. The emission peaks are at 690, 580 and 520 nm, which almost covers the fall visible range that direct anodization can achieve. The correlation between the co-ordination numbers of the first, second and third Si neighbour shells from Fourier transform fitting of EXAFS and both emission peak energies and optical bandgaps estimated by PLE (photoluminescence excitation dependence) suggests that the...

  5. Spin-orbit interaction in quantum dots and quantum wires of correlated electrons - a way to spintronics?

    Energy Technology Data Exchange (ETDEWEB)

    Birkholz, Jens Eiko

    2008-10-06

    We study the influence of the spin-orbit interaction on the electronic transport through quantum dots and quantum wires of correlated electrons. Starting with a one-dimensional infinite continuum model without Coulomb interaction, we analyze the interplay of the spin-orbit interaction, an external magnetic field, and an external potential leading to currents with significant spin-polarization in appropriate parameter regimes. Since lattice models are known to often be superior to continuum models in describing the experimental situation of low-dimensional mesoscopic systems, we construct a lattice model which exhibits the same low-energy physics in terms of energy dispersion and spin expectation values. Confining the lattice to finite length and connecting it to two semi-infinite noninteracting Fermi liquid leads, we calculate the zero temperature linear conductance using the Landauer-Bttiker formalism and show that spin-polarization effects also evolve for the lattice model by adding an adequate potential structure and can be controlled by tuning the overall chemical potential of the system (quantum wire and leads). Next, we allow for a finite Coulomb interaction and use the functional renormalization group (fRG) method to capture correlation effects induced by the Coulomb interaction. The interacting system is thereby transformed into a noninteracting system with renormalized system parameters. For short wires ({proportional_to}100 lattice sites), we show that the energy regime in which spin polarization is found is strongly affected by the Coulomb interaction. For long wires (>1000 lattice sites), we find the power-law suppression of the total linear conductance on low energy scales typical for inhomogeneous Luttinger liquids while the degree of spin polarization stays constant. Considering quantum dots which consist of two lattice sites, we observe the well-known Kondo effect and analyze, how the Kondo temperature is affected by the spin-orbit interaction

  6. Symmetry-induced quantum interference effects in metalloporphyrin wires.

    Science.gov (United States)

    Ferradás, R; García-Suárez, V M; Ferrer, J

    2013-08-14

    We calculate the electronic and transport properties of a series of metalloporphyrin molecules sandwiched between gold electrodes using a combination of density functional theory and scattering theory. The impact of strong correlations at the central metallic atom is gauged by comparing our results obtained using conventional DFT and DFT + U approaches. The zero- and finite-bias transport properties may or may not show spin-filtering behavior, depending on the nature of the d state closest to the Fermi energy. The type of d state depends on the metallic atom and gives rise to interference effects that produce different Fano features. The inclusion of the U term opens a gap between the d states and changes the conductance and spin-filtering behavior qualitatively in some of the molecules. We explain the origin of the quantum interference effects found as due to the symmetry-dependent coupling between the d states and other molecular orbitals and propose the use of these systems as nanoscale chemical sensors. We also demonstrate that an adequate treatment of strong correlations is really necessary to correctly describe the transport properties of metalloporphyrins and similar molecular magnets.

  7. Nonequilibrium transport through quantum-wire junctions and boundary defects for free massless bosonic fields

    Directory of Open Access Journals (Sweden)

    Krzysztof Gawȩdki

    2015-07-01

    Full Text Available We consider a model of quantum-wire junctions where the latter are described by conformal-invariant boundary conditions of the simplest type in the multicomponent compactified massless scalar free field theory representing the bosonized Luttinger liquids in the bulk of wires. The boundary conditions result in the scattering of charges across the junction with nontrivial reflection and transmission amplitudes. The equilibrium state of such a system, corresponding to inverse temperature β and electric potential V, is explicitly constructed both for finite and for semi-infinite wires. In the latter case, a stationary nonequilibrium state describing the wires kept at different temperatures and potentials may be also constructed. The main result of the present paper is the calculation of the full counting statistics (FCS of the charge and energy transfers through the junction in a nonequilibrium situation. Explicit expressions are worked out for the generating function of FCS and its large-deviations asymptotics. For the purely transmitting case they coincide with those obtained in the literature, but numerous cases of junctions with transmission and reflection are also covered. The large deviations rate function of FCS for charge and energy transfers is shown to satisfy the fluctuation relations and the expressions for FCS obtained here are compared with the Levitov–Lesovik formulae.

  8. Binding energy of a hydrogenic impurity in a coaxial quantum wire with an insulator layer

    Science.gov (United States)

    Kes, H.; Bilekkaya, A.; Aktas, S.; Okan, S. E.

    2017-11-01

    The electronic properties of a coaxial cylindrical quantum well-barrier system constituted about an central insulating wire were determined under an external electric field. The model wire, inside to outside, was considered to be layered as AlAs / GaAs / Alx1 Ga1 -x1 As / GaAs / Alx2 Ga1 -x2 As. Within the framework of the effective mass-approximation, the binding energy of a hydrogenic impurity is calculated by using the combination of the fourth-order Runge-Kutta method and variational approaches. The binding energy exhibits sharp changes depending on the impurity position and the geometrical parameters of the structure such as the well widths of the GaAs wires and the height and thickness of the barrier constituted by Alx1 Ga1 -x1 As . The binding energy of the electron was found to be independent from the impurity position for the specific widths of the well wires. Also, the barrier properties appeared as very effective parameters in controlling the probability distribution of the electron.

  9. Effects of photon field on heat transport through a quantum wire attached to leads

    Science.gov (United States)

    Abdullah, Nzar Rauf; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar

    2018-01-01

    We theoretically investigate photo-thermoelectric transport through a quantum wire in a photon cavity coupled to electron reservoirs with different temperatures. Our approach, based on a quantum master equation, allows us to investigate the influence of a quantized photon field on the heat current and thermoelectric transport in the system. We find that the heat current through the quantum wire is influenced by the photon field resulting in a negative heat current in certain cases. The characteristics of the transport are studied by tuning the ratio, ħωγ /kB ΔT, between the photon energy, ħωγ, and the thermal energy, kB ΔT. The thermoelectric transport is enhanced by the cavity photons when kB ΔT > ħωγ. By contrast, if kB ΔT < ħωγ, the photon field is dominant and a suppression in the thermoelectric transport can be found in the case when the cavity-photon field is close to a resonance with the two lowest one-electron states in the system. Our approach points to a new technique to amplify thermoelectric current in nano-devices.

  10. Quantum Wells, Wires and Dots Theoretical and Computational Physics of Semiconductor Nanostructures

    CERN Document Server

    Harrison, Paul

    2011-01-01

    Quantum Wells, Wires and Dots, 3rd Edition is aimed at providing all the essential information, both theoretical and computational, in order that the reader can, starting from essentially nothing, understand how the electronic, optical and transport properties of semiconductor heterostructures are calculated. Completely revised and updated, this text is designed to lead the reader through a series of simple theoretical and computational implementations, and slowly build from solid foundations, to a level where the reader can begin to initiate theoretical investigations or explanations of their

  11. Majorana fermions in equilibrium and in driven cold-atom quantum wires.

    Science.gov (United States)

    Jiang, Liang; Kitagawa, Takuya; Alicea, Jason; Akhmerov, A R; Pekker, David; Refael, Gil; Cirac, J Ignacio; Demler, Eugene; Lukin, Mikhail D; Zoller, Peter

    2011-06-03

    We introduce a new approach to create and detect Majorana fermions using optically trapped 1D fermionic atoms. In our proposed setup, two internal states of the atoms couple via an optical Raman transition-simultaneously inducing an effective spin-orbit interaction and magnetic field-while a background molecular BEC cloud generates s-wave pairing for the atoms. The resulting cold-atom quantum wire supports Majorana fermions at phase boundaries between topologically trivial and nontrivial regions, as well as "Floquet Majorana fermions" when the system is periodically driven. We analyze experimental parameters, detection schemes, and various imperfections.

  12. A Model System for Dimensional Competition in Nanostructures: A Quantum Wire on a Surface

    Directory of Open Access Journals (Sweden)

    Dick Rainer

    2008-01-01

    Full Text Available AbstractThe retarded Green’s function (E−H + iε−1is given for a dimensionally hybrid Hamiltonian which interpolates between one and two dimensions. This is used as a model for dimensional competition in propagation effects in the presence of one-dimensional subsystems on a surface. The presence of a quantum wire generates additional exponential terms in the Green’s function. The result shows how the location of the one-dimensional subsystem affects propagation of particles.

  13. Simulations of quantum transport in nanoscale systems: application to atomic gold and silver wires

    DEFF Research Database (Denmark)

    Mozos, J.L.; Ordejon, P.; Brandbyge, Mads

    2002-01-01

    's function techniques are used to calculate the quantum conductance. Here we apply the method to the study of the electronic transport in wires of gold and silver with atomic thickness. We show the results of our calculations, and compare with some of the abundant experimental data on these systems.......We present a first-principles method for studying the electronic transport through nanoscale atomic systems under non-equilibrium conditions. The method is based on density functional theory, and allows the calculation of the response of the system to an applied finite potential difference...

  14. Quantum wells, wires and dots theoretical and computational physics of semiconductor nanostructures

    CERN Document Server

    Harrison, Paul

    2016-01-01

    Quantum Wells, Wires and Dots provides all the essential information, both theoretical and computational, to develop an understanding of the electronic, optical and transport properties of these semiconductor nanostructures. The book will lead the reader through comprehensive explanations and mathematical derivations to the point where they can design semiconductor nanostructures with the required electronic and optical properties for exploitation in these technologies. This fully revised and updated 4th edition features new sections that incorporate modern techniques and extensive new material including: - Properties of non-parabolic energy bands - Matrix solutions of the Poisson and Schrodinger equations - Critical thickness of strained materials - Carrier scattering by interface roughness, alloy disorder and impurities - Density matrix transport modelling -Thermal modelling Written by well-known authors in the field of semiconductor nanostructures and quantum optoelectronics, this user-friendly guide is pr...

  15. External electric field effect on exciton binding energy in InGaAsP/InP cylindrical quantum wires

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hailong, E-mail: hlwang@mail.qfnu.edu.cn [College of Physics and Engineering, Qufu Normal University, Qufu 273165 (China); Wang, Wenjuan [College of Physics and Engineering, Qufu Normal University, Qufu 273165 (China); Gong, Qian; Wang, Shumin [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

    2016-12-15

    Exciton binding energies in InGaAsP/InP cylindrical quantum wires are calculated through variational method under the framework of effective-mass envelope-function approximation. It is shown that the variation of exciton binding energy is highly dependent on radius of the wire, material composition and external electric field. Exciton binding energy is a non-monotonic function of wire radius. It increases until it reaches a maximum, and then decreases as the wire radius decreases. With the increase of In composition, the wire radius need increase to reach the maximum value of exciton binding energy. It is also found that the external electric field has little effect on exciton binding energy. However, the excitonic effect will be destroyed when external electric field is large enough. In addition, the Stark shift of exciton binding energy is also calculated.

  16. Wire-shaped quantum dots-sensitized solar cells based on nanosheets and nanowires.

    Science.gov (United States)

    Chen, Haining; Zhu, Liqun; Wang, Meng; Liu, Huicong; Li, Weiping

    2011-11-25

    Wire-shaped quantum dots-sensitized solar cells (WS-QDSCs) based on nanosheets and nanowires were fabricated and investigated for this paper. The nanosheets grown on stainless steel (SS) wire by electrodeposition were mainly composed of Zn₅(OH)₈Cl₂·H₂O and most of the Zn₅(OH)₈Cl₂·H₂O was converted to ZnO by post-treatment, and ZnO nanowires were directly grown on SS wire by the hydrothermal method. CdS QDs were deposited on nanosheets and nanowires by successive ionic layer adsorption and reaction method. The results of photoelectrochemical performance indicated that WS-QDSCs showed a similar conversion efficiency in polysulfide and Na₂SO₄ electrolytes, while the WS-QDSCs based on the Cu2S counter electrode achieved much higher performance than those based on SS and Cu counter electrodes. By optimizing electrodeposition duration, the WS-QDSCs based on nanosheets presented the highest conversion efficiency of 0.60% for the duration of 20 min. Performance comparison indicated that the WS-QDSC based on nanosheets showed very superior performance to that based on the nanowires with similar film thickness.

  17. Inelastic electron and Raman scattering from the collective excitations in quantum wires: Zero magnetic field

    Directory of Open Access Journals (Sweden)

    Manvir S. Kushwaha

    2013-04-01

    Full Text Available The nanofabrication technology has taught us that an m-dimensional confining potential imposed upon an n-dimensional electron gas paves the way to a quasi-(n-m-dimensional electron gas, with m ⩽ n and 1 ⩽ n, m ⩽ 3. This is the road to the (semiconducting quasi-n dimensional electron gas systems we have been happily traversing on now for almost two decades. Achieving quasi-one dimensional electron gas (Q-1DEG [or quantum wire(s for more practical purposes] led us to some mixed moments in this journey: while the reduced phase space for the scattering led us believe in the route to the faster electron devices, the proximity to the 1D systems left us in the dilemma of describing it as a Fermi liquid or as a Luttinger liquid. No one had ever suspected the potential of the former, but it took quite a while for some to convince the others on the latter. A realistic Q-1DEG system at the low temperatures is best describable as a Fermi liquid rather than as a Luttinger liquid. In the language of condensed matter physics, a critical scrutiny of Q-1DEG systems has provided us with a host of exotic (electronic, optical, and transport phenomena unseen in their higher- or lower-dimensional counterparts. This has motivated us to undertake a systematic investigation of the inelastic electron scattering (IES and the inelastic light scattering (ILS from the elementary electronic excitations in quantum wires. We begin with the Kubo's correlation functions to derive the generalized dielectric function, the inverse dielectric function, and the Dyson equation for the dynamic screened potential in the framework of Bohm-Pines’ random-phase approximation. These fundamental tools then lead us to develop methodically the theory of IES and ILS for the Q-1DEG systems. As an application of the general formal results, which know no bounds regarding the subband occupancy, we compute the density of states, the Fermi energy, the full excitation spectrum [comprised of

  18. Spectroscopy of shallow InAs/InP quantum wire nanostructures.

    Science.gov (United States)

    Mazur, Yu I; Dorogan, V G; Bierwagen, O; Tarasov, G G; DeCuir, E A; Noda, S; Zhuchenko, Z Ya; Manasreh, M O; Masselink, W T; Salamo, G J

    2009-02-11

    A comprehensive investigation of the optical properties of InAs/InP(001) quantum wires (QWrs) and their parent quantum well system formed by the deposition of 4 ML (monolayers) of InAs on InP is carried out by means of temperature dependent photoluminescence (PL) and Fourier transform infrared spectroscopy. Unusual two-branch switching of the excitonic PL band maxima is revealed in the temperature dependence for both wires and wells. This is interpreted in terms of the thermal activation of excitonic ground states of the confined nanostructures. Strong modification of the absorbance line shape leading to the appearance of flat spectral regions in the room temperature spectrum of a QWr sample is interpreted in terms of thermally induced change of the dimensionality: from 1D to anisotropic 2D. This change of dimensionality is detected also in the polarized absorbance measurements through the disappearance or significant reduction of the polarization anisotropy in the regions of the hh1-e1 (hh: heavy hole; e: electron) and lh1-e1 (lh: light hole) transitions in QWrs.

  19. Charge carrier relaxation in InGaAs-GaAs quantum wire modulation-doped heterostructures

    Science.gov (United States)

    Kondratenko, S. V.; Iliash, S. A.; Mazur, Yu I.; Kunets, V. P.; Benamara, M.; Salamo, G. J.

    2017-09-01

    The time dependencies of the carrier relaxation in modulation-doped InGaAs-GaAs low-dimensional structures with quantum wires have been studied as functions of temperature and light excitation levels. The photoconductivity (PC) relaxation follows a stretched exponent with decay constant, which depends on the morphology of InGaAs epitaxial layers, presence of deep traps, and energy disorder due to inhomogeneous distribution of size and composition. A hopping model, where electron tunnels between bands of localized states, gives appropriate interpretation for temperature-independent PC decay across the temperature range 150-290 K. At low temperatures (T InGaAs quantum wires (QWRs), sub-bands of two-dimensional electron gas of modulation-doped n-GaAs spacers, as well as defect states in the GaAs environment are the dominant relaxation mechanism. The PC and photoluminescence transients for samples with different morphologies of the InGaAs nanostructures are compared. The relaxation rates are found to be largely dependent on energy disorder due to inhomogeneous distribution of strain, nanostructure size and composition, and piezoelectric fields in and around nanostructures, which have a strong impact on efficiency of carrier exchange between bands of the InGaAs QWRs, GaAs spacers, or wetting layers; presence of local electric fields; and deep traps.

  20. Effects of Polaron and Quantum Confinement on the Nonlinear Optical Properties in a GaAs/Ga1-xAlxAs Quantum Well Wire

    Directory of Open Access Journals (Sweden)

    L. Caroline Sugirtham

    2014-01-01

    Full Text Available The binding energy of a polaron confined in a GaAs/Ga1-xAlxAs quantum well wire is calculated within the framework of the variational technique and Lee-Low Pines approach. The polaron-induced photoionization cross section as a function of normalized photon energy for a on-centre donor impurity in the quantum wire is investigated. The oscillator strength with the geometrical effect is studied taking into account the polaron effects in a GaAs/Ga0.8Al0.2As quantum well wire. The effect of polaron on the third-order susceptibility of third harmonic generation is studied. Our theoretical results are shown to be in good agreement with previous investigations.

  1. Oscillator Strength and Absorption Cross-section of Core-Shell Triangular Quantum Wire for Intersubband Transition

    Science.gov (United States)

    Deyasi, Arpan; Das, N. R.

    Oscillator strength and absorption cross-section of core-shell triangular quantum wire is computed for intersubband optical transition between ground state and first excited state. Kane type band nonparabolicity of first order is considered to study the shift of cross-section peak with incident radiation, and also of the oscillator strength with structural parameters. Results are compared with that obtained from parabolic overestimation. Results show that both oscillator strength and peak magnitude of absorption cross-section decreases with increasing dimension, and the rate is significant when nonparabolic dispersion relation is taken into account. Findings are important for designing optical emitter/detector using core-shell triangular quantum wire.

  2. Electron-phonon interaction effect on the energy levels and diamagnetic susceptibility of quantum wires: Parallelogram and triangle cross section

    Science.gov (United States)

    Khordad, R.; Bahramiyan, H.

    2014-03-01

    In this paper, optical phonon modes are studied within the framework of dielectric continuum approach for parallelogram and triangular quantum wires, including the derivation of the electron-phonon interaction Hamiltonian and a discussion on the effects of this interaction on the electronic energy levels. The polaronic energy shift is calculated for both ground-state and excited-state electron energy levels by applying the perturbative approach. The effects of the electron-phonon interaction on the expectation value of r2 and diamagnetic susceptibility for both quantum wires are discussed.

  3. Polarity effect of electromigration on kinetics of intermetallic compound formation in Pb-free solder V-groove samples

    Science.gov (United States)

    Gan, H.; Tu, K. N.

    2005-03-01

    Intermetallic compound (IMC) formation is critical for the reliability of microelectronic interconnections, especially for flip chip solder joints. In this article, we investigate the polarity effect of electromigration on kinetics of IMC formation at the anode and the cathode in solder V-groove samples. We use V-groove solder line samples, with width of 100 μm and length of 500-700 μm, to study interfacial IMC growth between Cu electrodes and Sn-3.8Ag-0.7Cu (in wt %) solder under different current density and temperature settings. The current densities are in the range of 103 to 104A/cm2 and the temperature settings are 120, 150, and 180 °C. While the same types of IMCs, Cu6Sn5 and Cu3Sn, form at the solder/Cu interfaces independent of the passage of electric current, the growth of the IMC layer has been enhanced by electric current at the anode and inhibited at the cathode, in comparison with the no-current case. We present a kinetic model, based on the Cu mass transport in the sample, to explain the growth rate of IMC at the anode and cathode. The growth of IMC at the anode follows a parabolic growth rule, and we propose that the back stress induced in the IMC plays a significant role. The model is in good agreement with our experimental data. We then discuss the influence of both chemical force and electrical force, and their combined effect on the IMC growth with electric current.

  4. Non-Abelian S U (N -1 ) -singlet fractional quantum Hall states from coupled wires

    Science.gov (United States)

    Fuji, Y.; Lecheminant, P.

    2017-03-01

    The construction of fractional quantum Hall (FQH) states from the two-dimensional array of quantum wires provides a useful way to control strong interactions in microscopic models and has been successfully applied to the Laughlin, Moore-Read, and Read-Rezayi states. We extend this construction to the Abelian and non-Abelian S U (N -1 ) -singlet FQH states at filling fraction ν =k (N -1 )/[N +k (N -1 )m ] labeled by integers k and m , which are potentially realized in multicomponent quantum Hall systems or S U (N ) spin systems. Utilizing the bosonization approach and conformal field theory (CFT), we show that their bulk quasiparticles and gapless edge excitations are both described by an (N -1 ) -component free-boson CFT and the S U (N) k/[U(1 ) ] N -1 CFT known as the Gepner parafermion. Their generalization to different filling fractions is also proposed. In addition, we argue possible applications of these results to two kinds of lattice systems: bosons interacting via occupation-dependent correlated hoppings and an S U (N ) Heisenberg model.

  5. Dirac electrons in graphene-based quantum wires and quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Peres, N M R; Stauber, T [Centro de Fisica e Departamento de Fisica, Universidade do Minho, P-4710-057, Braga (Portugal); Rodrigues, J N B; Lopes dos Santos, J M B [CFP and Departamento de Fisica, Faculdade de Ciencias Universidade do Porto, P-4169-007, Porto (Portugal)

    2009-08-26

    In this paper we analyse the electronic properties of Dirac electrons in finite-size ribbons and in circular and hexagonal quantum dots. We show that due to the formation of sub-bands in the ribbons it is possible to spatially localize some of the electronic modes using a p-n-p junction. We also show that scattering of confined Dirac electrons in a narrow channel by an infinitely massive wall induces mode mixing, giving a qualitative reason for the fact that an analytical solution to the spectrum of Dirac electrons confined in a square box has not yet been found. A first attempt to solve this problem is presented. We find that only the trivial case k = 0 has a solution that does not require the existence of evanescent modes. We also study the spectrum of quantum dots of graphene in a perpendicular magnetic field. This problem is studied in the Dirac approximation, and its solution requires a numerical method whose details are given. The formation of Landau levels in the dot is discussed. The inclusion of the Coulomb interaction among the electrons is considered at the self-consistent Hartree level, taking into account the interaction with an image charge density necessary to keep the back-gate electrode at zero potential. The effect of a radial confining potential is discussed. The density of states of circular and hexagonal quantum dots, described by the full tight-binding model, is studied using the Lanczos algorithm. This is necessary to access the detailed shape of the density of states close to the Dirac point when one studies large systems. Our study reveals that zero-energy edge states are also present in graphene quantum dots. Our results are relevant for experimental research in graphene nanostructures. The style of writing is pedagogical, in the hope that newcomers to the subject will find this paper a good starting point for their research.

  6. Calculation of electrical transport properties and electron entanglement in inhomogeneous quantum wires

    Directory of Open Access Journals (Sweden)

    A A Shokri

    2013-10-01

    Full Text Available In this paper, we have investigated the spin-dependent transport properties and electron entanglement in a mesoscopic system, which consists of two semi-infinite leads (as source and drain separated by a typical quantum wire with a given potential. The properties studied include current-voltage characteristic, electrical conductivity, Fano factor and shot noise, and concurrence. The calculations are based on the transfer matrix method within the effective mass approximation. Using the Landauer formalism and transmission coefficient, the dependence of the considered quantities on type of potential well, length and width of potential well, energy of transmitted electron, temperature and the voltage have been theoretically studied. Also, the effect of the above-mentioned factors has been investigated in the nanostructure. The application of the present results may be useful in designing spintronice devices.

  7. Quantitative absorption spectra of quantum wires measured by analysis of attenuated internal emissions

    Science.gov (United States)

    Yoshita, Masahiro; Okada, Takayuki; Akiyama, Hidefumi; Okano, Makoto; Ihara, Toshiyuki; Pfeiffer, Loren N.; West, Ken W.

    2012-03-01

    An absorption-spectroscopy method that utilizes internal emissions as the source of the probe light was used to measure the absorption spectra of quasi-one-dimensional (q-1D) excitons in T-shaped quantum wires embedded in an optical waveguide. The modal absorption area of the 1D ground-state excitons was estimated to be 0.39 eV cm-1 and was almost independent of temperature in the range 4-150 K. Quantitative evaluation using the absorption spectra revealed that the absorption cross-section per unit length at resonance peak and the spectrally integrated absorption cross-section area per unit length of the 1D ground-state excitons were 1.0 nm and 2.5 × 10-3 eV nm, respectively.

  8. Quasiparticle properties of a coupled quantum-wire electron-phonon system

    DEFF Research Database (Denmark)

    Hwang, E. H.; Hu, Ben Yu-Kuang; Sarma, S. Das

    1996-01-01

    We study leading-order many-body effects of longitudinal-optical phonons on electronic properties of one-dimensional quantum-wire systems. We calculate the quasiparticle properties of a weakly polar one-dimensional electron gas in the presence of both electron-phonon and electron-electron...... interactions, The leading-order dynamical screening approximation (GW approximation) is used to obtain the electron self-energy, the quasiparticle spectral function, and the quasiparticle damping rate in our calculation by treating electrons and phonons on an equal footing. Our theory includes effects (within...... the random-phase approximation) of Fermi statistics, Landau damping, plasmon-phonon mode coupling, phonon renormalization, dynamical screening, and impurity scattering. In general, electron-electron and electron-phonon many-body renormalization effects are found to be nonmultiplicative and nonadditive in our...

  9. Electric and magnetic field effects on the optical absorption of elliptical quantum wire

    Science.gov (United States)

    Karimi, M. J.; Hosseini, M.

    2017-11-01

    In this work, the effects of electric and magnetic fields on the linear, the third-order nonlinear and the total optical absorption coefficients of a typical GaAs/AlGaAs elliptical quantum wire are investigated. Energy eigenvalues and wave functions are calculated using the two-dimensional finite difference method and optical properties are obtained using the compact density matrix approach. The influences of the electric and magnetic fields on the probability densities are described. Results show that the resonant peak values of the optical absorption coefficients are non-monotonic functions of the external fields. Results also indicate that by applying external fields, the magnitude of total optical absorption coefficient reaches to values about 1.5 times higher than that case without external fields.

  10. Nonlinear optical rectification in laterally-coupled quantum well wires with applied electric field

    Science.gov (United States)

    Liu, Guanghui; Guo, Kangxian; Zhang, Zhongmin; Hassanbadi, Hassan; Lu, Liangliang

    2017-03-01

    Nonlinear optical rectification coefficient χ0(2) in laterally-coupled AlxGa1-xAs/GaAs quantum well wires with an applied electric field is theoretically investigated using the effective mass approximation as well as the numerical energy levels and wavefunctions of electrons. We find that χ0(2) is greatly influenced by the electric field as well as both the distance and the radius of the coupled system. A blue shift of χ0(2) with increasing electric field is exhibited while a red shift followed by a blue shift with increasing distance or radius is exhibited. A nonmonotonic behavior can be found in the resonant peak values of χ0(2) along with the increase of the electric field, the distance or the radius. One or two of the following physical mechanisms: the increased localization of the ground and first-excited states, the reduced coupling and the reduced quantum confinement effect are applied to elucidate the results above. Our results play a potential role in infrared photodetectors based on the coupled system.

  11. Functionality of bismuth sulfide quantum dots/wires-glass nanocomposite as an optical current sensor with enhanced Verdet constant

    Science.gov (United States)

    Panmand, Rajendra P.; Kumar, Ganapathy; Mahajan, Satish M.; Kulkarni, Milind V.; Amalnerkar, D. P.; Kale, Bharat B.; Gosavi, Suresh. W.

    2011-02-01

    We report optical studies with magneto-optic properties of Bi2S3 quantum dot/wires-glass nanocomposite. The size of the Q-dot was observed to be in the range 3-15 nm along with 11 nm Q-wires. Optical study clearly demonstrated the size quantization effect with drastic band gap variation with size. Faraday rotation tests on the glass nanocomposites show variation in Verdet constant with Q-dot size. Bi2S3 Q-dot/wires glass nanocomposite demonstrated 190 times enhanced Verdet constant compared to the host glass. Prima facie observations exemplify the significant enhancement in Verdet constant of Q-dot glass nanocomposites and will have potential application in magneto-optical devices.

  12. Optical gain for the interband optical transition in InAsP/InP quantum well wire in the influence of laser field intensity

    Energy Technology Data Exchange (ETDEWEB)

    Saravanan, S. [Dept.of Physics, GTN Arts College, Dindigul-624 005. India (India); Peter, A. John, E-mail: a.john.peter@gmail.com [P.G & Research Dept.of Physics, Government Arts College, Melur-625 106. Madurai. India (India)

    2016-05-23

    Intense high frequency laser field induced electronic and optical properties of heavy hole exciton in the InAs{sub 0.8}P{sub 0.2}/InP quantum wire is studied taking into account the geometrical confinement effect. Laser field related exciton binding energies and the optical band gap in the InAs{sub 0.8}P{sub 0.2}/InP quantum well wire are investigated. The optical gain, for the interband optical transition, as a function of photon energy, in the InAs{sub 0.8}P{sub 0.2}/InP quantum wire, is obtained in the presence of intense laser field. The compact density matrix method is employed to obtain the optical gain. The obtained optical gain in group III-V narrow quantum wire can be applied for achieving the preferred telecommunication wavelength.

  13. Manifestation of the composition inhomogeneity of Zn1 - x Mg x Te quantum wires in Raman spectra

    Science.gov (United States)

    Zavaritskaya, T. N.; Kucherenko, I. V.; Karczewski, G.; Mel'nik, N. N.; Vinogradov, V. S.; Zaleszczyk, W.

    2011-02-01

    The resonant Raman spectra of Zn1 - x Mg x Te quantum wires have been investigated. The dependences of the frequencies of longitudinal optical phonons of the ZnTe-like and MgTe-like modes (LO1 and LO2) on the photon energy have been found. The character of these dependences correlates with the variation in the frequencies of optical phonons of the Zn1 - x Mg x Te alloys on the composition ( x). This gives grounds to assume that the quantum wires are inhomogeneous in the composition. This assumption is also confirmed by the fact that the intensity ratio of the LO2 and LO1 modes in the Raman spectra increases with increasing excitation energy.

  14. Pressure induced optical absorption and refractive index changes of a shallow hydrogenic impurity in a quantum wire

    Science.gov (United States)

    Arunachalam, N.; John Peter, A.; Woo Lee, Chang

    2011-10-01

    Pressure induced binding energy of a hydrogenic impurity in an InAs/GaAs quantum wire is investigated. Calculations are performed using Bessel functions as an orthonormal basis within a single band effective mass approximation using variational method. Photoionization cross-section of the hydrogenic impurity in the influence of pressure is studied. The total optical absorption and the refractive index changes as a function of normalized photon energy between the ground and the first excited state in the presence of pressure are analyzed. The optical absorption coefficients and the refractive index changes strongly depend on the incident optical intensity and pressure. The occurred blue shift of the resonant peak due to the pressure gives the information about the variation of two energy levels in the quantum well wire. The optical absorption coefficients and the refractive index changes are strongly dependent on the incident optical intensity and the pressure.

  15. The polarity effect of electromigration on intermetallic compound formation and back stress in v-groove solder lines

    Science.gov (United States)

    Ou, Shengquan

    2005-07-01

    The trend of the miniaturization of VLSI and electronic packaging toward higher input/output density, smaller feature size and greater performance makes electromigration a serious reliability concern in flip chip technology. As an integral part of the joint, intermetallic compound (IMC) formation is very important to achieve good joint strength. However, the effect of electromigration on the IMC formation is a subject in which still very little is known. We utilize solder v-groove samples etched on (001) Si wafer with 100 mum opening to study the polarity effect of electromigration on IMC formation in solder joints. We focus on the interaction between chemical and electrical forces, and the influence of interface morphology on the IMC dissolution. The current densities used are from 103 to 104 A/cm2 and the temperature settings are in the range of 120°C to 180°C. We have found in both 95.5Sn3.8Ag0.7Cu/Cu and 96.5Sn3.5Ag systems the growth of the IMC has been enhanced by electric current at the anode and inhibited at the cathode. For Ni-Sn compound, kinetic analysis using the motion of the two interfaces gives the general formula of the growth rate as dXdt=aX + b. We have introduced the concept of mean-field theory and the classic model of Zener's precipitation growth into the discussion of the Cu-Sn compound growth under electromigration. A parabolic dependence of the IMC growth on time at the anode is derived as x 2 ≅ (Cm-Ce)2 (Cs-Ce)2 Dt. The interaction between chemical and electrical forces brings a dynamic equilibrium in IMC dissolution at the cathode. This has been proved theoretically and experimentally. A new critical product has been derived from this dynamic equilibrium, which can provide us a critical IMC thickness before voids formation at a given current density. Our study shows the dissolution rate of Cu with current density 5x103 A/cm2 at 150°C is about 0.076 mum/hr. We also notice that the interface morphology plays an important role in the IMC

  16. The quantum-mechanical basis of an extended Landau-Lifshitz-Gilbert equation for a current-carrying ferromagnetic wire

    OpenAIRE

    Edwards, D. M.; Wessely, O.

    2008-01-01

    An extended Landau-Lifshitz-Gilbert (LLG) equation is introduced to describe the dynamics of inhomogeneous magnetization in a current-carrying wire. The coefficients of all the terms in this equation are calculated quantum-mechanically for a simple model which includes impurity scattering. This is done by comparing the energies and lifetimes of a spin wave calculated from the LLG equation and from the explicit model. Two terms are of particular importance since they describe non-adiabatic spi...

  17. Phonon Confinement Effect on the Binding Energy of a Hydrogenic Impurity in Quantum Wires in the Electric and Magnetic Fields

    Science.gov (United States)

    Shahbandari, Abbas

    The effect of phonon confinement on ground state binding energy of bound polaron in polar quantum wires with a finite confining potential investigated by Landau-Pekar variation technique. The effect of external electric and magnetic fields is taken into account as well. The obtained results show that the polar optical phonon confinement leads to a considerable enhancement of the polaron effect and these corrections increase with increasing of applied fields.

  18. Temperature dependence of scattering phases and Friedel phase discontinuity in quantum wires

    Science.gov (United States)

    Vargiamidis, Vassilios; Fessatidis, Vassilios

    2011-07-01

    Two important issues concerning the scattering phases in a quantum wire with an attractive scatterer are investigated. We consider the case of two quasibound states which couple to a scattering channel and give rise to two Fano resonances. First, we examine the effects of temperature on the phase of the transmission amplitude and the Friedel phase. It is shown that temperature effects tend to smear sharp features of the transmission phase; namely, the phase drops become less than π, and acquire finite widths which increase linearly in the low-temperature regime. The influence of temperature on the Friedel phase and density of states becomes stronger as the Fano resonance becomes narrower. Second, we examine the behavior of the Friedel phase when the energy of the incident electron crosses an infinitely narrow Fano resonance, forming bound state in the continuum. It is shown that the Friedel phase exhibits abrupt jump of π at this energy. We discuss this odd behavior in relation to the Friedel sum rule and point out its consequences on the charge in the scattering region.

  19. Combined effects of magnetic and electric fields on the interband optical transitions in InAs/InP quantum wire

    Science.gov (United States)

    Saravanan, S.; John Peter, A.; Lee, ChangWoo

    2015-03-01

    Combined effects of magnetic and electric fields on the confined exciton in an InAs1-xPx/InP (x=0.2) quantum well wire are investigated taking into account the geometrical confinement effect. Variational formulism, within the frame work of effective mass approximation, is applied to obtain the exciton binding energy. The second order harmonic generation and the optical gain are carried out using compact density method. The strain effects are included with the confinement potential in the Hamiltonian. The energy difference of the ground and the first excited state is found in the presence of magnetic and electric fields taking into the consideration of spatial confinement effect. The result shows that the optical properties are more influenced taking into account the effects of geometrical confinement, magnetic field and electric field. It is shown that the telecommunication wavelength can be achieved with the suitable doping barrier material with the wire material and the external perturbations.

  20. Classical and quantum binding of a particle with arbitrary spin in the magnetic field of a current-carrying wire: a simple guide for atoms

    Science.gov (United States)

    Schmiedmayer, Jörg; Scrinzi, Armin

    1996-06-01

    A neutral atom with a magnetic moment can be bound to, and guided along, a current-carrying wire. The atom is attracted to regions of high field strength (high-field seeking state) and repelled from the wire by the centrifugal barrier. In the classical regime the atoms move in Kepler-like orbits. In the quantum regime, the system resembles a two-dimensional hydrogen atom in Rydberg-like states. The wire replaces the nucleus and the atom plays the role of the electron. We give a quantum mechanical and a classical description of the system. We rigorously prove the existence of infinitely many bound states for zero or finite wire cross section and any spin (F) of the atom. The bound-state energies closely follow a Coulomb-like behaviour with an effective angular momentum, 1355-5111/8/3/029/img5.

  1. Influence of composition and substrate miscut on the evolution of {105}-terminated in-plane Si1−xGex quantum wires on Si(001

    Directory of Open Access Journals (Sweden)

    H. Watzinger

    2014-07-01

    Full Text Available Isolated in-plane wires on Si(001 are promising nanostructures for quantum transport applications. They can be fabricated in a catalyst-free process by thermal annealing of self-organized Si1−xGex hut clusters. Here, we report on the influence of composition and small substrate miscuts on the unilateral wire growth during annealing at 570 °C. The addition of up to 20% of Si mainly affects the growth kinetics in the presence of energetically favorable sinks for diffusing Ge atoms, but does not significantly change the wire base width. For the investigated substrate miscuts of <0.12°, we find geometry-induced wire tapering, but no strong influence on the wire lengths. Miscuts <0.02° lead to almost perfect quantum wires terminated by virtually step-free {105} and {001} facets over lengths of several 100 nm. Generally, the investigated Si1−xGex wires are metastable: Annealing at ≥600 °C under otherwise identical conditions leads to the well-known coexistence of Si1−xGex pyramids and domes.

  2. The Use of Fiberglass and Ceramic Cylinders to Support the Root Pass in C-Steel Welds with a Double-V Groove

    Directory of Open Access Journals (Sweden)

    Ricardo Fernandes Gurgel

    2015-09-01

    Full Text Available Abstract The aim of this work is to evaluate the effectiveness of fiberglass and ceramic fiber cylinders as root-pass weld backing for a double-V groove in 16 mm-thick carbon steel. Three different cylinder diameters were tested: 4.8, 9.5 mm (fiberglass and 6.4 mm (ceramic fiber. The welding process used was GMAW. The welding technique and the following process variables were investigated: root opening, current and travel speed. The results show that cylindrical fiberglass and ceramic fiber backings not only have excellent refractory properties, but also seal the root opening and contain the weld pool sufficiently to produce a root bead free of discontinuities and with a satisfactory shape and geometry. Working points were defined, together with a possible operating range for the welding parameters. It was concluded that cylindrical fiberglass and ceramic fiber weld backings hold great promise for use in root-pass welds in double-V grooves in applications in the naval and metallurgical industry.

  3. The influence of polar optical phonon confinement on the binding energy of a hydrogenic impurity in quantum wires in the perpendicular electric and magnetic fields

    Science.gov (United States)

    Vartanian, A. L.; Shahbandari, A.; Yeranosyan, M. A.; Kirakosyan, A. A.

    2012-03-01

    The hydrogenic impurity binding energy in cylindrical quantum well wire with a finite confining potential including both barriers of finite height and an applied electric and magnetic fields are studied. The polaron effect on the ground-state binding energy are investigated by means of Landau-Pekar variation technique. The results for the binding energy as well as polaronic correction with taking into account polar optical phonon confinement effect are obtained as a function of the applied fields for different position of the impurity. Our calculations are compared with previous results in quantum wires of comparable dimensions.

  4. Coupling of single quantum emitters to plasmons propagating on mechanically etched wires

    DEFF Research Database (Denmark)

    Kumar, Shailesh; Huck, Alexander; Lu, Ying-Wei

    2013-01-01

    We demonstrate the coupling of a single nitrogen vacancy center in a nanodiamond to propagating plasmonic modes of mechanically etched silver nanowires. The mechanical etch is performed on single crystalline silver nanoplates by the tip of an atomic force microscope cantilever to produce wires wi...

  5. Thermoelectric power in carbon nanotubes and quantum wires of nonlinear optical, optoelectronic, and related materials under strong magnetic field : Simplified theory and relative comparison

    NARCIS (Netherlands)

    Ghatak, K.P.; Bhattacharya, S.; Bhowmik, S.; Benedictus, R.; Choudhury, S.

    2008-01-01

    We study thermoelectric power under strong magnetic field (TPM) in carbon nanotubes (CNTs) and quantum wires (QWs) of nonlinear optical, optoelectronic, and related materials. The corresponding results for QWs of III-V, ternary, and quaternary compounds form a special case of our generalized

  6. Electric and magnetic field modulated energy dispersion, conductivity and optical response in double quantum wire with spin-orbit interactions

    Science.gov (United States)

    Karaaslan, Y.; Gisi, B.; Sakiroglu, S.; Kasapoglu, E.; Sari, H.; Sokmen, I.

    2018-02-01

    We study the influence of electric field on the electronic energy band structure, zero-temperature ballistic conductivity and optical properties of double quantum wire. System described by double-well anharmonic confinement potential is exposed to a perpendicular magnetic field and Rashba and Dresselhaus spin-orbit interactions. Numerical results show up that the combined effects of internal and external agents cause the formation of crossing, anticrossing, camel-back/anomaly structures and the lateral, downward/upward shifts in the energy dispersion. The anomalies in the energy subbands give rise to the oscillation patterns in the ballistic conductance, and the energy shifts bring about the shift in the peak positions of optical absorption coefficients and refractive index changes.

  7. Optical anisotropy of InGaAs quantum wire arrays on vicinal (111)B GaAs

    Science.gov (United States)

    Kawazu, Takuya

    2016-10-01

    We studied the optical anisotropy of InGaAs quantum wire (QWR) arrays on vicinal (111)B GaAs. Polarized photoluminescence (PL) studies showed that the PL is polarized preferentially along [1-10], where the polarization degree ρ is about 9.4%. We also theoretically investigated the electronic states of the InGaAs QWR arrays to clarify how the optical anisotropy is affected by (1) the corrugated structure, (2) the strain effect including piezoelectricity, and (3) the thickness difference of the InGaAs layers on the two facets of the corrugated structure. While ρ for the corrugated structure is almost the same as that for a flat quantum well structure, the strain effects and the thickness difference result in the increases of ρ by about 1.9 and 2.5 times. The calculated results were compared to the experimental data. It was found that the effects of the strain and the thickness difference are important to explain the optical anisotropy of the InGaAs QWR arrays.

  8. Temperature tunability of quantum emitter - cavity coupling in a photonic wire microcavity with shielded sidewall loss

    CERN Document Server

    Bernard, M

    2016-01-01

    Recent technological advancements have allowed to implement in solid-state cavity-based devices phenomena of quantum nature such as vacuum Rabi splitting, controllable single photon emission and quantum entanglement. For a sufficiently strong coupling between a quantum emitter and a cavity, large quality factors ($Q$) along with small modal volume ($V_{eff}$) are essential. Here we show that by applying a 5nm Al coating to the sidewalls of a submicrometer-sized Fabry-P\\'{e}rot microcavity, the cavity $Q$ can be temperature-tuned from few hundreds at room temperatures to 2$\\times$10$^5$ below 30~K. This is achieved by, first, a complete shielding of the sidewall loss with ideally reflecting lateral metallic mirrors and, secondly, a dramatic decrease of the cavity's axial loss for small-sized devices due to the largely off-axis wavevector within the multilayered structure. Our findings offer a novel temperature-tunable platform to study quantum electrodynamical phenomena of emitter-cavity coupling. We demonstra...

  9. Ground state structure and conductivity of quantum wires of infinite length and finite width

    Science.gov (United States)

    Malet, F.; Pi, M.; Barranco, M.; Lipparini, E.

    2005-11-01

    We have studied the ground state structure of quantum strips within the local spin-density approximation, for a range of electronic densities between ˜5×104 and 2×106cm-1 and several strengths of the lateral confining potential. The results have been used to address the conductance G of quantum strips. At low density, when only one subband is occupied, the system is fully polarized and G takes a value close to 0.7(2e2/h) , decreasing with increasing electron density in agreement with experiments. At higher densities the system becomes paramagnetic and G takes a value near (2e2/h) , showing a similar decreasing behavior with increasing electron density. In both cases, the physical parameter that determines the value of the conductance is the ratio K/K0 of the compressibility of the system to the free one.

  10. Epitaxial growth of GaSb on V-grooved Si (001) substrates with an ultrathin GaAs stress relaxing layer

    Science.gov (United States)

    Li, Qiang; Lai, Billy; Lau, Kei May

    2017-10-01

    We report epitaxial growth of GaSb nano-ridge structures and planar thin films on V-groove patterned Si (001) substrates by leveraging the aspect ratio trapping technique. GaSb was deposited on {111} Si facets of the V-shaped trenches using metal-organic chemical vapor deposition with a 7 nm GaAs growth initiation layer. Transmission electron microscopy analysis reveals the critical role of the GaAs layer in providing a U-shaped surface for subsequent GaSb epitaxy. A network of misfit dislocations was uncovered at the GaSb/GaAs hetero-interface. We studied the evolution of the lattice relaxation as the growth progresses from closely pitched GaSb ridges to coalesced thin films using x-ray diffraction. The omega rocking curve full-width-at-half-maximum of the resultant GaSb thin film is among the lowest values reported by molecular beam epitaxy, substantiating the effectiveness of the defect necking mechanism. These results thus present promising opportunities for the heterogeneous integration of devices based on 6.1 Å family compound semiconductors.

  11. Tunneling into quantum wires: Regularization of the tunneling Hamiltonian and consistency between free and bosonized fermions

    Science.gov (United States)

    Filippone, Michele; Brouwer, Piet W.

    2016-12-01

    Tunneling between a point contact and a one-dimensional wire is usually described with the help of a tunneling Hamiltonian that contains a δ function in position space. Whereas the leading-order contribution to the tunneling current is independent of the way this δ function is regularized, higher-order corrections with respect to the tunneling amplitude are known to depend on the regularization. Instead of regularizing the δ function in the tunneling Hamiltonian, one may also obtain a finite tunneling current by invoking the ultraviolet cutoffs in a field-theoretic description of the electrons in the one-dimensional conductor, a procedure that is often used in the literature. For the latter case, we show that standard ultraviolet cutoffs lead to different results for the tunneling current in fermionic and bosonized formulations of the theory, when going beyond leading order in the tunneling amplitude. We show how to recover the standard fermionic result using the formalism of functional bosonization and revisit the tunneling current to leading order in the interacting case.

  12. Exchange-correlation effects on quantum wires with spin-orbit interactions under the influence of in-plane magnetic fields

    Science.gov (United States)

    Malet, Francesc; Pi, Martí; Barranco, Manuel; Serra, Llorenç; Lipparini, Enrico

    2007-09-01

    Within the noncollinear local spin-density approximation, we have studied the ground state structure of a parabolically confined quantum wire submitted to an in-plane magnetic field, including both Rashba and Dresselhaus spin-orbit interactions. We have explored a wide range of linear electronic densities in the weak (strong) coupling regimes that appear when the ratio of spin-orbit to confining energy is small (large). These results are used to obtain the conductance of the wire. In the strong coupling limit, the interplay between the applied magnetic field—irrespective of the in-plane direction, the exchange-correlation energy, and the spin-orbit energy—produces anomalous plateaus in the conductance vs linear density plots that are otherwise absent, or washes out plateaus that appear when the exchange-correlation energy is not taken into account.

  13. Hydrostatic pressure on optical absorption and refractive index changes of a shallow hydrogenic impurity in a GaAs/GaAlAs quantum wire

    Science.gov (United States)

    Santhi, M.; John Peter, A.; Yoo, ChangKyoo

    2012-08-01

    The effect of hydrostatic pressure on the binding energy of a hydrogenic impurity in a GaAs/GaAlAs quantum wire is discussed. Calculations have been performed using Bessel functions as an orthonormal basis within a single band effective mass approximation. Pressure induced photoionization cross section of the hydrogenic impurity is investigated. The total optical absorption and the refractive index changes as a function of normalized photon energy between the ground and the first excited state in the presence of pressure are analysed. The optical absorption coefficients and the refractive index changes strongly depend on the incident optical intensity and the pressure.

  14. Quantum optics with quantum dots in photonic nanowires

    DEFF Research Database (Denmark)

    We will review recent studies performed on InAs quantum dots embedded in GaAs photonic wires, which highlight the strong interest of the photonic wire geometry for quantum optics experiments and quantum optoelectronic devices.......We will review recent studies performed on InAs quantum dots embedded in GaAs photonic wires, which highlight the strong interest of the photonic wire geometry for quantum optics experiments and quantum optoelectronic devices....

  15. Nuclear Quantum Effects in H+ and OH- Diffusion Along Confined Water Wires from Ab Initio Path Integral Molecular Dyanmics

    Science.gov (United States)

    Rossi, Mariana; Ceriotti, Michele; Manolopoulos, David

    Diffusion of H+ and OH- along water wires provides an efficient mechanism for charge transport that is exploited by biological systems and shows promise in technological applications. However, what is lacking for a better control and design of these systems is a thorough theoretical understanding of the diffusion process at the atomic scale. Here we consider H+ and OH- in finite water wires using density functional theory. We employ machine learning techniques to identify the charged species, thus obtaining an agnostic definition of the charge. We employ thermostated ring polymer molecular dynamics and extract a ``universal'' diffusion coefficient from simulations with different wire sizes by considering Langevin dynamics on the potential of mean force of the charged species. In the classical case, diffusion coefficients depend significantly on the potential energy surface, in particular on how dispersion forces modulate O-O distances. NQEs, however, make the diffusion less sensitive to the underlying potential and geometry of the wire, presumably making them more robust to environment fluctuations.

  16. The Einstein relation in quantum wires of III-V, ternary, and quaternary materials in the presence of light waves : Simplified theory, relative comparison, and suggestion for experimental determination

    NARCIS (Netherlands)

    Ghatak, K.P.; Bhattacharya, S.; Bhowmik, S.; Benedictus, R.; Choudhury, S.

    2008-01-01

    We study the Einstein relation for the diffusivity to mobility ratio (DMR) in quantum wires (QWs) of III-V, ternary, and quaternary materials in the presence of light waves, whose unperturbed energy band structures are defined by the three band model of Kane. It has been found, taking n-InAs,

  17. Optimization of the confinement energy of quantum-wire states in T-shaped GaAs/AlxGa1-xAs structures

    DEFF Research Database (Denmark)

    Langbein, Wolfgang Werner; Gislason, Hannes; Hvam, Jørn Märcher

    1996-01-01

    We report on an optimization of the wire confinement energies of the confined electronic states at the T-shaped intersection of GaAs and AlxGa1-xAs quantum wells. These structures can be produced by the cleaved edge overgrowth technique. We present an analytical model for the confinement to give...... insight into the basic mechanism. The optimization of the confinement energy is done by calculations in a six-band k . p approximation for the valence band and in an isotropic effective-mass approximation for the conduction band. The confined valence-band states are only weakly bound at the T......-shaped intersection due to the large and anisotropic hole effective masses. Employing optimized sample parameters, confinement energies for the free-electron-hole pairs are nearly doubled compared to symmetric structures, and 34 meV are predicted for a 3-nm overgrown GaAs well. This is expected to be further enhanced...

  18. Mid-infrared emission in InxGa1-xAs/GaAs T-shaped quantum wire lasers and its indium composition dependence

    Science.gov (United States)

    Ridene, Said

    2018-03-01

    In this work, the emission wavelength has been extended out to 1.3, 1.5, and 2.2 μm for InxGa1-xAs/GaAs T-shaped quantum wire (TQWR) using multi-band k.p model and variational formalism. We have investigated the impact of the indium composition on the performance of a series of TQWR through a calculation of the optical gain and transition energies. It is found that the optical gain and the emission wavelength are more influenced taking into account the effect of the indium concentration and persisted up at room temperature (RT). The results could open the way to the development of laser communication systems operating at long wavelengths and fabricated from TQWRs structure.

  19. Low temperature behavior of thermodynamic properties of 1D quantum wire under the Rashba spin-orbit interaction and magnetic field

    Science.gov (United States)

    Khordad, R.; Rastegar Sedehi, H. R.

    2018-01-01

    In this work, we study the effects of the Rashba spin-orbit interaction (SOI) and applied magnetic field on thermodynamic properties of a quasi-one-dimensional quantum wire at low temperatures. To this end, we first present an explicit relation for partition function. Then, we give analytical expressions for the mean energy, specific heat, free energy, and entropy of the system. It is found that the specific heat shows a peak structure in the presence of SOI and then reduces to zero. The peak width of the specific heat depends on the strength of SOI. At low temperatures, the entropy reduces with increasing magnetic field in the presence of SOI, but at higher temperatures, it remains almost independent of the magnetic field. The peak of specific heat occurs at a certain value of the magnetic field which depends on the temperature.

  20. Transmission electron microscopy and photoluminescence characterization of InGaAs strained quantum wires on GaAs vicinal (110) substrates

    CERN Document Server

    Shim, B R; Ota, T; Kobayashi, K; Maehashi, K; Nakashima, H; Lee, S Y

    1999-01-01

    We have used transmission electron microscopy (TEM) and photoluminescence (PL) to study InGaAs/AlGaAs strained quantum wires (QWRs) grown by molecular beam epitaxy (MBE) on GaAs vicinal (110) substrates. The cross-sectional TEM image reveals that InGaAs QWRs structures are naturally formed on AlGaAs giant steps. In the plan-view TEM images, the fringe pattern in the giant-step region is observed for In sub x Ga sub 1 sub - sub x As layers with x<= 0.4 We measured the separation of the fringe in the plan-view TEM images and compared the result with the calculated fringe separation. From this result, we conclude that the fringes observed in the plan-view TEM images are moire fringes. PL spectra of the InGaAs QWRs samples reveal 80-meV shifts to lower energy with respect to the spectrum of a quantum well (QWL) grown on a (001) substrate under the same conditions. We also measured the polarization anisotropy of the PL spectra from the QWRs. The PL peak shifts systematically toward higher energy with decreasing...

  1. Impurity-related optical properties in rectangular-transverse section GaAs-Ga{sub 1-x}Al{sub x}As quantum well wires: Hydrostatic pressure and electric field effects

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, J.W.; Duque, C.A. [Instituto de Fisica, Universidad de Antioquia, AA 1226, Medellin (Colombia); Lopez, S.Y. [Facultad de Educacion, Universidad de Antioquia, AA 1226, Medellin (Colombia); Rodriguez, A.H. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico (UNAM), Apdo. Postal 20-364, San Angel 01000, Mexico DF (Mexico); Porras-Montenegro, N. [Departamento de Fisica, Universidad del Valle, AA 25360, Cali (Colombia)

    2007-01-15

    Using a variational procedure within the effective mass approximation, we have calculated the influence of an applied electric field and hydrostatic pressure on the shallow-impurity-related optical properties in a rectangular-transverse section GaAs-Ga{sub 1-x}Al{sub x}As quantum well wire. The electric field is applied in the plane of the transverse section of the wire and different angular directions have been considered. The results presented are for the impurity binding energy, its corresponding density of impurity states, and impurity-related transition energy and polarizability. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Wire chamber

    CERN Multimedia

    1967-01-01

    Magnetoscriptive readout wire chamber.Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  3. Wire Chamber

    CERN Multimedia

    Magnetoscriptive readout wire chamber. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  4. wire chamber

    CERN Multimedia

    Proportional multi-wire chamber. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle. Proportional wire chambers allow a much quicker reading than the optical or magnetoscriptive readout wire chambers.

  5. The mechanism of formation of the interlayer quantum wires in zinc-doped Bi2Te3

    Directory of Open Access Journals (Sweden)

    Alieva A. P.

    2012-06-01

    Full Text Available Nanowires formation process on a (0001 surface of Bi2Te3 is studied. It has been established that on interlayer surface Te(1—Te(1 there is a process of migration of atoms, moving and coagulation of clusters on the basis of Zn atoms. As a result of diffusion-limited aggregation the structures with quantum dots are formed, from which nanowires are self-organized. Such superficial structures play regulating role in working out the topological insulators based on A2VB3VI and increase thermoelectric efficiency of a composite.

  6. Zeeman effects on the tunneling spectra of a ferromagnetic d-wave superconductor in contact with a quantum wire

    Energy Technology Data Exchange (ETDEWEB)

    Emamipour, Hamidreza, E-mail: h_emamipour@yahoo.com [Department of Physics, Ilam University, Ilam (Iran, Islamic Republic of); Mehrabzad, Narges [Islamic Azad University, Central Tehran Branch, Tehran (Iran, Islamic Republic of)

    2016-07-15

    We study tunneling conductance in a quantum wire–insulator–ferromagnetic d-wave superconductor junction. The results show that exchange field of superconductor has a strong impact on tunneling spectra depending on the junction parameters. We have found a gap like structure in the tunneling limit when we have an interface normal to the (100) axis of superconductor. In the case of (110) axis of superconductor, there is not any zero- bias conductance peaks in tunneling spectra. For a metallic junction the dips disappear.

  7. wire chamber

    CERN Multimedia

    Was used in ISR (Intersecting Storage Ring) split field magnet experiment. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  8. wire chamber

    CERN Multimedia

    1985-01-01

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  9. wire chamber

    CERN Multimedia

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  10. Wire chamber

    CERN Multimedia

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  11. CdSe quantum dot in vertical ZnSe nanowire and photonic wire for efficient single-photon emission

    DEFF Research Database (Denmark)

    Cremel, Thibault; Bellet-Amalric, Edith; Cagnon, Laurent

    as a single photon source. We have grown vertically oriented ZnSe NWs (with typical diameter of 10 nm) by molecular beam epitaxy on a ZnSe(111)B buffer layer. The growth of a ZnMgSe passivating shell increases the (otherwise weak) ZnSe near-band-edge luminescence by two orders of magnitude. This has allowed...... us to observe luminescence for the first time from CdSe/ZnSe NW-QDs in the (111) direction. We managed to obtain a low NW density (~ 1 NW/4 μm2) so that single NW-QDs can be directly studied on the as-grown sample. Exciton, biexciton and charged exciton lines are clearly identified. Then we obtained...... conformal dielectric coating of Al2O3 on the NW-QDs using Atomic Layer Deposition so that a photonic wire is formed with the CdSe QD deterministically positioned on its axis. The collection enhancement effect is studied by measuring the emission (with pulse excitation, at saturation intensity) of single...

  12. Derivation of the probability distribution function for the local density of states of a disordered quantum wire via the replica trick and supersymmetry

    Science.gov (United States)

    Bunder, J. E.; McKenzie, Ross H.

    2001-01-01

    We consider the statistical properties of the local density of states of a one-dimensional Dirac equation in the presence of various types of disorder with Gaussian white-noise distribution. It is shown how either the replica trick or supersymmetry can be used to calculate exactly all the moments of the local density of states. Careful attention is paid to how the results change if the local density of states is averaged over atomic length scales. For both the replica trick and supersymmetry the problem is reduced to finding the ground state of a zero-dimensional Hamiltonian which is written solely in terms of a pair of coupled "spins" which are elements of u(1,1). This ground state is explicitly found for the particular case of the Dirac equation corresponding to an infinite metallic quantum wire with a single conduction channel. The calculated moments of the local density of states agree with those found previously by Al'tshuler and Prigodin [Sov. Phys. JETP 68 (1989) 198] using a technique based on recursion relations for Feynman diagrams.

  13. Isotropic Hall effect and ''freeze-in'' of carriers in the InGaAs self-assembled quantum wires

    Energy Technology Data Exchange (ETDEWEB)

    Kunets, Vas. P.; Prosandeev, S.; Mazur, Yu. I.; Ware, M. E.; Teodoro, M. D.; Dorogan, V. G.; Lytvyn, P. M.; Salamo, G. J. [Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

    2011-10-15

    Using molecular beam epitaxy, we prepared an anisotropic media consisting of InGaAs quantum wires epitaxially grown on GaAs (311)A. Anisotropy is observed in the lateral conductivity and photoluminescence polarization. However, an isotropic Hall effect is observed in the same samples. We show that the Hall effect in this anisotropic heterostructure remains isotropic regardless of the change of the doping in GaAs barriers and regardless of the InGaAs coverage, whereas the conductivity anisotropy experiences a strong change under these actions. In addition, we observed an anomalous increase in carrier density, ''freeze-in,'' at low temperatures. In order to explain this, we generalized the theory of Look [D. C. Look, Phys. Rev B 42, 3578 (1990)] by considering the low field magneto-transport in anisotropic media. This theory confirms that the Hall constant remains isotropic in anisotropic semiconductor heterostructures, agreeing with our experiment and explains the anomalous behavior of carriers as a result of multi-band conductivity.

  14. Pressure-induced interband optical transitions in an InAs0.8P0.2/InP quantum wire

    Science.gov (United States)

    Saravanan, S.; Peter, A. John; Lee, Chang Woo

    2015-12-01

    Hydrostatic pressure-induced exciton binding energy in an InAs0.8P0.2/InP quantum well wire is investigated taking into account the geometrical confinement effect. Numerical calculations are carried out using variational approach within the single-band effective-mass approximation. The compressive strain contribution to the confinement potential is included throughout the calculations. The energy difference of the ground and the first excited state is found with the consideration of spatial confinement effect in the influence of pressure. The second-order susceptibility of harmonic generation is carried out using the compact density method. The optical gain as a function of incident photon energy is computed in the presence of the hydrostatic pressure. The result shows that the range of wavelength for the potential applications of telecommunications (1.3-1.55 μm) can be obtained by the application of the hydrostatic pressure. We believe that the obtained results can be applied for tuning the ranges of fibre optical wavelength in telecommunications.

  15. Quantum Optics with Quantum Dots in Photonic Nanowires

    DEFF Research Database (Denmark)

    Gérard, J. M.; Claudon, J.; Bleuse, J.

    2012-01-01

    We review recent experimental and theoretical results, which highlight the strong interest of the photonic wire geometry for solid-state quantum optics and quantum optoelectronic devices.......We review recent experimental and theoretical results, which highlight the strong interest of the photonic wire geometry for solid-state quantum optics and quantum optoelectronic devices....

  16. Correlated atomic wires on substrates. II. Application to Hubbard wires

    Science.gov (United States)

    Abdelwahab, Anas; Jeckelmann, Eric; Hohenadler, Martin

    2017-07-01

    In the first part of our theoretical study of correlated atomic wires on substrates, we introduced lattice models for a one-dimensional quantum wire on a three-dimensional substrate and their approximation by quasi-one-dimensional effective ladder models [Abdelwahab et al., preceding paper, Phys. Rev. B 96, 035445 (2017), 10.1103/PhysRevB.96.035445]. In this second part, we apply this approach to the case of a correlated wire with a Hubbard-type electron-electron repulsion deposited on an insulating substrate. The ground-state and spectral properties are investigated numerically using the density-matrix renormalization group method and quantum Monte Carlo simulations. As a function of the model parameters, we observe various phases with quasi-one-dimensional low-energy excitations localized in the wire, namely, paramagnetic Mott insulators, Luttinger liquids, and spin-1 /2 Heisenberg chains. The validity of the effective ladder models is assessed for selected parameters by studying the dependence of results on the number of legs and comparing to the full three-dimensional model. We find that narrow ladder models accurately reproduce the quasi-one-dimensional excitations of the full three-dimensional model but predict only qualitatively whether excitations are localized around the wire or delocalized in the three-dimensional substrate.

  17. Quantum

    CERN Document Server

    Al-Khalili, Jim

    2003-01-01

    In this lively look at quantum science, a physicist takes you on an entertaining and enlightening journey through the basics of subatomic physics. Along the way, he examines the paradox of quantum mechanics--beautifully mathematical in theory but confoundingly unpredictable in the real world. Marvel at the Dual Slit experiment as a tiny atom passes through two separate openings at the same time. Ponder the peculiar communication of quantum particles, which can remain in touch no matter how far apart. Join the genius jewel thief as he carries out a quantum measurement on a diamond without ever touching the object in question. Baffle yourself with the bizzareness of quantum tunneling, the equivalent of traveling partway up a hill, only to disappear then reappear traveling down the opposite side. With its clean, colorful layout and conversational tone, this text will hook you into the conundrum that is quantum mechanics.

  18. Charge Transport Along Phenylenevinylene Molecular Wires

    OpenAIRE

    Siebbeles, Laurens; Prins, Paulette; Grozema, Ferdinand

    2006-01-01

    Abstract A model to calculate the mobility of charges along molecular wires is presented. The model is based on the tight-binding approximation and combines a quantum mechanical description of the charge with a classical description of the structural degrees of freedom. It is demonstrated that the average mobility of charge carriers along molecular wires can be obtained by time-propagation of states which are initially localised. The model is used to calculate the mobility of charg...

  19. Coupling of individual quantum emitters to channel plasmons

    DEFF Research Database (Denmark)

    Bermúdez-Urena, E.; Gonzalez-Ballestero, C.; Geiselmann, M.

    2015-01-01

    Efficient light-matter interaction lies at the heart of many emerging technologies that seek on-chip integration of solid-state photonic systems. Plasmonic waveguides, which guide the radiation in the form of strongly confined surface plasmon-polariton modes, represent a promising solution...... the position and orientation of the quantum emitter for optimum coupling. Concomitantly with these predictions, we demonstrate experimentally that 42% of a single nitrogen-vacancy centre emission efficiently couples into the supported modes of the V-groove. This work paves the way towards practical realization...

  20. Automatic wire twister.

    Science.gov (United States)

    Smith, J F; Rodeheaver, G T; Thacker, J G; Morgan, R F; Chang, D E; Fariss, B L; Edlich, R F

    1988-06-01

    This automatic wire twister used in surgery consists of a 6-inch needle holder attached to a twisting mechanism. The major advantage of this device is that it twists wires significantly more rapidly than the conventional manual techniques. Testing has found that the ultimate force required to disrupt the wires twisted by either the automatic wire twister or manual techniques did not differ significantly and was directly related to the number of twists. The automatic wire twister reduces the time needed for wire twisting without altering the security of the twisted wire.

  1. Stretched Wire Mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Bowden, Gordon; /SLAC

    2005-09-06

    Stretched wires are beginning to play an important role in the alignment of accelerators and synchrotron light sources. Stretched wires are proposed for the alignment of the 130 meter long LCLS undulator. Wire position technology has reached sub-micron resolution yet analyses of perturbations to wire straightness are hard to find. This paper considers possible deviations of stretched wire from the simple 2-dimensional catenary form.

  2. Wire bonding in microelectronics

    CERN Document Server

    Harman, George G

    2010-01-01

    Wire Bonding in Microelectronics, Third Edition, has been thoroughly revised to help you meet the challenges of today's small-scale and fine-pitch microelectronics. This authoritative guide covers every aspect of designing, manufacturing, and evaluating wire bonds engineered with cutting-edge techniques. In addition to gaining a full grasp of bonding technology, you'll learn how to create reliable bonds at exceedingly high yields, test wire bonds, solve common bonding problems, implement molecular cleaning methods, and much more. Coverage includes: Ultrasonic bonding systems and technologies, including high-frequency systems Bonding wire metallurgy and characteristics, including copper wire Wire bond testing Gold-aluminum intermetallic compounds and other interface reactions Gold and nickel-based bond pad plating materials and problems Cleaning to improve bondability and reliability Mechanical problems in wire bonding High-yield, fine-pitch, specialized-looping, soft-substrate, and extreme-temperature wire bo...

  3. Electronic properties of quasi one-dimensional quantum wire models under equal coupling strength superpositions of Rashba and Dresselhaus spin-orbit interactions in the presence of an in-plane magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Papp, E. [Physics Department, West University of Timisoara, RO-300223, Timisoara (Romania); Micu, C.; Racolta, D. [Faculty of Science, North University of Baia Mare, RO-430122, Baia Mare (Romania)

    2013-11-13

    In this paper one deals with the theoretical derivation of energy bands and of related wavefunctions characterizing quasi 1D semiconductor heterostructures, such as InAs quantum wire models. Such models get characterized this time by equal coupling strength superpositions of Rashba and Dresselhaus spin-orbit interactions of dimensionless magnitude a under the influence of in-plane magnetic fields of magnitude B. We found that the orientations of the field can be selected by virtue of symmetry requirements. For this purpose one resorts to spin conservations, but alternative conditions providing sensible simplifications of the energy-band formula can be reasonably accounted for. Besides the wavenumber k relying on the 1D electron, one deals with the spin-like s=±1 factors in the front of the square root term of the energy. Having obtained the spinorial wavefunction, opens the way to the derivation of spin precession effects. For this purpose one resorts to the projections of the wavenumber operator on complementary spin states. Such projections are responsible for related displacements proceeding along the Ox-axis. This results in a 2D rotation matrix providing both the precession angle as well as the precession axis.

  4. Binding energy and nonlinear optical properties of an on-center hydrogenic impurity in a spherical quantum dot placed at the center of a cylindrical nano-wire: Comparison of hydrogenic donor and acceptor impurities

    Science.gov (United States)

    Safarpour, Gh.; Novzari, M.; Izadi, M. A.; Niknam, E.; Barati, M.

    2014-03-01

    The binding energies and corresponding wave functions of ground and first excited states (1s, 2p) of on-center hydrogenic donor and acceptor impurities are calculated using finite difference approximation in the effective mass framework. The on-center impurities are assumed to be in an InAs spherical quantum dot which is located at the center of a GaAs cylindrical nano-wire. To test the validity of applied method the eigenvalues of ground and first excited states are compared with reported results which have been calculated by finite element methods and it is shown that the finite difference approximation is more accurate in this particular case. In addition, the oscillator strength, linear, third-order nonlinear and total optical absorption coefficients and refractive index changes have been calculated for 1s-2p transition by means of the compact density matrix approach. The results show that presence of impurity causes a blue shift in optical spectrum which is larger for acceptor impurity. Also, the amplitude of absorption coefficient, refractive index changes and oscillator strength depend on the absence, presence and type of impurity. Moreover, it is found that the saturation condition can be tuned by type of impurity and critical incident optical intensity is enhanced in presence of acceptor impurity.

  5. Laser Wire Stripper

    Science.gov (United States)

    1983-01-01

    NASA-developed space shuttle technology is used in a laser wire stripper designed by Raytheon Company. Laser beams cut through insulation on a wire without damaging conductive metal, because laser radiation that melts plastic insulation is reflected by the metal. The laser process is fast, clean, precise and repeatable. It eliminates quality control problems and the expense of rejected wiring.

  6. Flicking-wire drag tensioner

    Science.gov (United States)

    Dassele, M. A.; Fairall, H.

    1978-01-01

    Wire-drag system improves wire profile and applies consistent drag to wire. Wire drag is continuously adjustable from zero drag to tensile strength of wire. No-sag wire drag is easier to thread than former system and requires minimal downtime for cleaning and maintenance.

  7. PS wire chamber

    CERN Multimedia

    1970-01-01

    A wire chamber used at CERN's Proton Synchrotron accelerator in the 1970s. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  8. Effect of wire shape on wire array discharge

    Energy Technology Data Exchange (ETDEWEB)

    Shimomura, N.; Tanaka, Y.; Yushita, Y.; Nagata, M. [University of Tokushima, Department of Electrical and Electronic Engineering, Tokushima (Japan); Teramoto, Y.; Katsuki, S.; Akiyama, H. [Kumamoto University, Department of Electrical and Computer Engineering, Kumamoto (Japan)

    2001-09-01

    Although considerable investigations have been reported on z-pinches to achieve nuclear fusion, little attention has been given from the point of view of how a wire array consisting of many parallel wires explodes. Instability existing in the wire array discharge has been shown. In this paper, the effect of wire shape in the wire array on unstable behavior of the wire array discharge is represented by numerical analysis. The claws on the wire formed in installation of wire may cause uniform current distribution on wire array. The effect of error of wire diameter in production is computed by Monte Carlo Method. (author)

  9. Wire + Arc Additive Manufacturing

    OpenAIRE

    Williams, Stewart W.; Martina, Filomeno; Addison, Adrian C.; Ding, Jialuo; Pardal, Goncalo; Colegrove, Paul A.

    2016-01-01

    Depositing large components (>10 kg) in titanium, aluminium, steel and other metals is possible using Wire + Arc Additive Manufacturing. This technology adopts arc welding tools and wire as feedstock for additive manufacturing purposes. High deposition rates, low material and equipment costs, and good structural integrity make Wire+Arc Additive Manufacturing a suitable candidate for replacing the current method of manufacturing from solid billets or large forgings, especially with regards to ...

  10. Charpak hemispherical wire chamber

    CERN Multimedia

    1970-01-01

    pieces. Mesures are of the largest one. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  11. Photovoltaic Wire Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will investigate a new architecture for photovoltaic devices based on nanotechnology: photovoltaic wire. The...

  12. 1998 wire development workshop proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-01

    This report consists of vugraphs of the presentations at the conference. The conference was divided into the following sessions: (1) First Generation Wire Development: Status and Issues; (2) First Generation Wire in Pre-Commercial Prototypes; (3) Second Generation Wire Development: Private Sector Progress and Issues; (4) Second Generation Wire Development: Federal Laboratories; and (5) Fundamental Research Issues for HTS Wire Development.

  13. Commercial and Industrial Wiring.

    Science.gov (United States)

    Kaltwasser, Stan; Flowers, Gary

    This module is the third in a series of three wiring publications, includes additional technical knowledge and applications required for job entry in the commercial and industrial wiring trade. The module contains 15 instructional units that cover the following topics: blueprint reading and load calculations; tools and equipment; service;…

  14. Magnetoresistance peculiarities of bismuth wires in high magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Condrea, E., E-mail: condrea@nano.asm.md [Institute of Electronic Engineering and Nanotechnologies, Academy of Science of Moldova, 2028 Chisinau, Republic of Moldova (Moldova, Republic of); International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, 51-421 Wroclaw (Poland); Gilewski, A. [International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, 51-421 Wroclaw (Poland); MagNet, 50-421 Wroclaw (Poland); Nicorici, A. [Institute of Electronic Engineering and Nanotechnologies, Academy of Science of Moldova, 2028 Chisinau, Republic of Moldova (Moldova, Republic of)

    2016-03-11

    Magnetoresistance measurements of Bi wires performed in the magnetic field oriented along the bisector axis revealed unexpected anomalous peaks in a high magnetic field far above the quantum limit of the electrons. By combining a magnetic field and an uniaxial strain, we obtained a modification of the electronic structure; as a result, the quantum limit for light and heavy electrons is changed in a different way. For the case where heavy electrons are in the quantum limit, a correlation between the exit of the lowest Landau level of light electrons and the Lifshitz transition was found. - Highlights: • Glass-coated single-crystalline Bi wires attain high limit of elastic strain of up to 3.0%. • Selective modification of the electronic structure of Bi wires is obtained by combining a high magnetic field and uniaxial strain. • The correlation between the exit of the lowest Landau level of electrons and Lifshitz transition was found.

  15. Quantum optics with quantum dots in photonic nanowires

    DEFF Research Database (Denmark)

    Claudon, Julien; Munsch, Matthieu; Bleuse, Joel

    2012-01-01

    Besides microcavities and photonic crystals, photonic nanowires have recently emerged as a novel resource for solidstate quantum optics. We will review recent studies which demonstrate an excellent control over the spontaneous emission of InAs quantum dots (QDs) embedded in single-mode Ga......As photonic wires. On the basic side, we have demonstrated a strong inhibition (x 1/16) of QD SpE in thin wires (d0.95 for d~λ/n), and polarization control in elliptical nanowires. A single QD in a photonic wire is thus an attractive system to explore the physics of the "one-dimensional atom" and build novel...

  16. Universal spin dynamics in quantum wires

    Science.gov (United States)

    Fajardo, E. A.; Zülicke, U.; Winkler, R.

    2017-10-01

    We discuss the universal spin dynamics in quasi-one-dimensional systems including the real spin in narrow-gap semiconductors like InAs and InSb, the valley pseudospin in staggered single-layer graphene, and the combination of real spin and valley pseudospin characterizing single-layer transition metal dichalcogenides (TMDCs) such as MoS2, WS2, MoS2, and WSe2. All these systems can be described by the same Dirac-like Hamiltonian. Spin-dependent observable effects in one of these systems thus have counterparts in each of the other systems. Effects discussed in more detail include equilibrium spin currents, current-induced spin polarization (Edelstein effect), and spin currents generated via adiabatic spin pumping. Our work also suggests that a long-debated spin-dependent correction to the position operator in single-band models should be absent.

  17. Ultrathin Nanocrystalline Magnetic Wires

    Directory of Open Access Journals (Sweden)

    Horia Chiriac

    2017-02-01

    Full Text Available The magnetic characteristics of FINEMET type glass-coated nanowires and submicron wires are investigated by taking into account the structural evolution induced by specific annealing all the way from a fully amorphous state to a nanocrystalline structure. The differences between the magnetic properties of these ultrathin wires and those of the thicker glass-coated microwires and “conventional” wires with similar structures have been emphasized and explained phenomenologically. The domain wall propagation in these novel nanowires and submicron wires, featuring a combination between an amorphous and a crystalline structure, has also been studied, given the recent interest in the preparation and investigation of new materials suitable for the development of domain wall logic applications.

  18. Dual wire weld feed proportioner

    Science.gov (United States)

    Nugent, R. E.

    1968-01-01

    Dual feed mechanism enables proportioning of two different weld feed wires during automated TIG welding to produce a weld alloy deposit of the desired composition. The wires are fed into the weld simultaneously. The relative feed rates of the wires and the wire diameters determine the weld deposit composition.

  19. Copper wire bonding

    CERN Document Server

    Chauhan, Preeti S; Zhong, ZhaoWei; Pecht, Michael G

    2014-01-01

    This critical volume provides an in-depth presentation of copper wire bonding technologies, processes and equipment, along with the economic benefits and risks.  Due to the increasing cost of materials used to make electronic components, the electronics industry has been rapidly moving from high cost gold to significantly lower cost copper as a wire bonding material.  However, copper wire bonding has several process and reliability concerns due to its material properties.  Copper Wire Bonding book lays out the challenges involved in replacing gold with copper as a wire bond material, and includes the bonding process changes—bond force, electric flame off, current and ultrasonic energy optimization, and bonding tools and equipment changes for first and second bond formation.  In addition, the bond–pad metallurgies and the use of bare and palladium-coated copper wires on aluminum are presented, and gold, nickel and palladium surface finishes are discussed.  The book also discusses best practices and re...

  20. Development of a Flow-Through SQUID System for Non-Destructive Evaluation of MRI Wire

    National Research Council Canada - National Science Library

    Wellstood, Frederick C

    2007-01-01

    ...) superconducting quantum interference device (SQUID) system. The ability to detect small defects in km-long sections of NbTi magnet wire could improve the production yield of high-field magnets for power and medical applications...

  1. High brightness single photon sources based on photonic wires

    DEFF Research Database (Denmark)

    Claudon, J.; Bleuse, J.; Bazin, M.

    2009-01-01

    We present a novel single-photon-source based on the emission of a semiconductor quantum dot embedded in a single-mode photonic wire. This geometry ensures a very large coupling (> 95%) of the spontaneous emission to the guided mode. Numerical simulations show that a photon collection efficiency...... of GaAs and defined by reactive-ion etching....

  2. Coupled atomic wires in a synthetic magnetic field

    Science.gov (United States)

    Budich, J. C.; Elben, A.; ŁÄ cki, M.; Sterdyniak, A.; Baranov, M. A.; Zoller, P.

    2017-04-01

    We propose and study systems of coupled atomic wires in a perpendicular synthetic magnetic field as a platform to realize exotic phases of quantum matter. This includes (fractional) quantum Hall states in arrays of many wires inspired by the pioneering work [C. L. Kane et al., Phys. Rev. Lett. 88, 036401 (2002), 10.1103/PhysRevLett.88.036401], as well as Meissner phases and vortex phases in double wires. With one continuous and one discrete spatial dimension, the proposed setup naturally complements recently realized discrete counterparts, i.e., the Harper-Hofstadter model and the two-leg flux ladder, respectively. We present both an in-depth theoretical study and a detailed experimental proposal to make the unique properties of the semicontinuous Harper-Hofstadter model accessible with cold-atom experiments. For the minimal setup of a double wire, we explore how a subwavelength spacing of the wires can be implemented. This construction increases the relevant energy scales by at least an order of magnitude compared to ordinary optical lattices, thus rendering subtle many-body phenomena such as Lifshitz transitions in Fermi gases observable in an experimentally realistic parameter regime. For arrays of many wires, we discuss the emergence of Chern bands with readily tunable flatness of the dispersion and show how fractional quantum Hall states can be stabilized in such systems. Using for the creation of optical potentials Laguerre-Gauss beams that carry orbital angular momentum, we detail how the coupled atomic wire setups can be realized in nonplanar geometries such as cylinders, disks, and tori.

  3. Wire core reactor for NTP

    Science.gov (United States)

    Harty, R. B.

    1991-01-01

    The development of the wire core system for Nuclear Thermal Propulsion (NTP) that took place from 1963 to 1965 is discussed. A wire core consists of a fuel wire with spacer wires. It's an annular flow core having a central control rod. There are actually four of these, with beryllium solid reflectors on both ends and all the way around. Much of the information on the concept is given in viewgraph form. Viewgraphs are presented on design details of the wire core, the engine design, engine weight vs. thrust, a technique used to fabricate the wire fuel element, and axial temperature distribution.

  4. Quantum contact interactions

    Indian Academy of Sciences (India)

    Abstract. The existence of several exotic phenomena, such as duality and spectral anholonomy is pointed out in one-dimensional quantum wire with a single defect. The topological structure in the spectral space which is behind these phenomena is identified.

  5. Modern wiring practice

    CERN Document Server

    Steward, W E

    2012-01-01

    Continuously in print since 1952, Modern Wiring Practice has now been fully revised to provide an up-to-date source of reference to building services design and installation in the 21st century. This compact and practical guide addresses wiring systems design and electrical installation together in one volume, creating a comprehensive overview of the whole process for contractors and architects, as well as electricians and other installation engineers. Best practice is incorporated throughout, combining theory and practice with clear and accessible explanation, all

  6. Wiring and lighting

    CERN Document Server

    Kitcher, Chris

    2013-01-01

    Wiring and Lighting provides a comprehensive guide to DIY wiring around the home. It sets out the regulations and legal requirements surrounding electrical installation work, giving clear guidelines that will enable the reader to understand what electrical work they are able to carry out, and what the testing and certification requirements are once the work is completed. Topics covered include: Different types of circuits; Types of cables and cable installation under floors and through joists; Isolating, earthing and bonding; Accessory boxes and fixings; Voltage bands; Detailed advice on safe

  7. Electric wiring domestic

    CERN Document Server

    Coker, A J

    1992-01-01

    Electric Wiring: Domestic, Tenth Edition, is a clear and reliable guide to the practical aspects of domestic electric wiring. Intended for electrical contractors, installation engineers, wiremen and students, its aim is to provide essential up to date information on modern methods and materials in a simple, clear, and concise manner. The main changes in this edition are those necessary to bring the work into line with the 16th Edition of the Regulations for Electrical Installations issued by the Institution of Electrical Engineers. The book begins by introducing the basic features of domestic

  8. Magnetoresistance peculiarities of bismuth wires in high magnetic field

    Science.gov (United States)

    Condrea, E.; Gilewski, A.; Nicorici, A.

    2016-03-01

    Magnetoresistance measurements of Bi wires performed in the magnetic field oriented along the bisector axis revealed unexpected anomalous peaks in a high magnetic field far above the quantum limit of the electrons. By combining a magnetic field and an uniaxial strain, we obtained a modification of the electronic structure; as a result, the quantum limit for light and heavy electrons is changed in a different way. For the case where heavy electrons are in the quantum limit, a correlation between the exit of the lowest Landau level of light electrons and the Lifshitz transition was found.

  9. Percutaneous Kirschner wire (K-wire) fixation for humerus shaft ...

    African Journals Online (AJOL)

    In the present study, Kirschner wires (K-wire) were used to achieve a closed intramedullary fixation of humeral shaft fractures. The objective of this study was to evaluate the efficacy of intramedullary K-wires for the treatment of humeral shaft fracture in children. Patients and Methods: This prospective study was conducted in ...

  10. Wiring for space applications program

    Science.gov (United States)

    Hammoud, Ahmad

    1994-01-01

    The insulation testing and analysis consists of: identifying and prioritizing NASA wiring requirements; selecting candidate wiring constructions; developing test matrix and formulating test program; managing, coordinating, and conducting tests; and analyzing and documenting data, establishing guidelines and recommendations.

  11. Debate: Wired versus Wireless.

    Science.gov (United States)

    Meeks, Glenn; Nair, Prakash

    2000-01-01

    Debates the issue of investing in wiring schools for desktop computer networks versus using laptops and wireless networks. Included are cost considerations and the value of technology for learning. Suggestions include using wireless networks for existing schools, hardwiring computers for new construction, and not using computers for elementary…

  12. Wired vs. Wireless.

    Science.gov (United States)

    Fielding, Randall

    2000-01-01

    Presents a debate on which technology will be in tomorrow's classrooms and the pros and cons of wiring classrooms and using a wireless network. Concluding comments address the likelihood, and desirability, of placing computers throughout the entire educational process and what types of computers and capabilities are needed. (GR)

  13. Wired to freedom

    DEFF Research Database (Denmark)

    Jepsen, Kim Sune Karrasch; Bertilsson, Margareta

    2017-01-01

    dimension of life science through a notion of public politics adopted from the political theory of John Dewey. We show how cochlear implantation engages different social imaginaries on the collective and individual levels and we suggest that users share an imaginary of being “wired to freedom” that involves...

  14. Gaseous wire detectors

    Energy Technology Data Exchange (ETDEWEB)

    Va' vra, J.

    1997-08-01

    This article represents a series of three lectures describing topics needed to understand the design of typical gaseous wire detectors used in large high energy physics experiments; including the electrostatic design, drift of electrons in the electric and magnetic field, the avalanche, signal creation, limits on the position accuracy as well as some problems one encounters in practical operations.

  15. 3D Wire 2015

    DEFF Research Database (Denmark)

    Jordi, Moréton; F, Escribano; J. L., Farias

    This document is a general report on the implementation of gamification in 3D Wire 2015 event. As the second gamification experience in this event, we have delved deeply in the previous objectives (attracting public areas less frequented exhibition in previous years and enhance networking) and have...

  16. Practical wiring in SI units

    CERN Document Server

    Miller, Henry A

    2013-01-01

    Practical Wiring, Volume 1 is a 13-chapter book that first describes some of the common hand tools used in connection with sheathed wiring. Subsequent chapters discuss the safety in wiring, cables, conductor terminations, insulating sheathed wiring, conductor sizes, and consumer's control equipments. Other chapters center on socket outlets, plugs, lighting subcircuits, lighting accessories, bells, and primary and secondary cells. This book will be very valuable to students involved in this field of interest.

  17. Wire EDM for Refractory Materials

    Science.gov (United States)

    Zellars, G. R.; Harris, F. E.; Lowell, C. E.; Pollman, W. M.; Rys, V. J.; Wills, R. J.

    1982-01-01

    In an attempt to reduce fabrication time and costs, Wire Electrical Discharge Machine (Wire EDM) method was investigated as tool for fabricating matched blade roots and disk slots. Eight high-strength nickel-base superalloys were used. Computer-controlled Wire EDM technique provided high quality surfaces with excellent dimensional tolerances. Wire EDM method offers potential for substantial reductions in fabrication costs for "hard to machine" alloys and electrically conductive materials in specific high-precision applications.

  18. Quantum well lasers

    CERN Document Server

    Zory, Jr, Peter S; Kelley, Paul

    1993-01-01

    This book provides the information necessary for the reader to achieve a thorough understanding of all aspects of QW lasers - from the basic mechanism of optical gain, through the current technolgoical state of the art, to the future technologies of quantum wires and quantum dots. In view of the growing importance of QW lasers, this book should be read by all those with an active interest in laser science and technology, from the advanced student to the experienced laser scientist.* The first comprehensive book-length treatment of quantum well lasers* Provides a detailed treatment

  19. Towards quantum information transport through a classical conductor

    Science.gov (United States)

    An, Da; Haeffner, Hartmut; Lewin-Berlin, Maya; Urban, Erik

    2017-04-01

    Establishing quantum links between separately trapped ions is a significant step towards scalable trapped ion quantum computation. Here, we present our design, simulation, and ongoing implementation of a novel surface ion trap for studying quantum correlations between separate trapping sights through an ordinary conducting wire. This is a challenging task since the thermal noise in the wire is much greater than the motional ion energy, but as long as the decoherence sources are minimized, we can achieve quantum coupling through the wire. We also include intermediate steps towards this goal, such as characterizing the stability of our novel trap, which has variable trapping height, and establishing a classical link through the wire. This technology may lead to quantum computation with mixed ion species, sympathetic cooling of ion species that cannot be co-trapped, and hybrid quantum devices that couple ion based qubits with superconducting qubits.

  20. Fulleropyrrolidine end-capped molecular wires for molecular electronics--synthesis, spectroscopic, electrochemical, and theoretical characterization

    DEFF Research Database (Denmark)

    Sørensen, Jakob Kryger; Fock, Jeppe; Pedersen, Anders Holmen

    2011-01-01

    In continuation of previous studies showing promising metal-molecule contact properties a variety of C(60) end-capped "molecular wires" for molecular electronics were prepared by variants of the Prato 1,3-dipolar cycloaddition reaction. Either benzene or fluorene was chosen as the central wire......-withdrawing ester group present. The effect of extending the p-system of the central wire from 1,4-phenylenediamine to 2,7-fluorenediamine was investigated by absorption, fluorescence, and electrochemical methods. The central wire and the C(60) end-groups were found not to electronically communicate in the ground...... state. However, the fluorescence of C(60) was quenched by charge transfer from the wire to C(60). Quantum chemical calculations predict and explain the collapse of coherent electronic transmission through one of the fulleropyrrolidine-terminated molecular wires....

  1. Obelix Wire Chamber

    CERN Multimedia

    1986-01-01

    Two wire chambers made originally for the R807 Experiment at CERN's Intersecting Storage Rings. In 1986 they were used for the PS 201 experiment (Obelix Experiment) at LEAR, the Low Energy Antiproton Ring. The group of researchers from Turin, using the chambers at that time, changed the acquisition system using for the first time 8 bit (10 bit non linear) analog to digital conversion for incoming signals from the chambers. The acquisition system was controlled by 54 CPU and 80 digital signal processors. The power required for all the electronics was 40 kW. For the period, this system was one of the most powerful on-line apparatus in the world. The Obelix Experiment was closed in 1996. To find more about how a wire chamber works, see the description for object CERN-OBJ-DE-038.

  2. Command Wire Sensor Measurements

    Science.gov (United States)

    2012-09-01

    NPS anechoic chamber is located in Spanagel Hall, Room 604. Although the chamber was built for instruction purposes only, it can be used for research...thesis is to investigate the wire scattering behavior and clutter characteristics through measurements performed in the NPS anechoic chamber. The...research has successfully resolved the various multipath components within the anechoic chamber. The transmit-receive coupling between the antennas was

  3. Wire Array Solar Cells: Fabrication and Photoelectrochemical Studies

    Science.gov (United States)

    Spurgeon, Joshua Michael

    /polymer composite films showed that their energy-conversion properties were comparable to those of an array attached to the growth substrate. High quantum efficiencies were observed relative to the packing density of the wires, particularly with illumination at high angles of incidence. The results indicate that an inexpensive, solid-state Si wire array solar cell is possible, and a plan is presented to develop one.

  4. Dual wire welding torch and method

    Science.gov (United States)

    Diez, Fernando Martinez; Stump, Kevin S.; Ludewig, Howard W.; Kilty, Alan L.; Robinson, Matthew M.; Egland, Keith M.

    2009-04-28

    A welding torch includes a nozzle with a first welding wire guide configured to orient a first welding wire in a first welding wire orientation, and a second welding wire guide configured to orient a second welding wire in a second welding wire orientation that is non-coplanar and divergent with respect to the first welding wire orientation. A method of welding includes moving a welding torch with respect to a workpiece joint to be welded. During moving the welding torch, a first welding wire is fed through a first welding wire guide defining a first welding wire orientation and a second welding wire is fed through a second welding wire guide defining a second welding wire orientation that is divergent and non-coplanar with respect to the first welding wire orientation.

  5. Efficient Quantum Information Transfer Through a Uniform Channel

    Directory of Open Access Journals (Sweden)

    Paola Verrucchi

    2011-06-01

    Full Text Available Effective quantum-state and entanglement transfer can be obtained by inducing a coherent dynamics in quantum wires with homogeneous intrawire interactions. This goal is accomplished by optimally tuning the coupling between the wire endpoints and the two qubits there attached. A general procedure to determine such value is devised, and scaling laws between the optimal coupling and the length of the wire are found. The procedure is implemented in the case of a wire consisting of a spin-1/2 XY chain: results for the time dependence of the quantities which characterize quantum-state and entanglement transfer are found of extremely good quality also for very long wires. The present approach does not require engineered intrawire interactions nor a specific initial pulse shaping, and can be applied to a vast class of quantum channels.

  6. Metering Wheel-Wire Track Wire Boom Deployment Mechanism

    Science.gov (United States)

    Granoff, Mark S.

    2014-01-01

    The NASA MMS Spin Plane Double Probe (SDP) Deployer utilizes a helical path, rotating Metering Wheel and a spring loaded Wire "Holding" Track to pay out a "fixed end" 57 meter x 1.5 mm diameter Wire Boom stored between concentric storage cylinders. Unlike rotating spool type storage devices, the storage cylinders remain stationary, and the boom wire is uncoiled along the length of the cylinder via the rotation of the Metering Wheel. This uncoiling action avoids the need for slip-ring contacts since the ends of the wire can remain stationary. Conventional fixed electrical connectors (Micro-D type) are used to terminate to operational electronics.

  7. Reduction in wire tension caused by wire clamping and wire tensioner removal: an experimental Ilizarov frame study.

    Science.gov (United States)

    La Russa, Valentina; Skallerud, Bjørn; Klaksvik, Jomar; Foss, Olav A

    2011-03-01

    The stability of an external ring fixator mainly depends on wire tension. Wire fixators should maintain the tension during both wire clamping to the ring and removal of the tensioner device. In the present study the loss in wire tension related to fixator clamping and wire tensioner removal using three different wire fixator designs was studied. The fixators were based on two different cannulated bolts and a washer. Effects from two different pretension levels in combination with three different bolt torque levels upon loss in wire tension were described. Emitted wire vibration frequency was used to assess the corresponding wire tension. Wire tension was determined after each wire fixator tightening and after the removal of the wire tensioner. Increased bolt torque led to a small decrease in tension for both pretension levels. A considerable higher tension loss was measured when removing the wire tensioner. In all cases, the combination of a new cannulated bolt and a washer maintained the highest tension.

  8. Review of wire chamber aging

    Energy Technology Data Exchange (ETDEWEB)

    Va' Vra, J.

    1986-02-01

    This paper makes an overview of the wire chamber aging problems as a function of various chamber design parameters. It emphasizes the chemistry point of view and many examples are drawn from the plasma chemistry field as a guidance for a possible effort in the wire chamber field. The paper emphasizes the necessity of variable tuning, the importance of purity of the wire chamber environment, as well as it provides a practical list of presently known recommendations. In addition, several models of the wire chamber aging are qualitatively discussed. The paper is based on a summary talk given at the Wire Chamber Aging Workshop held at LBL, Berkeley on January 16-17, 1986. Presented also at Wire Chamber Conference, Vienna, February 25-28, 1986. 74 refs., 18 figs., 11 tabs.

  9. Wiring regulations in brief

    CERN Document Server

    Tricker, Ray

    2012-01-01

    Tired of trawling through the Wiring Regs?Perplexed by Part P?Confused by cables, conductors and circuits?Then look no further! This handy guide provides an on-the-job reference source for Electricians, Designers, Service Engineers, Inspectors, Builders, Students, DIY enthusiastsTopic-based chapters link areas of working practice - such as cables, installations, testing and inspection, special locations - with the specifics of the Regulations themselves. This allows quick and easy identification of the official requirements relating to the situati

  10. Corrosion of Wires on Wooden Wire-Bound Packaging Crates

    Science.gov (United States)

    Samuel L. Zelinka; Stan Lebow

    2015-01-01

    Wire-bound packaging crates are used by the US Army to transport materials. Because these crates may be exposed to harsh environments, they are dip-treated with a wood preservative (biocide treatment). For many years, zinc-naphthenate was the most commonly used preservative for these packaging crates and few corrosion problems with the wires were observed. Recently,...

  11. Electron conductance in curved quantum structures

    DEFF Research Database (Denmark)

    Willatzen, Morten; Gravesen, Jens

    2010-01-01

    A differential-geometry analysis is employed to investigate the transmission of electrons through a curved quantum-wire structure. Although the problem is a three-dimensional spatial problem, the Schrodinger equation can be separated into three general coordinates. Hence, the proposed method...... is computationally fast and provides direct (geometrical) parameter insight as regards the determination of the electron transmission coefficient. We present, as a case study, calculations of the electron conductivity of a helically shaped quantum-wire structure and discuss the influence of the quantum...

  12. Most Wired 2006: measuring value.

    Science.gov (United States)

    Solovy, Alden

    2006-07-01

    As the Most Wired hospitals incorporate information technology into their strategic plans, they combine a"balanced scorecard"approach with classic business analytics to measure how well IT delivers on their goals. To find out which organizations made this year's 100 Most Wired list, as well as those named in other survey categories, go to the foldout section.

  13. Plasma chemistry in wire chambers

    Energy Technology Data Exchange (ETDEWEB)

    Wise, J.

    1990-05-01

    The phenomenology of wire chamber aging is discussed and fundamentals of proportional counters are presented. Free-radical polymerization and plasma polymerization are discussed. The chemistry of wire aging is reviewed. Similarities between wire chamber plasma (>1 atm dc-discharge) and low-pressure rf-discharge plasmas, which have been more widely studied, are suggested. Construction and use of a system to allow study of the plasma reactions occurring in wire chambers is reported. A proportional tube irradiated by an {sup 55}Fe source is used as a model wire chamber. Condensable species in the proportional tube effluent are concentrated in a cryotrap and analyzed by gas chromatography/mass spectrometry. Several different wire chamber gases (methane, argon/methane, ethane, argon/ethane, propane, argon/isobutane) are tested and their reaction products qualitatively identified. For all gases tested except those containing methane, use of hygroscopic filters to remove trace water and oxygen contaminants from the gas resulted in an increase in the average molecular weight of the products, consistent with results from low-pressure rf-discharge plasmas. It is suggested that because water and oxygen inhibit polymer growth in the gas phase that they may also reduce polymer deposition in proportional tubes and therefore retard wire aging processes. Mechanistic implications of the plasma reactions of hydrocarbons with oxygen are suggested. Unresolved issues in this work and proposals for further study are discussed.

  14. Cavity Mode Related Wire Breaking of the SPS Wire Scanners and Loss Measurements of Wire Materials

    CERN Document Server

    Caspers, Friedhelm; Jensen, E; Koopman, J; Malo, J F; Roncarolo, F

    2003-01-01

    During the SPS high intensity run 2002 with LHC type beam, the breaking of several of the carbon wires in the wire scanners has been observed in their parking position. The observation of large changes in the wire resistivity and thermionic electron emission clearly indicated strong RF heating that was depending on the bunch length. A subsequent analysis in the laboratory, simulating the beam by two probe antennas or by a powered stretched wire, showed two main problems: i) the housing of the wire scanner acts as a cavity with a mode spectrum starting around 350 MHz and high impedance values around 700 MHz; ii) the carbon wire used so far appears to be an excellent RF absorber and thus dissipates a significant part of the beam-induced power. Different wire materials are compared with the classical cavity mode technique for the determination of the complex permittivity in the range of 2-4 GHz. As a resonator a rectangular TE_01n type device is utilized.

  15. Cavity mode related wire breaking of the SPS Wire Scanners and loss measurements of wire materials

    CERN Document Server

    Roncarolo, Federico

    2003-01-01

    During the SPS high intensity run 2002 with LHC type beam, the breaking of several of the carbon wires in the wire scanners has been observed in their parking position. The observation of large changes in the wire resistivity and thermionic electron emission clearly indicated strong RF heating that was depending on the bunch length. A subsequent analysis in the laboratory, simulating the beam by two probe antennas or by a powered stretched wire, showed two main problems: i) the housing of the wire scanner acts as a cavity with a mode spectrum starting around 350MHz and high impedance values around 700 MHz; ii) the carbon wire used so far appears to be an excellent RF absorber and thus dissipates a significant part of the beam-induced power. Different wire materials are compared with the classical cavity mode technique for the determination of the complex permittivity in the range of 2-4 GHz. As a resonator a rectangular TE01n type device is utilized.

  16. Modeling birds on wires.

    Science.gov (United States)

    Aydoğdu, A; Frasca, P; D'Apice, C; Manzo, R; Thornton, J M; Gachomo, B; Wilson, T; Cheung, B; Tariq, U; Saidel, W; Piccoli, B

    2017-02-21

    In this paper we introduce a mathematical model to study the group dynamics of birds resting on wires. The model is agent-based and postulates attraction-repulsion forces between the interacting birds: the interactions are "topological", in the sense that they involve a given number of neighbors irrespective of their distance. The model is first mathematically analyzed and then simulated to study its main properties: we observe that the model predicts birds to be more widely spaced near the borders of each group. We compare the results from the model with experimental data, derived from the analysis of pictures of pigeons and starlings taken in New Jersey: two different image elaboration protocols allow us to establish a good agreement with the model and to quantify its main parameters. We also discuss the potential handedness of the birds, by analyzing the group organization features and the group dynamics at the arrival of new birds. Finally, we propose a more refined mathematical model that describes landing and departing birds by suitable stochastic processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Quantum Erasure: Quantum Interference Revisited

    OpenAIRE

    Walborn, Stephen P.; Cunha, Marcelo O. Terra; Pádua, Sebastião; Monken, Carlos H.

    2005-01-01

    Recent experiments in quantum optics have shed light on the foundations of quantum physics. Quantum erasers - modified quantum interference experiments - show that quantum entanglement is responsible for the complementarity principle.

  18. Topology Optimized Photonic Wire Splitters

    DEFF Research Database (Denmark)

    Frandsen, Lars Hagedorn; Borel, Peter Ingo; Jensen, Jakob Søndergaard

    2006-01-01

    Photonic wire splitters have been designed using topology optimization. The splitters have been fabricated in silicon-on-insulator material and display broadband low-loss 3dB splitting in a bandwidth larger than 100 nm.......Photonic wire splitters have been designed using topology optimization. The splitters have been fabricated in silicon-on-insulator material and display broadband low-loss 3dB splitting in a bandwidth larger than 100 nm....

  19. HTS Wire Development Workshop: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    1994-07-01

    The 1994 High-Temperature Superconducting Wire Development Workshop was held on February 16--17 at the St. Petersburg Hilton and Towers in St. Petersburg, Florida. The meeting was hosted by Florida Power Corporation and sponsored by the US Department of Energy`s Superconductivity Program for Electric Power Systems. The meeting focused on recent high-temperature superconducting wire development activities in the Department of Energy`s Superconductivity Systems program. The meeting opened with a general discussion on the needs and benefits of superconductivity from a utility perspective, the US global competitiveness position, and an outlook on the overall prospects of wire development. The meeting then focused on four important technology areas: Wire characterization: issues and needs; technology for overcoming barriers: weak links and flux pinning; manufacturing issues for long wire lengths; and physical properties of HTS coils. Following in-depth presentations, working groups were formed in each technology area to discuss the most important current research and development issues. The working groups identified research areas that have the potential for greatly enhancing the wire development effort. These areas are discussed in the summary reports from each of the working groups. This document is a compilation of the workshop proceedings including all general session presentations and summary reports from the working groups.

  20. 30 CFR 75.701-4 - Grounding wires; capacity of wires.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding wires; capacity of wires. 75.701-4... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Grounding § 75.701-4 Grounding wires; capacity of wires. Where grounding wires are used to ground metallic sheaths, armors, conduits, frames...

  1. 1 mil gold bond wire study.

    Energy Technology Data Exchange (ETDEWEB)

    Huff, Johnathon; McLean, Michael B.; Jenkins, Mark W.; Rutherford, Brian Milne

    2013-05-01

    In microcircuit fabrication, the diameter and length of a bond wire have been shown to both affect the current versus fusing time ratio of a bond wire as well as the gap length of the fused wire. This study investigated the impact of current level on the time-to-open and gap length of 1 mil by 60 mil gold bond wires. During the experiments, constant current was provided for a control set of bond wires for 250ms, 410ms and until the wire fused; non-destructively pull-tested wires for 250ms; and notched wires. The key findings were that as the current increases, the gap length increases and 73% of the bond wires will fuse at 1.8A, and 100% of the wires fuse at 1.9A within 60ms. Due to the limited scope of experiments and limited data analyzed, further investigation is encouraged to confirm these observations.

  2. Cold atoms in microscopic traps from wires to chips

    CERN Document Server

    Cassettari, D

    2000-01-01

    Ioffe-Pritchard trap. In the latter we have achieved the trapping parameters required in the experiments with Bose-Einstein condensates with much reduced power consumption. In a second time we have replaced the free standing wires with an atom chip, which we have used to compress the atomic cloud in potentials with trap frequencies above 100 kHz and ground state sizes below 100 nm. Such potentials are especially interesting for quantum information proposals of performing quantum gate operations with controlled collisions between trapped atoms. Finally, by combining two wire guides we have experimentally realized an innovative kind of beam splitter for guided atoms. We have investigated the splitting potential generated by a Y-shaped wire which has one input, i.e. the central arm of the Y, and two outputs corresponding to the left and right arms of the Y. By tuning the current ratio in the two outputs we have observed atoms switching from left to right as well as symmetric splitting. This and other similar des...

  3. Wire chambers revisited.

    Science.gov (United States)

    Ott, R J

    1993-04-01

    Detectors used for radioisotope imaging have, historically, been based on scintillating crystal/photomultiplier combinations in various forms. From the rectilinear scanner through to modern gamma cameras and positron cameras, the basic technology has remained much the same. Efforts to overcome the limitations of this form of technology have foundered on the inability to reproduce the required sensitivity, spatial resolution and sensitive area at acceptable cost. Multiwire proportional chambers (MWPCs) have long been used as position-sensitive charged particle detectors in nuclear and high-energy physics. MWPCs are large-area gas-filled ionisation chambers in which large arrays of fine wires are used to measure the position of ionisation produced in the gas by the passage of charged particles. The important properties of MWPCs are high-spatial-resolution, large-area, high-count-rate performance at low cost. For research applications, detectors several metres square have been built and small-area detectors have a charged particle resolution of 0.4 mm at a count rate of several million per second. Modification is required to MWPCs for nuclear medicine imaging. As gamma rays or X-rays cannot be detected directly, they must be converted into photo- or Compton scatter electrons. Photon-electron conversion requires the use of high atomic number materials in the body of the chamber. Pressurised xenon is the most useful form of "gas only" photon-electron convertor and has been used successfully in a gamma camera for the detection of gamma rays at energies below 100 keV. This camera has been developed specifically for high-count-rate first-pass cardiac imaging. This high-pressure xenon gas MWPC is the key to a highly competitive system which can outperform scintillator-based systems. The count rate performance is close to a million counts per second and the intrinsic spatial resolution is better than the best scintillator-based camera. The MWPC camera produces quantitative

  4. An asymptotic solution of the Schroedinger equation for the elliptic wire in the magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Bejenari, I; Kantser, V [Institute of Electronic Engineering and Industrial Technologies, Academiei str., 3/3, MD2028 Chisinau (Moldova, Republic of)], E-mail: bejenari@iieti.asm.md

    2008-10-03

    An asymptotic solution of the Schroedinger equation with non-separable variables is obtained for a particle confined to an infinite elliptic cylinder potential well under an applied uniform longitudinal magnetic field. Using the standard-problem method, dimension-quantized eigenvalues have been calculated when the magnetic length is large enough in comparison with the half of the distance between the boundary ellipse focuses. In semi-classical approximation, the confined electron (hole) states are divided into the boundary states (BS), ring states (RS), hyperbolic caustic states (HCS) and harmonic oscillator states (HOS). For large angular momentum quantum numbers and small radial quantum numbers, the BS and RS are grouped into the 'whispering gallery' mode. They associate with particles moving along the wire cross section boundary. The motion is limited from the wire core by the elliptic caustic. Consisting of the HCS and HOS, the 'jumping ball' modes correspond to the states of particle moving along a wire diameter when the angular momentum quantum number is much less than the radial quantum number. In this case, the motion is restricted by the hyperbolic caustics and two boundary ellipse arcs. For excited hole states in a Bi wire, the energy spectrum and space probability distribution are analyzed.

  5. InP based lasers and optical amplifiers with wire-/dot-like active regions

    DEFF Research Database (Denmark)

    Reithmaier, J. P.; Somers, A.; Deubert, S.

    2005-01-01

    Long wavelength lasers and semiconductor optical amplifiers based on InAs quantum wire/dot-like active regions were developed on InP substrates dedicated to cover the extended telecommunication wavelength range between 1.4 - 1.65 mm. In a brief overview different technological approaches...

  6. Plasma arc torch with coaxial wire feed

    Science.gov (United States)

    Hooper, Frederick M

    2002-01-01

    A plasma arc welding apparatus having a coaxial wire feed. The apparatus includes a plasma arc welding torch, a wire guide disposed coaxially inside of the plasma arc welding torch, and a hollow non-consumable electrode. The coaxial wire guide feeds non-electrified filler wire through the tip of the hollow non-consumable electrode during plasma arc welding. Non-electrified filler wires as small as 0.010 inches can be used. This invention allows precision control of the positioning and feeding of the filler wire during plasma arc welding. Since the non-electrified filler wire is fed coaxially through the center of the plasma arc torch's electrode and nozzle, the wire is automatically aimed at the optimum point in the weld zone. Therefore, there is no need for additional equipment to position and feed the filler wire from the side before or during welding.

  7. Ocular dangers of fencing wire.

    Science.gov (United States)

    McAllum, P; Barnes, R; Dickson, J

    2001-07-27

    To invesitgate the incidence and severity of penetrating eye injuries caused by fencing wire in the Waikato region. We reviewed the case notes for all penetrating eye injuries treated at Waikato Hospital during the past six years. Parameters recorded were patient age and sex, mechanism of injury, initial visual acuity, characteristics of injury, surgery performed and final visual outcome. The incidence of penetrating eye injuries in the Waikato region was 3.8 per 100,000 per year, based on an estimated catchment population of 350,000. We found fencing wire to be the third most common cause of penetrating eye injury, accounting for 8.8% of injuries, behind motor vehicle accidents and hammering which accounted for 26.3% and 20.0% of injuries, respectively. The fencing wire injuries involved men exclusively, with an average age of 41.7 years. Fencing wire injuries had worse presenting visual acuity than other injuries, involved the posterior segment of the eye more frequently and were more likely to develop bacterial endophthalmitis. They also underwent more surgical procedures and were more commonly associated with a poor visual outcome. Fencing wire is an important cause of visual loss in the Waikato region. We hope to raise awareness of its potential ocular dangers and to promote the use of appropriate eye protection.

  8. Quantum computing

    OpenAIRE

    Li, Shu-shen; Long, Gui-Lu; Bai, Feng-Shan; Feng, Song-Lin; Zheng, Hou-Zhi

    2001-01-01

    Quantum computing is a quickly growing research field. This article introduces the basic concepts of quantum computing, recent developments in quantum searching, and decoherence in a possible quantum dot realization.

  9. Weyl fermions in cylindrical wires

    Science.gov (United States)

    Erementchouk, Mikhail; Mazumder, Pinaki

    2018-01-01

    The key feature of Weyl semimetals (WSMs) is the presence of topologically protected Dirac cones in a three-dimensional material. We consider the effect of restricting geometry on the spectrum of excitations in WSMs using as a model a cylindrical WSM wire. For the full manifold of hard boundary conditions, we derive the general form of the dispersion equation relating the energy of the excitations and their momentum along the wire. We show that only the special class of boundary conditions, corresponding to decoupled helicities or, equivalently, to pinned directions of the electron spin on the surface, support massless excitations. For a general boundary condition, these excitations acquire mass inversely proportional to the radius of the wire. This demonstrates that boundary phenomena may play a crucial role in formation of excitations in WSM based structures.

  10. Performance of Continuous Quantum Thermal Devices Indirectly Connected to Environments

    Directory of Open Access Journals (Sweden)

    J. Onam González

    2016-04-01

    Full Text Available A general quantum thermodynamics network is composed of thermal devices connected to environments through quantum wires. The coupling between the devices and the wires may introduce additional decay channels which modify the system performance with respect to the directly-coupled device. We analyze this effect in a quantum three-level device connected to a heat bath or to a work source through a two-level wire. The steady state heat currents are decomposed into the contributions of the set of simple circuits in the graph representing the master equation. Each circuit is associated with a mechanism in the device operation and the system performance can be described by a small number of circuit representatives of those mechanisms. Although in the limit of weak coupling between the device and the wire the new irreversible contributions can become small, they prevent the system from reaching the Carnot efficiency.

  11. Boundary scattering in wet-etched InAs/GaSb heterostructure wires: with and without magnetic field

    Science.gov (United States)

    Rahman, F.; Thornton, T. J.; Gallagher, B. L.; Stradling, R. A.

    1999-05-01

    We report the observation of boundary scattering in damage-free wires made from InAs/GaSb quantum wells. Fabrication of very long wires has enabled us to observe boundary scattering contribution to the resistivity of these wires both with and without a magnetic field. A very well-defined region of suppression of both field-induced and zero-field boundary scattering was observed. These effects were seen to become more pronounced as the width of the wires was reduced. Differences from boundary scattering in GaAs/AlGaAs heterostructure wires are pointed out. Results of a study of the dependence of boundary scattering on temperature are also described.

  12. Quantum Distinction: Quantum Distinctiones!

    OpenAIRE

    Zeps, Dainis

    2009-01-01

    10 pages; How many distinctions, in Latin, quantum distinctiones. We suggest approach of anthropic principle based on anthropic reference system which should be applied equally both in theoretical physics and in mathematics. We come to principle that within reference system of life subject of mathematics (that of thinking) should be equated with subject of physics (that of nature). For this reason we enter notions of series of distinctions, quantum distinction, and argue that quantum distinct...

  13. Subchannel Analysis of Wire Wrapped SCWR Assembly

    National Research Council Canada - National Science Library

    Shan, Jianqiang; Wang, Henan; Liu, Wei; Song, Linxing; Chen, Xuanxiang; Jiang, Yang

    2014-01-01

    .... The HPLWR wire wrapped assembly was analyzed. The results show that: (1) the assembly with wire wrap can obtain a more uniform coolant temperature profile than the grid spaced assembly, which will result in a lower peak cladding temperature; (2...

  14. Signal shapes in a TPC wire chamber

    Science.gov (United States)

    Rossegger, S.; Riegler, W.

    2010-11-01

    We study signal shapes in Multi Wire Proportional Chambers (MWPCs) and the influence of the electron distribution around the wire on the ion tail characteristics. Simulations of the ion tail for two different geometries, different voltages and therefore gas gains were performed. These simulations are compared to measurements carried out with the ALICE TPC wire chambers for a Ne/CO 2/N 2 gas mixture, which allows to extract the avalanche spread around the anode wires of the MWPC.

  15. Towards Unconventional Applications of Wire Bonding

    OpenAIRE

    Schröder, Stephan

    2018-01-01

    This thesis presents novel heterogeneous integration approaches of wire materials to fabricated and package MEMS devices by exploring unconventional applications of wire bonding technology. Wire bonding, traditionally endemic in the realm of device packaging to establish electrical die-to-package interconnections, is an attractive back-end technology, offering promising features, such as high throughput, flexibility and placement accuracy. Exploiting the advantages of state-of-the-art wire bo...

  16. Novel Wiring Technologies for Aerospace Applications

    Science.gov (United States)

    Gibson, Tracy L.; Parrish, Lewis M.

    2014-01-01

    Because wire failure in aerospace vehicles could be catastrophic, smart wiring capabilities have been critical for NASA. Through the years, researchers at Kennedy Space Center (KSC) have developed technologies, expertise, and research facilities to meet this need. In addition to aerospace applications, NASA has applied its knowledge of smart wiring, including self-healing materials, to serve the aviation industry. This webinar will discuss the development efforts of several wiring technologies at KSC and provide insight into both current and future research objectives.

  17. Electron transport in stretched monoatomic gold wires.

    Science.gov (United States)

    Grigoriev, A; Skorodumova, N V; Simak, S I; Wendin, G; Johansson, B; Ahuja, R

    2006-12-08

    The conductance of monoatomic gold wires containing 3-7 gold atoms has been obtained from ab initio calculations. The transmission is found to vary significantly depending on the wire stretching and the number of incorporated atoms. Such oscillations are determined by the electronic structure of the one-dimensional (1D) part of the wire between the contacts. Our results indicate that the conductivity of 1D wires can be suppressed without breaking the contact.

  18. Detection of a buried wire with two resistively loaded wire antennas

    NARCIS (Netherlands)

    Vossen, S.H.J.A.; Tijhuis, A.G.; Lepelaars, E.S.A.M.; Zwamborn, A.P.M.

    2002-01-01

    The use of two identical straight thin-wire antennas for the detection of a buried wire is analyzed with the aid of numerical calculations. The buried wire is located below an interface between two homogeneous half-spaces. The detection setup, which is formed by a transmitting and a receiving wire,

  19. One century of Kirschner wires and Kirschner wire insertion techniques : A historical review

    NARCIS (Netherlands)

    Franssen, Bas B. G. M.; Schuurman, Arnold H.; Van der Molen, Aebele Mink; Kon, Moshe

    A century ago, in 1909, Martin Kirschner (1879-942) introduced a smooth pin, presently known as the Kirschner wire (K-wire). The K-wire was initiallly used for skeletal traction and is now currently used for many different goals. The development of the K-wire and its insertion devices were mainly

  20. Home and School Technology: Wired versus Wireless.

    Science.gov (United States)

    Van Horn, Royal

    2001-01-01

    Presents results of informal research on smart homes and appliances, structured home wiring, whole-house audio/video distribution, hybrid cable, and wireless networks. Computer network wiring is tricky to install unless all-in-one jacketed cable is used. Wireless phones help installers avoid pre-wiring problems in homes and schools. (MLH)

  1. Electrochemistry of surface wired cytochrome c and ...

    Indian Academy of Sciences (India)

    Pyrazine unit in the mixed self-assembly promotes the electron transfer in the redox reaction of surface wired Cyt-c. Cyt-c wired on the mixed self-assembly has been used for the amperometric sensing of superoxide. The enzymatically generated superoxide has been successfully detected using the Cyt-c wired electrode.

  2. 49 CFR 393.28 - Wiring systems.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Wiring systems. 393.28 Section 393.28 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER SAFETY... NECESSARY FOR SAFE OPERATION Lamps, Reflective Devices, and Electrical Wiring § 393.28 Wiring systems...

  3. Customised 2G HTS wire for applications

    Science.gov (United States)

    Samoilenkov, S.; Molodyk, A.; Lee, S.; Petrykin, V.; Kalitka, V.; Martynova, I.; Makarevich, A.; Markelov, A.; Moyzykh, M.; Blednov, A.

    2016-02-01

    Reproducibility of superconducting properties and suitability for specific applications by means of customised finish are two important attributes required from commercial 2G HTS wire. This paper reviews the consistent performance of SuperOx production 2G HTS wire and describes two novel customisation options: surround polyimide varnish insulation and composite bulk materials assembled with 2G HTS wires soldered together.

  4. Emittance growth due to Tevatron flying wires

    Energy Technology Data Exchange (ETDEWEB)

    Syphers, M; Eddy, Nathan

    2004-06-01

    During Tevatron injection, Flying Wires have been used to measure the transverse beam size after each transfer from the Main Injector in order to deduce the transverse emittances of the proton and antiproton beams. This amounts to 36 + 9 = 45 flies of each of 3 wire systems, with an individual wire passing through each beam bunch twice during a single ''fly''. below they estimate the emittance growth induced by the interaction of the wires with the particles during these measurements. Changes of emittance from Flying Wire measurements conducted during three recent stores are compared with the estimations.

  5. Plasma formation in metallic wire Z pinches

    Science.gov (United States)

    Chittenden; Lebedev; Ruiz-Camacho; Beg; Bland; Jennings; Bell; Haines; Pikuz; Shelkovenko; Hammer

    2000-04-01

    Plasma formation in metallic wire Z pinches is modeled using a two-dimensional resistive magnetohydrodynamics code. Modified Thomas-Fermi equations of state and dense plasma transport coefficients allow the phase transitions from solid to plasma to be approximated. Results indicate the persistence of a two-component structure with a cold, dense core embedded within a much hotter, low density, m=0 unstable corona. Extensive benchmark testing against data from a number of single-wire experiments is presented. Artificial laser schlieren and x-ray back-lighting images generated from the code data are compared directly to experimental results. The results were found to be insensitive to inaccuracies in the equations of state and transport coefficients. Simulations of individual wires in a wire array show different behavior to that observed experimentally due to the absence of three-dimensional effects. Simulations with similar conditions to wires in an array show a general trend in the plasma structure at start of implosion from discrete wires with large m=0 perturbation amplitudes to partially merged wires with smaller perturbation amplitudes as the number of wires is increased. Results for a wire number scan with aluminum wire arrays on the SATURN generator suggest that the observed sharp transition to high x-ray power at around 40 wires corresponds to a sharp decrease in m=0 perturbation amplitude and hence a sharp decrease in the seed perturbation for the Rayleigh-Taylor instability.

  6. Slice of LHC dipole wiring

    CERN Multimedia

    Dipole model slice made in 1994 by Ansaldo. The high magnetic fields needed for guiding particles around the Large Hadron Collider (LHC) ring are created by passing 12’500 amps of current through coils of superconducting wiring. At very low temperatures, superconductors have no electrical resistance and therefore no power loss. The LHC is the largest superconducting installation ever built. The magnetic field must also be extremely uniform. This means the current flowing in the coils has to be very precisely controlled. Indeed, nowhere before has such precision been achieved at such high currents. 50’000 tonnes of steel sheets are used to make the magnet yokes that keep the wiring firmly in place. The yokes constitute approximately 80% of the accelerator's weight and, placed side by side, stretch over 20 km!

  7. Sintered wire cesium dispenser photocathode

    Science.gov (United States)

    Montgomery, Eric J; Ives, R. Lawrence; Falce, Louis R

    2014-03-04

    A photoelectric cathode has a work function lowering material such as cesium placed into an enclosure which couples a thermal energy from a heater to the work function lowering material. The enclosure directs the work function lowering material in vapor form through a low diffusion layer, through a free space layer, and through a uniform porosity layer, one side of which also forms a photoelectric cathode surface. The low diffusion layer may be formed from sintered powdered metal, such as tungsten, and the uniform porosity layer may be formed from wires which are sintered together to form pores between the wires which are continuous from the a back surface to a front surface which is also the photoelectric surface.

  8. Genetic Optimization of Wire Antennas

    Directory of Open Access Journals (Sweden)

    Z. Raida

    1998-09-01

    Full Text Available The presented submission describes how genetic algorithms can be applied to the optimization and design of wire antennas. The proposed optimization method is easily programmable and well understandable on one hand, but relatively slowly converging and depending on the parameters of the genetic algorithms on the other hand. The disadvantages of the method are deeply discussed and their elimination is discussed in the paper.

  9. Quantum Multiverses

    OpenAIRE

    Hartle, James B.

    2018-01-01

    A quantum theory of the universe consists of a theory of its quantum dynamics and a theory of its quantum state The theory predicts quantum multiverses in the form of decoherent sets of alternative histories describing the evolution of the universe's spacetime geometry and matter content. These consequences follow: (a) The universe generally exhibits different quantum multiverses at different levels and kinds of coarse graining. (b) Quantum multiverses are not a choice or an assumption but ar...

  10. Quantum computing

    OpenAIRE

    Traub, Joseph F.

    2014-01-01

    The aim of this thesis was to explain what quantum computing is. The information for the thesis was gathered from books, scientific publications, and news articles. The analysis of the information revealed that quantum computing can be broken down to three areas: theories behind quantum computing explaining the structure of a quantum computer, known quantum algorithms, and the actual physical realizations of a quantum computer. The thesis reveals that moving from classical memor...

  11. Nonlinear Dynamics In Quantum Physics -- Quantum Chaos and Quantum Instantons

    OpenAIRE

    Kröger, H.

    2003-01-01

    We discuss the recently proposed quantum action - its interpretation, its motivation, its mathematical properties and its use in physics: quantum mechanical tunneling, quantum instantons and quantum chaos.

  12. Magnetoconductivity of quantum wires with elastic and inelastic scattering

    DEFF Research Database (Denmark)

    Bruus, Henrik; Flensberg, Karsten; Smith

    1993-01-01

    function describing the occupation of these single-particle states satisfies a Boltzmann equation, which may be solved exactly in the case of impurity scattering. In the case where the electrons scatter against both phonons and impurities we solve numerically—and in certain limits analytically—the integral...

  13. "Cut wires grating – single longitudinal wire" planar metastructure to achieve microwave magnetic resonance in a single wire

    Directory of Open Access Journals (Sweden)

    G. Kraftmakher

    2012-09-01

    Full Text Available Here we present metastructures containing cut-wire grating and a single longitudinal cut-wire orthogonal to grating’s wires. Experimental investigations at microwaves show these structures can provide strong magnetic resonant response of a single nonmagnetic cut-wire in dependence on configuration and sizes in the case when metastructures are oriented along the direction of wave propagation and cut-wires of grating are parallel to the electric field of a plane electromagnetic wave. It is suggested a concept of magnetic response based on antiparallel resonant currents excited by magnetic field of surface polaritons in many spatial LC-circuits created from cut-wire pairs of a grating and section of longitudinal cut-wire. Three separately observed resonant effects connected with grating, LC-circuits and with longitudinal cut-wire have been identified applying measurements in waveguides, cutoff waveguides and free space. To tune and mark resonance split cut-wires are loaded with varactor diodes.

  14. A Vibrating Wire System For Quadrupole Fiducialization

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, Zachary

    2010-12-13

    A vibrating wire system is being developed to fiducialize the quadrupoles between undulator segments in the LCLS. This note provides a detailed analysis of the system. The LCLS will have quadrupoles between the undulator segments to keep the electron beam focused. If the quadrupoles are not centered on the beam axis, the beam will receive transverse kicks, causing it to deviate from the undulator axis. Beam based alignment will be used to move the quadrupoles onto a straight line, but an initial, conventional alignment must place the quadrupole centers on a straight line to 100 {micro}m. In the fiducialization step of the initial alignment, the position of the center of the quadrupole is measured relative to tooling balls on the outside of the quadrupole. The alignment crews then use the tooling balls to place the magnet in the tunnel. The required error on the location of the quadrupole center relative to the tooling balls must be less than 25 {micro}m. In this note, we analyze a system under construction for the quadrupole fiducialization. The system uses the vibrating wire technique to position a wire onto the quadrupole magnetic axis. The wire position is then related to tooling balls using wire position detectors. The tooling balls on the wire position detectors are finally related to tooling balls on the quadrupole to perform the fiducialization. The total 25 {micro}m fiducialization error must be divided between these three steps. The wire must be positioned onto the quadrupole magnetic axis to within 10 {micro}m, the wire position must be measured relative to tooling balls on the wire position detectors to within 15 {micro}m, and tooling balls on the wire position detectors must be related to tooling balls on the quadrupole to within 10 {micro}m. The techniques used in these three steps will be discussed. The note begins by discussing various quadrupole fiducialization techniques used in the past and discusses why the vibrating wire technique is our method

  15. Phosphorus in antique iron music wire.

    Science.gov (United States)

    Goodway, M

    1987-05-22

    Harpsichords and other wire-strung musical instruments were made with longer strings about the beginning of the 17th century. This change required stronger music wire. Although these changes coincided with the introduction of the first mass-produced steel (iron alloyed with carbon), carbon was not found in samples of antique iron harpsichord wire. The wire contained an amount of phosphorus sufficient to have impeded its conversion to steel, and may have been drawn from iron rejected for this purpose. The method used to select pig iron for wire drawing ensured the highest possible phosphorus content at a time when its presence in iron was unsuspected. Phosphorus as an alloying element has had the reputation for making steel brittle when worked cold. Nevertheless, in replicating the antique wire, it was found that lowcarbon iron that contained 0.16 percent phosphorus was easily drawn to appropriate gauges and strengths for restringing antique harpsichords.

  16. Electromagnetic Behaviour of Metallic Wire Structures

    CERN Document Server

    Chui, S T

    2013-01-01

    Despite the recent development and interest in the photonics of metallic wire structures, the relatively simple concepts and physics often remain obscured or poorly explained to those who do not specialize in the field. Electromagnetic Behaviour of Metallic Wire Structures provides a clear and coherent guide to understanding these phenomena without excessive numerical calculations.   Including both background material and detailed derivations of the various different formulae applied, Electromagnetic Behaviour of Metallic Wire Structures describes how to extend basic circuit theory relating to voltages, currents, and resistances of metallic wire networks to include situations where the currents are no longer spatially uniform along the wire. This lays a foundation for a deeper understanding of the many new phenomena observed in meta-electromagnetic materials.   Examples of applications are included to support this new approach making Electromagnetic Behaviour of Metallic Wire Structures a comprehensive and ...

  17. IEE wiring regulations explained and illustrated

    CERN Document Server

    Scaddan, Brian

    2013-01-01

    The IEE Wiring Regulations Explained and Illustrated, Second Edition discusses the recommendations of the IEE Regulations for the Electrical Equipment of Buildings for the safe selection or erection of wiring installations. The book emphasizes earthing, bonding, protection, and circuit design of electrical wirings. The text reviews the fundamental requirements for safety, earthing systems, the earth fault loop impedance, and supplementary bonding. The book also describes the different types of protection, such as protection against mechanical damage, overcurrent, under voltage (which prevents

  18. Radiofrequency Wire Recanalization of Chronically Thrombosed TIPS

    Energy Technology Data Exchange (ETDEWEB)

    Majdalany, Bill S., E-mail: bmajdala@med.umich.edu [University of Michigan Health System, Division of Interventional Radiology, Department of Radiology (United States); Elliott, Eric D., E-mail: eric.elliott@osumc.edu [The Ohio State University Wexner Medical Center, Division of Interventional Radiology, Department of Radiology (United States); Michaels, Anthony J., E-mail: Anthony.michaels@osumc.edu; Hanje, A. James, E-mail: James.Hanje@osumc.edu [The Ohio State University Wexner Medical Center, Division of Gastroenterology and Hepatology, Department of Medicine (United States); Saad, Wael E. A., E-mail: wsaad@med.umich.edu [University of Michigan Health System, Division of Interventional Radiology, Department of Radiology (United States)

    2016-07-15

    Radiofrequency (RF) guide wires have been applied to cardiac interventions, recanalization of central venous thromboses, and to cross biliary occlusions. Herein, the use of a RF wire technique to revise chronically occluded transjugular intrahepatic portosystemic shunts (TIPS) is described. In both cases, conventional TIPS revision techniques failed to revise the chronically thrombosed TIPS. RF wire recanalization was successfully performed through each of the chronically thrombosed TIPS, demonstrating initial safety and feasibility in this application.

  19. NEW DIRECTIONS IN THE ROLLED WIRE DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    A. V. Vedeneev

    2004-01-01

    Full Text Available Analysis of the world practice and comparison with the competitors data shows, that for keeping up of RUP “BMZ'' competitiveness it is necessary to carry out works in directions of perfection of the steel wire cord production technology, development of steel wire cord, development of the breaker constructions with the high infiltration of rubber of wire with superstandard diameter and etc.

  20. Experimental setup to detect superconducting wire motion

    OpenAIRE

    K. Ruwali; A. Yamanaka; Y. Teramoto; K. Nakanishi; K. Hosoyama

    2009-01-01

    An experimental setup was designed and fabricated to study superconducting wire motion under the influence of electromagnetic force. Experiments were conducted at 4.2 K by varying the experimental conditions such as the tension to the superconducting wire and different insulating materials at the interface of the superconducting wire and head part. The insulating materials used in the experiments were polyimide film and a high strength polyethylene fiber cloth, Dyneema. Details of the experim...

  1. Minimisation of the wire position uncertainties of the new CERN vacuum wire scanner

    CERN Document Server

    AUTHOR|(CDS)2069346; Barjau Condomines, A

    In the next years the luminosity of the LHC will be significantly increased. This will require a much higher accuracy of beam profile measurement than actually achievable by the current wire scanner. The new fast wire scanner is foreseen to measure small emittance beams throughout the LHC injector chain, which demands a wire travelling speed up to 20 ms-1 and position measurement accuracy of the order of a few microns. The vibrations of the mechanical parts of the system, and particularly the vibrations of the thin carbon wire, were identified as the major error sources of wire position uncertainty. Therefore the understanding of the wire vibrations is a high priority for the design and operation of the new device. This document presents the work performed to understand the main causes of the wire vibrations observed in one of the existing wire scanner and the new proposed design.

  2. Aircraft Wiring Support Equipment Integration Laboratory (AWSEIL)

    Data.gov (United States)

    Federal Laboratory Consortium — Purpose:The Aircraft Wiring Support Equipment Integration Laboratory (AWSEIL) provides a variety of research, design engineering and prototype fabrication services...

  3. submitter Dynamical Models of a Wire Scanner

    CERN Document Server

    Barjau, Ana; Dehning, Bernd

    2016-01-01

    The accuracy of the beam profile measurements achievable by the current wire scanners at CERN is limited by the vibrations of their mechanical parts. In particular, the vibrations of the carbon wire represent the major source of wire position uncertainty which limits the beam profile measurement accuracy. In the coming years, due to the Large Hadron Collider (LHC) luminosity upgrade, a wire traveling speed up to 20 $m s^{−1}$ and a position measurement accuracy of the order of 1 μm will be required. A new wire scanner design based on the understanding of the wire vibration origin is therefore needed. We present the models developed to understand the main causes of the wire vibrations observed in an existing wire scanner. The development and tuning of those models are based on measurements and tests performed on that CERN proton synchrotron (PS) scanner. The final model for the (wire + fork) system has six degrees-of-freedom (DOF). The wire equations contain three different excitation terms: inertia...

  4. Quantum radar

    CERN Document Server

    Lanzagorta, Marco

    2011-01-01

    This book offers a concise review of quantum radar theory. Our approach is pedagogical, making emphasis on the physics behind the operation of a hypothetical quantum radar. We concentrate our discussion on the two major models proposed to date: interferometric quantum radar and quantum illumination. In addition, this book offers some new results, including an analytical study of quantum interferometry in the X-band radar region with a variety of atmospheric conditions, a derivation of a quantum radar equation, and a discussion of quantum radar jamming.This book assumes the reader is familiar w

  5. FE modeling of Cu wire bond process and reliability

    NARCIS (Netherlands)

    Yuan, C.A.; Weltevreden, E.R.; Akker, P. van den; Kregting, R.; Vreugd, J. de; Zhang, G.Q.

    2011-01-01

    Copper based wire bonding technology is widely accepted by electronic packaging industry due to the world-wide cost reduction actions (compared to gold wire bond). However, the mechanical characterization of copper wire differs from the gold wire; hence the new wire bond process setting and new bond

  6. THERMO-MECHANICALLY PROCESSED ROLLED WIRE FOR HIGH-STRENGTH ON-BOARD WIRE

    Directory of Open Access Journals (Sweden)

    V. A. Lutsenko

    2011-01-01

    Full Text Available It is shown that at twisting of wire of diameter 1,83 mm, produced by direct wire drawing of thermomechanically processed rolled wire of diameter 5,5 mm of steel 90, metal stratification is completely eliminated at decrease of carbon, manganese and an additional alloying of chrome.

  7. Finite element analysis on the wire breaking rule of 1×7IWS steel wire rope

    Directory of Open Access Journals (Sweden)

    Wenzheng Du

    2017-01-01

    Full Text Available Taking the wire rope of 1×7+IWS structure as the research object, the influences of the number of broken wires on the stress distribution under the same axial load were simulated and analysed, and it also explored the rule of wire breaking of steel wire ropes. Based on the SolidWorks software, the three-dimensional model of the wire rope was established. Importing the model into the ABAQUS, the finite element model of the steel wire rope was established. Firstly 5000 N axial tension was placed on the rope, the stress distribution was simulated and analysed, and the steel wire with the largest stress distribution was found out. Then one steel wire was truncated with the load unchanged, and the finite element simulation was carried out again, and repeated the steps several times. The results show that, with the increase of the number of broken wires, the Von-Mises stress of the wire rope increases sharply, and the stress distribution is concentrated on the rest of the unbroken wires, which brings great challenges to the safety of the wire rope.

  8. Effect of a strain on the magnetotransport properties of Bi wires

    Science.gov (United States)

    Condrea, E.; Gilewski, A.; Muntyanu, F.

    2017-08-01

    Measurements of the longitudinal resistance and Seebeck coefficient of Bi wires in a high magnetic field have revealed some anomalies in a magnetic field far above the quantum limit of the electrons; the most prominent feature is a sharp peak of magnetoresistance at 33 T. The observed correlation between a simultaneous shift of the position of the anomaly and the quantum limit of light electrons in a magnetic field during modification of the electronic structure under strain suggests that the unidentified peak can be attributed to the complex structure of the lowest Landau level of light electrons occurring in high magnetic fields.

  9. Quantum phase fluctuations and density of states in superconducting nanowires

    Science.gov (United States)

    Radkevich, Alexey; Semenov, Andrew G.; Zaikin, Andrei D.

    2017-08-01

    We argue that quantum fluctuations of the phase of the order parameter may strongly affect the electron density of states (DOS) in ultrathin superconducting wires. We demonstrate that the effect of such fluctuations is equivalent to that of a quantum dissipative environment formed by soundlike plasma modes propagating along the wire. We derive a nonperturbative expression for the local electron DOS in superconducting nanowires which fully accounts for quantum phase fluctuations. At any nonzero temperature these fluctuations smear out the square-root singularity in DOS near the superconducting gap and generate quasiparticle states at subgap energies. Furthermore, at sufficiently large values of the wire impedance this singularity is suppressed down to T =0 in which case DOS tends to zero at subgap energies and exhibits the power-law behavior above the gap. Our predictions can be directly tested in tunneling experiments with superconducting nanowires.

  10. Quantum CPU and Quantum Simulating

    OpenAIRE

    Wang, An Min

    1999-01-01

    Making use of an universal quantum network or QCPU proposed by me [6], some special quantum networks for simulating some quantum systems are given out. Specially, it is obtained that the quantum network for the time evolution operator which can simulate, in general, Schr\\"odinger equation.

  11. Quantum Computer Games: Quantum Minesweeper

    Science.gov (United States)

    Gordon, Michal; Gordon, Goren

    2010-01-01

    The computer game of quantum minesweeper is introduced as a quantum extension of the well-known classical minesweeper. Its main objective is to teach the unique concepts of quantum mechanics in a fun way. Quantum minesweeper demonstrates the effects of superposition, entanglement and their non-local characteristics. While in the classical…

  12. The Eulerian buckling test for orthodontic wires.

    Science.gov (United States)

    De Santis, R; Dolci, F; Laino, A; Martina, R; Ambrosio, L; Nicolais, L

    2008-04-01

    Orthodontic treatment is mainly dependent on the loads developed by metal wires. The load developed by a buckled orthodontic wire is of great concern for molar distalization and cannot be simply derived from mechanical properties measured through classical tests (i.e. tensile, torsion, and bending). A novel testing method, based on the Eulerian approach of a simple supported beam, has been developed in order to measure the load due to buckling of orthodontic wires. Elastic titanium molybdenum alloy (TMA; SDS Ormco) and superelastic Nitinol (3M Unitek) and copper nickel-titanium (NiTi; SDS Ormco) wires, each having a rectangular cross section of 0.016 x 0.022 square inches (0.41 x 0.56 mm(2)), were used. The wires were activated and deactivated by loading and unloading. In order to analyse thermo-mechanical properties in buckling, mechanical tests were assisted by calorimetric measurements through differential scanning calorimetry (DSC). Statistical analysis to determine differences between the samples was undertaken using two-way analysis of variance (ANOVA) and Tukey's post hoc test, and one-way ANOVA to assess differences between the tested wires under similar conditions and different materials. The results suggest that the load due to buckling depends on material composition, wire length, the amount of activation, temperature, and deformation rate. The results can be considered as the lower bound for the loads experienced by teeth as far as a buckled wire is concerned. At a temperature higher than the austenite finish transition temperature, superelastic wires were strongly dependent on temperature and deformation rate. The effect due to an increase of deformation rate was similar to that of a decrease of temperature. Load variations due to temperature of a superelastic wire with a length of 20 mm were estimated to be approximately 4 g/degrees C. The high performance of an applied superelastic wire may be related to the high dynamics of the load in relation to

  13. Wire grid and wire scanner design for the CERN Linac4

    CERN Document Server

    Roncarolo, F; Cheymol, B; Dutriat, C; Duraffourg, M; Focker, G J; Raich, U; Vuitton, C

    2010-01-01

    As part of the CERN LHC injector chain upgrade, LINAC4 [1] will accelerate H- ions from 45 KeV to 160 MeV. A number of wire grids and wire scanners will be used to characterize the beam transverse profile. This paper covers all monitor design aspects intended to cope with the required specifications. In particular, the overall measurement robustness, accuracy and sensitivity must be satisfied for different commissioning and operational scenarios. The physics mechanisms generating the wire signals and the wire resistance to beam induced thermal loads have been considered in order to determine the most appropriate monitor design in terms of wire material and dimensions.

  14. Steer-by-wire innovations and demonstrator

    NARCIS (Netherlands)

    Lupker, H.A.; Zuurbier, J.; Verschuren, R.M.A.F.; Jansen, S.T.H.; Willemsen, D.M.C.

    2002-01-01

    Arguments for 'by-wire' systems include production costs, packaging and traffic safety. Innovations concern both product and development process e.g. combined virtual engineering and Hardware-in-the-loop testing. Three Steer-by-wire systems are discussed: a steering system simulator used as a

  15. Add-On Shielding for Unshielded Wire

    Science.gov (United States)

    Koenig, J. C.; Billitti, J. W.; Tallon, J. M.

    1983-01-01

    Fabrication sequence used to produce compact shields slipped into place from free ends of wires already soldered into connectors at other ends. Single shields are formed into harnesses by connecting grounding jumpers. Technique is especially useful for small diameter wire attached to microminiature connectors.

  16. WIRED magazine announces rave awards nominees

    CERN Multimedia

    2002-01-01

    WIRED Magazine has anounced the nominees for its fourth annual WIRED Rave Awards, celebrating innovation and the individuals transforming commerce and culture. Jeffrey Hangst of the University of Aarhus has been nominated in the science category, for his work on the ATHENA Experiment, CERN (1/2 page).

  17. Kirschner Wire Breakage during Removal Requiring Retrieval

    Directory of Open Access Journals (Sweden)

    Kai Yuen Wong

    2016-01-01

    Full Text Available Kirschner wires (K-wires are widely used for fixation of fractures and dislocations in the hand as they are readily available, reliable, and cost-effective. Complication rates of up to 18% have been reported. However, K-wire breakage during removal is rare. We present one such case illustrating a simple technique for retrieval. A 35-year-old male presented with a distal phalanx fracture of his right middle finger. This open fracture was treated with K-wire fixation. Postoperatively, he developed a pin site infection with associated finger swelling. The K-wire broke during removal with the proximal piece completely retained in his middle phalanx. To minimise risk of osteomyelitis, the K-wire was removed with a novel surgical technique. He had full return of hand function. Intraoperative K-wire breakage has a reported rate of 0.1%. In our case, there was no obvious cause of breakage and the patient denied postoperative trauma. On the other hand, pin site infections are much more common with reported rates of up to 7% in the hand or wrist. K-wire fixation is a simple method for bony stabilisation but can be a demanding procedure with complications often overlooked. It is important to be aware of the potential sequelae.

  18. Emulating Wired Backhaul with Wireless Network Coding

    DEFF Research Database (Denmark)

    Thomsen, Henning; De Carvalho, Elisabeth; Popovski, Petar

    2014-01-01

    , the uplink traffic to the user, remains identical to the one performed in a wired system. In the broadcast phase, the decoding of the downlink traffic can also be guaranteed to remain identical. Hence, our solution claims an emulation of a wired backhaul with wireless network coding with same performance. We...

  19. Wire compensation: Performance, SPS MDs, pulsed system

    CERN Document Server

    Dorda, U

    2008-01-01

    A wire compensation (BBLR) scheme has been proposed in order to improve the long range beam-beam performance of the nominal LHC and its phase 1 and phase 2 upgrades[1]. In this paper we present experimental experience of the CERN SPS wires (BBLR) and report on progress with the RF BBLR.

  20. 75 FR 4584 - Wire Decking From China

    Science.gov (United States)

    2010-01-28

    ... and whether shipped as a kit or packaged separately. Wire decking is produced from carbon or alloy..., zinc or nickel coated), coated (e.g., with paint, epoxy, or plastic), or uncoated (``raw''). The wire... before June 28, 2010, but such final comments must not contain new factual information and must otherwise...

  1. Wire scanners in low energy accelerators

    CERN Document Server

    Elmfors, P; Huhtinen, M; Lindroos, M; Olsfors, J; Raich, U

    1997-01-01

    Fast wire scanners are today considered as part of standard instrumentation in high energy synchrotrons. The extension of their use to synchrotrons working at lower energies, where Coulomb scattering can be important and the transverse beam size is large, introduces new complications considering beam heating of the wire, composition of the secondary particle shower and geometrical consideration in the detection set-up. A major problem in treating these effects is that the creation of secondaries in a thin carbon wire by a energetic primary beam is difficult to describe in an analytical way. We are here presenting new results from a full Monte Carlo simulation of this process yielding information on heat deposited in the wire, particle type and energy spectrum of secondaries and angular dependence as a function of primary beam energy. The results are used to derive limits for the use of wire scanners in low energy accelerators.

  2. Quantum trajectories

    CERN Document Server

    Chattaraj, Pratim Kumar

    2010-01-01

    The application of quantum mechanics to many-particle systems has been an active area of research in recent years as researchers have looked for ways to tackle difficult problems in this area. The quantum trajectory method provides an efficient computational technique for solving both stationary and time-evolving states, encompassing a large area of quantum mechanics. Quantum Trajectories brings the expertise of an international panel of experts who focus on the epistemological significance of quantum mechanics through the quantum theory of motion.Emphasizing a classical interpretation of quan

  3. Quantum electrodynamics

    CERN Document Server

    Bialynicki-Birula, I; Ter Haar, D

    1975-01-01

    Quantum Electrodynamics focuses on the formulation of quantum electrodynamics (QED) in its most general and most abstract form: relativistic quantum field theory. It describes QED as a program, rather than a closed theory, that rests on the theory of the quantum Maxwellian field interacting with given (external) classical sources of radiation and on the relativistic quantum mechanics of electrons interacting with a given (external) classical electromagnetic field.Comprised of eight chapters, this volume begins with an introduction to the fundamental principles of quantum theory formulated in a

  4. Quantum Oscillators

    CERN Document Server

    Blaise, Paul

    2011-01-01

    An invaluable reference for an overall but simple approach to the complexity of quantum mechanics viewed through quantum oscillators Quantum oscillators play a fundamental role in many areas of physics; for instance, in chemical physics with molecular normal modes, in solid state physics with phonons, and in quantum theory of light with photons. Quantum Oscillators is a timely and visionary book which presents these intricate topics, broadly covering the properties of quantum oscillators which are usually dispersed in the literature at varying levels of detail and often combined with other p

  5. Quantum robots and quantum computers

    Energy Technology Data Exchange (ETDEWEB)

    Benioff, P.

    1998-07-01

    Validation of a presumably universal theory, such as quantum mechanics, requires a quantum mechanical description of systems that carry out theoretical calculations and systems that carry out experiments. The description of quantum computers is under active development. No description of systems to carry out experiments has been given. A small step in this direction is taken here by giving a description of quantum robots as mobile systems with on board quantum computers that interact with different environments. Some properties of these systems are discussed. A specific model based on the literature descriptions of quantum Turing machines is presented.

  6. Quantum Darwinism

    Energy Technology Data Exchange (ETDEWEB)

    Zurek, Wojciech H [Los Alamos National Laboratory

    2008-01-01

    Quantum Darwinism - proliferation, in the environment, of multiple records of selected states of the system (its information-theoretic progeny) - explains how quantum fragility of individual state can lead to classical robustness of their multitude.

  7. Quantum cryptography

    OpenAIRE

    Gisin, Nicolas; Ribordy, Grégoire; Tittel, Wolfgang; Zbinden, Hugo

    2002-01-01

    Quantum cryptography could well be the first application of quantum mechanics at the individual quanta level. The very fast progress in both theory and experiments over the recent years are reviewed, with emphasis on open questions and technological issues.

  8. Scaling of geometric quantum discord close to a topological phase transition.

    Science.gov (United States)

    Shan, Chuan-Jia; Cheng, Wei-Wen; Liu, Ji-Bing; Cheng, Yong-Shan; Liu, Tang-Kun

    2014-03-26

    Quantum phase transition is one of the most interesting aspects in quantum many-body systems. Recently, geometric quantum discord has been introduced to signature the critical behavior of various quantum systems. However, it is well-known that topological quantum phase transition can not be described by the conventional Landau's symmetry breaking theory, and thus it is unknown that whether previous study can be applicable in this case. Here, we study the topological quantum phase transition in Kitaev's 1D p-wave spinless quantum wire model in terms of its ground state geometric quantum discord. The derivative of geometric quantum discord is nonanalytic at the critical point, in both zero temperature and finite temperature cases. The scaling behavior and the universality are verified numerically. Therefore, our results clearly show that all the key ingredients of the topological phase transition can be captured by the nearest neighbor and long-range geometric quantum discord.

  9. Quantum Econophysics

    OpenAIRE

    Esteban Guevara Hidalgo

    2006-01-01

    The relationships between game theory and quantum mechanics let us propose certain quantization relationships through which we could describe and understand not only quantum but also classical, evolutionary and the biological systems that were described before through the replicator dynamics. Quantum mechanics could be used to explain more correctly biological and economical processes and even it could encloses theories like games and evolutionary dynamics. This could make quantum mechanics a...

  10. Wire pad chamber for LHCb muon system

    CERN Document Server

    Botchine, B; Lazarev, V A; Sagidova, N; Vorobev, A P; Vorobyov, A; Vorobyov, Alexei

    2000-01-01

    2000-003 Wire pad chambers (WPC) have been proposed for the outer Region 4 of the LHCb Muon System. These are double gap MWPCs with small wire spacing allowing to obtain 99% detection efficiency in a 20 ns time window. The chambers have a rectangular shape with the vertical dimension from 20 cm in Station 1 to 30 cm in Station 5. The horizontal dimensions will be different with the maximal size of 3 meters in Station 5. The wires are in the vertical direction. The short wire length allows to use small wire spacing needed for high time resolution. Also, this helps to obtain the uniform gas gain over the whole chamber area. The WPC has one row of the wire pads formed by grouping wires in separate readout channels. Four WPC prototypes have been built at PNPI and tested in the PS beam at CERN. Here we report on the results from these tests. Also, the results of simulation of the WPC performance are presented.

  11. Quantum cryptography

    NARCIS (Netherlands)

    S. Fehr (Serge)

    2010-01-01

    textabstractQuantum cryptography makes use of the quantum-mechanical behavior of nature for the design and analysis of cryptographic schemes. Optimally (but not always), quantum cryptography allows for the design of cryptographic schemes whose security is guaranteed solely by the laws of nature.

  12. In-Situ Wire Damage Detection System

    Science.gov (United States)

    Williams, Martha; Roberson, Luke; Tate, Lanetra; Smith, Trent; Gibson, Tracy; Medelius, Pedro; Jolley, Scott

    2012-01-01

    An In-Situ Wire Damage Detection System (ISWDDS) has been developed that is capable of detecting damage to a wire insulation, or a wire conductor, or to both. The system will allow for realtime, continuous monitoring of wiring health/integrity and reduce the number of false negatives and false positives while being smaller, lighter in weight, and more robust than current systems. The technology allows for improved safety and significant reduction in maintenance hours for aircraft, space vehicles, satellites, and other critical high-performance wiring systems for industries such as energy production and mining. The integrated ISWDDS is comprised of two main components: (1) a wire with an innermost core conductor, an inner insulation film, a conductive layer or inherently conductive polymer (ICP) covering the inner insulation film, an outermost insulation jacket; and (2) smart connectors and electronics capable of producing and detecting electronic signals, and a central processing unit (CPU) for data collection and analysis. The wire is constructed by applying the inner insulation films to the conductor, followed by the outer insulation jacket. The conductive layer or ICP is on the outer surface of the inner insulation film. One or more wires are connected to the CPU using the smart connectors, and up to 64 wires can be monitored in real-time. The ISWDDS uses time domain reflectometry for damage detection. A fast-risetime pulse is injected into either the core conductor or conductive layer and referenced against the other conductor, producing transmission line behavior. If either conductor is damaged, then the signal is reflected. By knowing the speed of propagation of the pulse, and the time it takes to reflect, one can calculate the distance to and location of the damage.

  13. Experimental setup to detect superconducting wire motion

    Science.gov (United States)

    Ruwali, K.; Yamanaka, A.; Teramoto, Y.; Nakanishi, K.; Hosoyama, K.

    2009-04-01

    An experimental setup was designed and fabricated to study superconducting wire motion under the influence of electromagnetic force. Experiments were conducted at 4.2 K by varying the experimental conditions such as the tension to the superconducting wire and different insulating materials at the interface of the superconducting wire and head part. The insulating materials used in the experiments were polyimide film and a high strength polyethylene fiber cloth, Dyneema. Details of the experimental setup and the test results are reported in this paper.

  14. Experimental setup to detect superconducting wire motion

    Directory of Open Access Journals (Sweden)

    K. Ruwali

    2009-04-01

    Full Text Available An experimental setup was designed and fabricated to study superconducting wire motion under the influence of electromagnetic force. Experiments were conducted at 4.2 K by varying the experimental conditions such as the tension to the superconducting wire and different insulating materials at the interface of the superconducting wire and head part. The insulating materials used in the experiments were polyimide film and a high strength polyethylene fiber cloth, Dyneema. Details of the experimental setup and the test results are reported in this paper.

  15. A fiber-coupled quantum-dot on a photonic tip

    DEFF Research Database (Denmark)

    Cadeddu, Davide; Teissier, Jean; Braakman, Floris R.

    2016-01-01

    We present the experimental realization of a quantum fiber-pigtail. The device consists of a semiconductor quantum-dot embedded into a conical photonic wire that is directly connected to the core of a fiber-pigtail. We demonstrate a photon collection efficiency at the output of the fiber of 5.8% ...

  16. Quantum Piston - Quantum Preservation, Simulation and Transfer In Oxide Nanostructures

    Science.gov (United States)

    2016-06-28

    34 Science 334 (2011) 958-961. 8. Lukasz Fidkowski, Roman M. Lutchyn, Chetan Nayak, Mathew P.A. Fisher, "Majorana Zero Modes in 1D Quantum Wires Without Long... Roman M. Lutchyn, and Chetan Nayak, "Origin and transport signatures of spin-orbit interactions in one- and two-dimensional SrTiO3-based...34, Phys. Rev. B 87, 165421 (2013) 20. Lukasz Fidkowski, Hong-Chen Jiang, Roman M. Lutchyn, and Chetan Nayak, "Magnetic and superconducting ordering in

  17. Quantum Darwinism

    Science.gov (United States)

    Zurek, Wojciech Hubert

    2009-03-01

    Quantum Darwinism describes the proliferation, in the environment, of multiple records of selected states of a quantum system. It explains how the quantum fragility of a state of a single quantum system can lead to the classical robustness of states in their correlated multitude; shows how effective `wave-packet collapse' arises as a result of the proliferation throughout the environment of imprints of the state of the system; and provides a framework for the derivation of Born's rule, which relates the probabilities of detecting states to their amplitudes. Taken together, these three advances mark considerable progress towards settling the quantum measurement problem.

  18. Quantum cheques

    Science.gov (United States)

    Moulick, Subhayan Roy; Panigrahi, Prasanta K.

    2016-06-01

    We propose the idea of a quantum cheque scheme, a cryptographic protocol in which any legitimate client of a trusted bank can issue a cheque, that cannot be counterfeited or altered in anyway, and can be verified by a bank or any of its branches. We formally define a quantum cheque and present the first unconditionally secure quantum cheque scheme and show it to be secure against any no-signalling adversary. The proposed quantum cheque scheme can been perceived as the quantum analog of Electronic Data Interchange, as an alternate for current e-Payment Gateways.

  19. Chemically etched modulation in wire radius for wire array Z-pinch perturbation studies

    Science.gov (United States)

    Jones, B.; Deeney, C.; McKenney, J. L.; Garrity, J. E.; Lobley, D. K.; Martin, K. L.; Griego, A. E.; Ramacciotti, J. P.; Bland, S. N.; Lebedev, S. V.; Bott, S. C.; Ampleford, D. J.; Palmer, J. B. A.; Rapley, J.; Hall, G.

    2004-11-01

    A technique for manufacturing wires with imposed modulation in radius with axial wavelengths as short as 1 mm is presented. Extruded aluminum 5056 with 15 μm diameter was masked and chemically etched to reduce the radius by ˜20% in selected regions. Characterized by scanning electron microscopy, the modulation in radius is a step function with a ˜10 μm wide conical transition between thick and thin segments, with some pitting in etched regions. Techniques for mounting and aligning these wires in arrays for fast z-pinch experiments will be discussed. Axially mass-modulated wire arrays of this type will allow the study of seeded Rayleigh-Taylor instabilities in z pinches, corona formation, wire initiation with varying current density in the wire core, and correlation of perturbations between adjacent wires. This tool will support magnetohydrodynamics code validation in complex three-dimensional geometries, and perhaps x-ray pulse shaping.

  20. Molecular wires, switches and memories

    Science.gov (United States)

    Chen, Jia

    Molecular electronics, an emerging field, makes it possible to build individual molecules capable of performing functions identical or analogous to present- day conductors, switches, or memories. These individual molecules, with a nano-meter scale characteristic length, can be designed and chemically synthesized with specific atoms, geometries and charge distribution. This thesis focuses on the design, and measurements of molecular wires, and related strategically engineered structures-molecular switches and memories. The experimental system relies on a thermodynamically driven self-assembling process to attach molecules onto substrate surfaces without intervention from outside. The following topics will be discussed: directed nanoscale manipulation of self-assembled molecules using scanning tunneling microscope; investigation on through-bond transport of nanoscale symmetric metal/conjugated self- assembled monolayers (SAM)/metal junctions, where non- Ohmic thermionic emission was observed to be the dominant process, with isocyanide-Pd contacts showing the lowest thermionic barrier of 0.22 eV; the first realization of robust and large reversible switching behavior in an electronic device that utilizes molecules containing redox centers as the active component, exhibiting negative differential resistance (NDR) and large on-off peak-to-valley ratio (PVR); observation of erasable storage of higher conductivity states in these redox- center containing molecular devices, and demonstration of a two-terminal electronically programmable and erasable molecular memory cell with long bit retention time.

  1. Milestones Toward Majorana-Based Quantum Computing

    Science.gov (United States)

    Aasen, David; Hell, Michael; Mishmash, Ryan V.; Higginbotham, Andrew; Danon, Jeroen; Leijnse, Martin; Jespersen, Thomas S.; Folk, Joshua A.; Marcus, Charles M.; Flensberg, Karsten; Alicea, Jason

    2016-07-01

    We introduce a scheme for preparation, manipulation, and read out of Majorana zero modes in semiconducting wires with mesoscopic superconducting islands. Our approach synthesizes recent advances in materials growth with tools commonly used in quantum-dot experiments, including gate control of tunnel barriers and Coulomb effects, charge sensing, and charge pumping. We outline a sequence of milestones interpolating between zero-mode detection and quantum computing that includes (1) detection of fusion rules for non-Abelian anyons using either proximal charge sensors or pumped current, (2) validation of a prototype topological qubit, and (3) demonstration of non-Abelian statistics by braiding in a branched geometry. The first two milestones require only a single wire with two islands, and additionally enable sensitive measurements of the system's excitation gap, quasiparticle poisoning rates, residual Majorana zero-mode splittings, and topological-qubit coherence times. These pre-braiding experiments can be adapted to other manipulation and read out schemes as well.

  2. Magnetoimpedance simulations in wires and tubes

    CERN Document Server

    Munoz, J L; Kurlyandskaya, G V; Garcia-Arribas, A

    2002-01-01

    Numerical computations have been used to study the magnetoimpedance (MI) effect in magnetic wires and microtubes. Two kinds of wires have been investigated. In the first case, a typical amorphous wire with a core-shell structure is simulated, considering the different magnetization curve of each layer, and in the second case, a non-magnetic wire with a thin deposited layer of magnetic material is studied. The results of the simulations agree in both cases with the experimental behavior usually found for these samples. They also allow us to explain such features as MI saturation and the influence of the resistivities of the conductive and magnetic layers in microtubes, that can improve MI-based devices.

  3. Beam Profiling through Wire Chambing Tracking

    CERN Document Server

    Nash, W

    2013-01-01

    This note describes the calibration of the Delay Wire Chambers (DWCs) used during test runs of CALICE’s Tungsten Digital Hadron Calorimeter (W-DHCAL) prototype in CERN’s SPS beam line (10 – 300 GeV).

  4. Wire core reactor for nuclear thermal propulsion

    Science.gov (United States)

    Harty, Richard B.; Brengle, Robert G.

    1993-01-01

    Studies have been performed of a compact high-performance nuclear rocket reactor that incorporates a tungsten alloy wire fuel element. This reactor, termed the wire core reactor, can deliver a specific impulse of 1,000 s using an expander cycle and a nozzle expansion ratio of 500 to 1. The core is constructed of layers of 0.8-mm-dia fueled tungsten wires wound over alternate layers of spacer wires, which forms a rugged annular lattice. Hydrogen flow in the core is annular, flowing from inside to outside. In addition to the concepts compact size and good heat transfer, the core has excellent power-flow matching features and can resist vibration and thermal stresses during star-up and shutdown.

  5. Wire Bonder: Kulicke and Soffa Model 4526

    Data.gov (United States)

    Federal Laboratory Consortium — Description:CORAL Name: Wire BonderNeeds Description.Scientific Opportunities / Applications:Wedge bonderSemi-automatic and manual modesIndependent Z-axis control,...

  6. Highly stretchable wrinkled gold thin film wires

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Joshua, E-mail: joshuk7@uci.edu; Park, Sun-Jun; Nguyen, Thao [Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697 (United States); Chu, Michael [Department of Biomedical Engineering, University of California, Irvine, California 92697 (United States); Pegan, Jonathan D. [Department of Materials and Manufacturing Technology, University of California, Irvine, California 92697 (United States); Khine, Michelle, E-mail: mkhine@uci.edu [Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697 (United States); Department of Biomedical Engineering, University of California, Irvine, California 92697 (United States)

    2016-02-08

    With the growing prominence of wearable electronic technology, there is a need to improve the mechanical reliability of electronics for more demanding applications. Conductive wires represent a vital component present in all electronics. Unlike traditional planar and rigid electronics, these new wearable electrical components must conform to curvilinear surfaces, stretch with the body, and remain unobtrusive and low profile. In this paper, the piezoresistive response of shrink induced wrinkled gold thin films under strain demonstrates robust conductive performance in excess of 200% strain. Importantly, the wrinkled metallic thin films displayed negligible change in resistance of up to 100% strain. The wrinkled metallic wires exhibited consistent performance after repetitive strain. Importantly, these wrinkled thin films are inexpensive to fabricate and are compatible with roll to roll manufacturing processes. We propose that these wrinkled metal thin film wires are an attractive alternative to conventional wires for wearable applications.

  7. 30 CFR 77.701-3 - Grounding wires; capacity.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding wires; capacity. 77.701-3 Section 77... MINES Grounding § 77.701-3 Grounding wires; capacity. Where grounding wires are used to ground metallic sheaths, armors, conduits, frames, casings, and other metallic enclosures, such grounding wires will be...

  8. 47 CFR 32.2321 - Customer premises wiring.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Customer premises wiring. 32.2321 Section 32... Customer premises wiring. (a) This account shall include all amounts transferred from the former Account 232, Station Connections, inside wiring subclass. (b) Embedded Customer Premises Wiring is that...

  9. Cobalt chromium sublaminar wires for spinal deformity surgery.

    Science.gov (United States)

    Cluck, Michael W; Skaggs, David L

    2006-09-01

    Biomechanical analysis and retrospective chart review. To determine the mechanical properties of cobalt chromium alloy wires and review the clinical application of the wires as sublaminar implants to correct spinal deformity. Sublaminar wires are commonly used as anchors in spinal deformity surgery. In stainless steel instrumentation systems, single strand wires (Luque wires) may be retightened over time to take advantage of stress relaxation while correcting spinal deformity. Because of the mechanical properties of titanium, solid titanium wires are not used as sublaminar wires. Cobalt chromium alloy is a titanium compatible alloy that can be twisted in a similar fashion to stainless steel sublaminar wires. Comparative tensile tests were performed using cobalt chromium alloy wires and Luque stainless steel wires. In addition, 22 consecutive posterior spinal fusions for idiopathic scoliosis were performed using cobalt chromium alloy wires as sublaminar implants. Yield and ultimate tensile loads for the cobalt chromium alloy wires are on average 66% (P cobalt chromium alloy wires were used as sublaminar implants. Mean preoperative lumbar curve was 52 degrees +/- 14 degrees , which corrected to 17 degrees +/- 8 degrees (68% correction, P cobalt chromium alloy wire over steel wire include greater tensile strength and titanium compatibility. Cobalt chromium alloy solid wires may be used as sublaminar implants with titanium spinal instrumentation with excellent clinical results.

  10. V-groove gratings on silicon for infrared beam splitting: comment.

    Science.gov (United States)

    Turunen, J; Noponen, E

    1996-02-10

    In a recent paper [Appl. Opt. 34, 2556 (1995)] beam-splitter gratings with one or more v-shaped features within the period were designed by the complex-amplitude transmittance method. We argue that this approach leads to incorrect results in the geometries considered and provide the evidence of its failure by numerical calculations based on rigorous electromagnetic diffraction theory.

  11. High density, optically corrected, micro-channel cooled, v-groove monolithic laser diode array

    Science.gov (United States)

    Freitas, Barry L.

    1998-01-01

    An optically corrected, micro-channel cooled, high density laser diode array achieves stacking pitches to 33 bars/cm by mounting laser diodes into V-shaped grooves. This design will deliver>4kW/cm2 of directional pulsed laser power. This optically corrected, micro-channel cooled, high density laser is usable in all solid state laser systems which require efficient, directional, narrow bandwidth, high optical power density pump sources.

  12. Audio wiring guide how to wire the most popular audio and video connectors

    CERN Document Server

    Hechtman, John

    2012-01-01

    Whether you're a pro or an amateur, a musician or into multimedia, you can't afford to guess about audio wiring. The Audio Wiring Guide is a comprehensive, easy-to-use guide that explains exactly what you need to know. No matter the size of your wiring project or installation, this handy tool provides you with the essential information you need and the techniques to use it. Using The Audio Wiring Guide is like having an expert at your side. By following the clear, step-by-step directions, you can do professional-level work at a fraction of the cost.

  13. A Magnetic Sensor with Amorphous Wire

    Directory of Open Access Journals (Sweden)

    Dongfeng He

    2014-06-01

    Full Text Available Using a FeCoSiB amorphous wire and a coil wrapped around it, we have developed a sensitive magnetic sensor. When a 5 mm long amorphous wire with the diameter of 0.1 mm was used, the magnetic field noise spectrum of the sensor was about 30 pT/ÖHz above 30 Hz. To show the sensitivity and the spatial resolution, the magnetic field of a thousand Japanese yen was scanned with the magnetic sensor.

  14. Graphene wire medium: Homogenization and application

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Chigrin, Dmitry N.; Lavrinenko, Andrei

    2012-01-01

    In this contribution we analyze numerically the optical properties of the graphene wire medium, which unit cell consists of a stripe of graphene embedded into dielectric. We propose a simple method for retrieval of the isofrequency contour and effective permittivity tensor. As an example...... of the graphene wire medium application we demonstrate a reconfigurable hyperlens for the terahertz subwavelength imaging capable of resolving two sources with separation λ0/5 in the far-field....

  15. Subwavelength wire array metamaterial microwave cavities

    Science.gov (United States)

    Al-Rubaiee, M.; Alchalaby, A.; Al-Janabi, H.

    2018-01-01

    Wire array metamaterial cavities and waveguides can be achieved by changing the resonance frequency of one or more unit cell surrounding by unit cells don't support the resonance for certain frequency and hence obtain signal confinement only on the defect wires. Changing the resonance frequency of one or more unit cell was done in this work by changing the length of the unit cell. We validate our approach in experiment and simulation with electromagnetic waves in the microwave range.

  16. Novel use of the "buddy"wire.

    LENUS (Irish Health Repository)

    O'Hare, A

    2008-12-29

    Summary: During interventional procedures the tortuosity of the vasculature hampers catheter stability. The buddy wire may be used to aid and maintain vascular access.We describe a case of acute subarachnoid haemorrhage secondary to dissecting aneurysm of the vertebral artery.We discuss the value of the buddy wire during balloon occlusion of the vertebral artery not as it is typically used, but to actually prevent the balloon repeatedly entering the posterior inferior cerebellar artery during the procedure.

  17. Wiring System Diagnostic Techniques for Legacy Aircraft

    Science.gov (United States)

    2003-02-01

    Reunions des specialistes des techniques de estion du cycle de vie pour vehicules aeriens vieillissants ] To order the complete compilation report, use...Ageing Mechanisms and Control. Specialists’ Meeting on Life Management Techniques for Ageing Air Vehicles [Les mecanismes vieillissants et le controle...be identified. Additionally, wiring failures tend to be intermittent in nature and can take considerable time to isolate. Wire modifications and

  18. Quantum conductance staircase of holes in silicon nanosandwiches

    Directory of Open Access Journals (Sweden)

    Nikolay T. Bagraev

    2017-03-01

    Full Text Available The results of studying the quantum conductance staircase of holes in one-dimensional channels obtained by the split-gate method inside silicon nanosandwiches that are the ultra-narrow quantum well confined by the delta barriers heavily doped with boron on the n-type Si (100 surface are reported. Since the silicon quantum wells studied are ultra-narrow (~2 nm and confined by the delta barriers that consist of the negative-U dipole boron centers, the quantized conductance of one-dimensional channels is observed at relatively high temperatures (T>77 K. Further, the current-voltage characteristic of the quantum conductance staircase is studied in relation to the kinetic energy of holes and their sheet density in the quantum wells. The results show that the quantum conductance staircase of holes in p-Si quantum wires is caused by independent contributions of the one-dimensional (1D subbands of the heavy and light holes. In addition, the field-related inhibition of the quantum conductance staircase is demonstrated in the situation when the energy of the field-induced heating of the carriers become comparable to the energy gap between the 1D subbands. The use of the split-gate method made it possible to detect the effect of a drastic increase in the height of the quantum conductance steps when the kinetic energy of holes is increased; this effect is most profound for quantum wires of finite length, which are not described under conditions of a quantum point contact. In the concluding section of this paper we present the findings for the quantum conductance staircase of holes that is caused by the edge channels in the silicon nanosandwiches prepared within frameworks of the Hall geometry. This longitudinal quantum conductance staircase, Gxx, is revealed by the voltage applied to the Hall contacts, with the plateaus and steps that bring into correlation respectively with the odd and even fractional values.

  19. Subchannel Analysis of Wire Wrapped SCWR Assembly

    Directory of Open Access Journals (Sweden)

    Jianqiang Shan

    2014-01-01

    Full Text Available Application of wire wrap spacers in SCWR can reduce pressure drop and obtain better mixing capability. As a consequence, the required coolant pumping power is decreased and the coolant temperature profile inside the fuel bundle is flattened which will obviously decrease the peak cladding temperature. The distributed resistance model for wire wrap was developed and implemented in ATHAS subchannel analysis code. The HPLWR wire wrapped assembly was analyzed. The results show that: (1 the assembly with wire wrap can obtain a more uniform coolant temperature profile than the grid spaced assembly, which will result in a lower peak cladding temperature; (2 the pressure drop in a wire wrapped assembly is less than that in a grid spaced assembly, which can reduce the operating power of pump effectively; (3 the wire wrap pitch has significant effect on the flow in the assembly. Smaller Hwire/Drod will result in stronger cross flow a more uniform coolant temperature profile, and also a higher pressure drop.

  20. Induced Voltage in an Open Wire

    Science.gov (United States)

    Morawetz, K.; Gilbert, M.; Trupp, A.

    2017-07-01

    A puzzle arising from Faraday's law has been considered and solved concerning the question which voltage will be induced in an open wire with a time-varying homogeneous magnetic field. In contrast to closed wires where the voltage is determined by the time variance of the magnetic field and the enclosed area, in an open wire we have to integrate the electric field along the wire. It is found that the longitudinal electric field with respect to the wave vector contributes with 1/3 and the transverse field with 2/3 to the induced voltage. In order to find the electric fields the sources of the magnetic fields are necessary to know. The representation of a spatially homogeneous and time-varying magnetic field implies unavoidably a certain symmetry point or symmetry line which depend on the geometry of the source. As a consequence the induced voltage of an open wire is found to be the area covered with respect to this symmetry line or point perpendicular to the magnetic field. This in turn allows to find the symmetry points of a magnetic field source by measuring the voltage of an open wire placed with different angles in the magnetic field. We present exactly solvable models of the Maxwell equations for a symmetry point and for a symmetry line, respectively. The results are applicable to open circuit problems like corrosion and for astrophysical applications.

  1. The technology of testing the safety of steel wire ropes

    Science.gov (United States)

    Zhang, Xiaochun; Hu, Caiwen

    2005-12-01

    To estimate the security of steel wire rope, the broken wire condition, the capability of the rope to bear weight and the state of stress balance of each wire in the steel wire rope were investigated. The wavelet translation method was applied to analyze the signals of magnetic field leakage from the steel wire rope. The result of the time-frequency analysis of the signals can be used to make certain of he position and the amount of the broken wire. Using the static surveillance method as a basis, a dynamic surveillance method was designed to detect the stress balance of the steel wire rope. This technology makes it possible to check the stress condition of each wire on line. It can be concluded that a wavelet translation analysis and the dynamic surveillance technique are effective methods to detect on line and real-time the broken wire and the stress balance of multistrand wire ropes.

  2. Quantum coherence versus quantum uncertainty

    Science.gov (United States)

    Luo, Shunlong; Sun, Yuan

    2017-08-01

    The notion of measurement is of both foundational and instrumental significance in quantum mechanics, and coherence destroyed by measurements (decoherence) lies at the very heart of quantum to classical transition. Qualitative aspects of this spirit have been widely recognized and analyzed ever since the inception of quantum theory. However, axiomatic and quantitative investigations of coherence are attracting great interest only recently with several figures of merit for coherence introduced [Baumgratz, Cramer, and Plenio, Phys. Rev. Lett. 113, 140401 (2014), 10.1103/PhysRevLett.113.140401]. While these resource theoretic approaches have many appealing and intuitive features, they rely crucially on various notions of incoherent operations which are sophisticated, subtle, and not uniquely defined, as have been critically assessed [Chitambar and Gour, Phys. Rev. Lett. 117, 030401 (2016), 10.1103/PhysRevLett.117.030401]. In this paper, we elaborate on the idea that coherence and quantum uncertainty are dual viewpoints of the same quantum substrate, and address coherence quantification by identifying coherence of a state (with respect to a measurement) with quantum uncertainty of a measurement (with respect to a state). Consequently, coherence measures may be set into correspondence with measures of quantum uncertainty. In particular, we take average quantum Fisher information as a measure of quantum uncertainty, and introduce the corresponding measure of coherence, which is demonstrated to exhibit desirable properties. Implications for interpreting quantum purity as maximal coherence, and quantum discord as minimal coherence, are illustrated.

  3. 75 FR 60480 - In the Matter of Certain Bulk Welding Wire Containers and Components Thereof and Welding Wire...

    Science.gov (United States)

    2010-09-30

    ... COMMISSION In the Matter of Certain Bulk Welding Wire Containers and Components Thereof and Welding Wire... importation, or the sale within the United States after importation of certain bulk welding wire containers, components thereof, and welding wire by reason of infringement of certain claims of United States Patent Nos...

  4. Use of a tip-edge stage-1 wire to enhance vertical control during straight wire treatment: two case reports.

    Science.gov (United States)

    Taylor, Helen

    2003-02-01

    Vertical control is one of the problems occasionally encountered in Straight wire treatment. Two cases, one with deep overbite and one with anterior open-bite, demonstrate the use of a Tip-Edge stage-1 wire to enhance vertical control in conjunction with Straight wire brackets and superelastic main arch wires.

  5. Quantum games as quantum types

    Science.gov (United States)

    Delbecque, Yannick

    In this thesis, we present a new model for higher-order quantum programming languages. The proposed model is an adaptation of the probabilistic game semantics developed by Danos and Harmer [DH02]: we expand it with quantum strategies which enable one to represent quantum states and quantum operations. Some of the basic properties of these strategies are established and then used to construct denotational semantics for three quantum programming languages. The first of these languages is a formalisation of the measurement calculus proposed by Danos et al. [DKP07]. The other two are new: they are higher-order quantum programming languages. Previous attempts to define a denotational semantics for higher-order quantum programming languages have failed. We identify some of the key reasons for this and base the design of our higher-order languages on these observations. The game semantics proposed in this thesis is the first denotational semantics for a lambda-calculus equipped with quantum types and with extra operations which allow one to program quantum algorithms. The results presented validate the two different approaches used in the design of these two new higher-order languages: a first one where quantum states are used through references and a second one where they are introduced as constants in the language. The quantum strategies presented in this thesis allow one to understand the constraints that must be imposed on quantum type systems with higher-order types. The most significant constraint is the fact that abstraction over part of the tensor product of many unknown quantum states must not be allowed. Quantum strategies are a new mathematical model which describes the interaction between classical and quantum data using system-environment dialogues. The interactions between the different parts of a quantum system are described using the rich structure generated by composition of strategies. This approach has enough generality to be put in relation with other

  6. On-Chip Single-Plasmon Nanocircuit Driven by a Self-Assembled Quantum Dot.

    Science.gov (United States)

    Wu, Xiaofei; Jiang, Ping; Razinskas, Gary; Huo, Yongheng; Zhang, Hongyi; Kamp, Martin; Rastelli, Armando; Schmidt, Oliver G; Hecht, Bert; Lindfors, Klas; Lippitz, Markus

    2017-07-12

    Quantum photonics holds great promise for future technologies such as secure communication, quantum computation, quantum simulation, and quantum metrology. An outstanding challenge for quantum photonics is to develop scalable miniature circuits that integrate single-photon sources, linear optical components, and detectors on a chip. Plasmonic nanocircuits will play essential roles in such developments. However, for quantum plasmonic circuits, integration of stable, bright, and narrow-band single photon sources in the structure has so far not been reported. Here we present a plasmonic nanocircuit driven by a self-assembled GaAs quantum dot. Through a planar dielectric-plasmonic hybrid waveguide, the quantum dot efficiently excites narrow-band single plasmons that are guided in a two-wire transmission line until they are converted into single photons by an optical antenna. Our work demonstrates the feasibility of fully on-chip plasmonic nanocircuits for quantum optical applications.

  7. Random-matrix theory of quantum transport

    Energy Technology Data Exchange (ETDEWEB)

    Beenakker, C.W. [Instituut-Lorentz, University of Leiden, 2300 RA Leiden, (The Netherlands)

    1997-07-01

    This is a review of the statistical properties of the scattering matrix of a mesoscopic system. Two geometries are contrasted: A quantum dot and a disordered wire. The quantum dot is a confined region with a chaotic classical dynamics, which is coupled to two electron reservoirs via point contacts. The disordered wire also connects two reservoirs, either directly or via a point contact or tunnel barrier. One of the two reservoirs may be in the superconducting state, in which case conduction involves Andreev reflection at the interface with the superconductor. In the case of the quantum dot, the distribution of the scattering matrix is given by either Dyson{close_quote}s circular ensemble for ballistic point contacts or the Poisson kernel for point contacts containing a tunnel barrier. In the case of the disordered wire, the distribution of the scattering matrix is obtained from the Dorokhov-Mello-Pereyra-Kumar equation, which is a one-dimensional scaling equation. The equivalence is discussed with the nonlinear {sigma} model, which is a supersymmetric field theory of localization. The distribution of scattering matrices is applied to a variety of physical phenomena, including universal conductance fluctuations, weak localization, Coulomb blockade, sub-Poissonian shot noise, reflectionless tunneling into a superconductor, and giant conductance oscillations in a Josephson junction. {copyright} {ital 1997} {ital The American Physical Society}

  8. The Analysis of the High Speed Wire Drawing Process of High Carbon Steel Wires Under Hydrodynamic Lubrication Conditions

    Directory of Open Access Journals (Sweden)

    Suliga M.

    2015-04-01

    Full Text Available In this work the analysis of the wire drawing process in hydrodynamic dies has been done. The drawing process of φ5.5 mm wire rod to the final wire of φ1.7 mm was conducted in 12 passes, in drawing speed range of 5-25 m/s. For final wires of φ1.7 mm the investigation of topography of wire surface, the amount of lubricant on the wire surface and the pressure of lubricant in hydrodynamic dies were determined. Additionally, in the work selected mechanical properties of the wires have been estimated.

  9. Resonant-state expansion of the Green's function of open quantum systems

    OpenAIRE

    Hatano, Naomichi; Ordonez, Gonzalo

    2010-01-01

    Our series of recent work on the transmission coefficient of open quantum systems in one dimension will be reviewed. The transmission coefficient is equivalent to the conductance of a quantum dot connected to leads of quantum wires. We will show that the transmission coefficient is given by a sum over all discrete eigenstates without a background integral. An apparent "background" is in fact not a background but generated by tails of various resonance peaks. By using the expression, we will s...

  10. Synthesis of porous silicon nano-wires and the emission of red luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Congli, Sun [School of Materials Science and Engineering, Sichuan University (China); Hao, Hu [National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, Sichuan (China); Huanhuan, Feng; Jingjing, Xu; Yu, Chen; Yong, Jin; Zhifeng, Jiao [School of Materials Science and Engineering, Sichuan University (China); Xiaosong, Sun, E-mail: sunxs@scu.edu.cn [School of Materials Science and Engineering, Sichuan University (China)

    2013-10-01

    This very paper is focusing on the characterization of porous silicon nano-wires prepared via a two-step route, the electroless chemical etching and the following post-treatment of HF/HNO{sub 3} solution. Hence, scanning electron microscopy, transmission electron microscopy and confocal fluorescence microscopy are employed for this purpose. From the results of experiments, one can find that the as-prepared silicon nano-wire is of smooth surface and that no visible photo-luminescence emission could be seen. However, the porous structure can be found in the silicon nano-wire treated with HF/HNO{sub 3} solution, and the clear photo-luminescence emission of 630 nm can be recorded with a confocal fluorescence microscope. The transmission electron microscopy test tells that the porous silicon nano-wire is made up of a porous crystalline silicon nano-core and a rough coating of silicon oxide. Besides, based on the post-HF- and -H{sub 2}O{sub 2}- treatments, the emission mechanism of the red luminescence has been discussed and could be attributed to the quantum confinement/luminescence center model which could be simply concluded as that the electron–hole pairs are mainly excited inside the porous silicon nano-core and then tunneling out and recombining at the silicon oxide coating.

  11. Cross-conjugation and quantum interference : a general correlation?

    NARCIS (Netherlands)

    Valkenier, Hennie; Guedon, Constant M.; Markussen, Troels; Thygesen, Kristian S.; van der Molen, Sense J.; Hummelen, Jan C.

    2014-01-01

    We discuss the relationship between the pi-conjugation pattern, molecular length, and charge transport properties of molecular wires, both from an experimental and a theoretical viewpoint. Specifically, we focus on the role of quantum interference in the conductance properties of cross-conjugated

  12. Novel interference effects and a new quantum phase in mesoscopic ...

    Indian Academy of Sciences (India)

    and Б¾ are positive and flow in the same direction of applied fields. But for quantum wires, a simple scattering solution of the Schrцdinger equation shows that the above conditions break down. At certain Fermi energies and values of loop parameter one can realize such situations as Б½. Б which automatically requires Б¾.

  13. Novel quantum phases, excitations, and transport in low dimensional systems

    NARCIS (Netherlands)

    Makogon, D.|info:eu-repo/dai/nl/304832065

    2010-01-01

    The Chapter 2 is devoted to the study of the transport properties of a quantum wire, described by the Tomonaga-Luttinger model, in the presence of a backscattering potential provided by several point-like or extended time-dependent impurities (barriers) and find regimes of conductance enhancement.

  14. Quantum flywheel

    Science.gov (United States)

    Levy, Amikam; Diósi, Lajos; Kosloff, Ronnie

    2016-05-01

    In this work we present the concept of a quantum flywheel coupled to a quantum heat engine. The flywheel stores useful work in its energy levels, while additional power is extracted continuously from the device. Generally, the energy exchange between a quantum engine and a quantized work repository is accompanied by heat, which degrades the charging efficiency. Specifically when the quantum harmonic oscillator acts as a work repository, quantum and thermal fluctuations dominate the dynamics. Quantum monitoring and feedback control are applied to the flywheel in order to reach steady state and regulate its operation. To maximize the charging efficiency one needs a balance between the information gained by measuring the system and the information fed back to the system. The dynamics of the flywheel are described by a stochastic master equation that accounts for the engine, the external driving, the measurement, and the feedback operations.

  15. Quantifying Quantumness

    Science.gov (United States)

    Braun, Daniel; Giraud, Olivier; Braun, Peter A.

    2010-03-01

    We introduce and study a measure of ``quantumness'' of a quantum state based on its Hilbert-Schmidt distance from the set of classical states. ``Classical states'' were defined earlier as states for which a positive P-function exists, i.e. they are mixtures of coherent states [1]. We study invariance properties of the measure, upper bounds, and its relation to entanglement measures. We evaluate the quantumness of a number of physically interesting states and show that for any physical system in thermal equilibrium there is a finite critical temperature above which quantumness vanishes. We then use the measure for identifying the ``most quantum'' states. Such states are expected to be potentially most useful for quantum information theoretical applications. We find these states explicitly for low-dimensional spin-systems, and show that they possess beautiful, highly symmetric Majorana representations. [4pt] [1] Classicality of spin states, Olivier Giraud, Petr Braun, and Daniel Braun, Phys. Rev. A 78, 042112 (2008)

  16. Quantum Hydrodynamics

    CERN Document Server

    Khan, Shabbir A

    2013-01-01

    Quantum plasma physics is a rapidly evolving research field with a very inter-disciplinary scope of potential applications, ranging from nano-scale science in condensed matter to the vast scales of astrophysical objects. The theoretical description of quantum plasmas relies on various approaches, microscopic or macroscopic, some of which have obvious relation to classical plasma models. The appropriate model should, in principle, incorporate the quantum mechanical effects such as diffraction, spin statistics and correlations, operative on the relevant scales. However, first-principle approaches such as quantum Monte Carlo and density functional theory or quantum-statistical methods such as quantum kinetic theory or non-equilibrium Green's functions require substantial theoretical and computational efforts. Therefore, for selected problems, alternative simpler methods have been put forward. In particular, the collective behavior of many-body systems is usually described within a self-consistent scheme of parti...

  17. Quantum cryptography

    CERN Document Server

    Gilbert, Gerald; Hamrick, Michael

    2013-01-01

    This book provides a detailed account of the theory and practice of quantum cryptography. Suitable as the basis for a course in the subject at the graduate level, it crosses the disciplines of physics, mathematics, computer science and engineering. The theoretical and experimental aspects of the subject are derived from first principles, and attention is devoted to the practical development of realistic quantum communications systems. The book also includes a comprehensive analysis of practical quantum cryptography systems implemented in actual physical environments via either free-space or fiber-optic cable quantum channels. This book will be a valuable resource for graduate students, as well as professional scientists and engineers, who desire an introduction to the field that will enable them to undertake research in quantum cryptography. It will also be a useful reference for researchers who are already active in the field, and for academic faculty members who are teaching courses in quantum information s...

  18. Quantum measurement

    CERN Document Server

    Busch, Paul; Pellonpää, Juha-Pekka; Ylinen, Kari

    2016-01-01

    This is a book about the Hilbert space formulation of quantum mechanics and its measurement theory. It contains a synopsis of what became of the Mathematical Foundations of Quantum Mechanics since von Neumann’s classic treatise with this title. Fundamental non-classical features of quantum mechanics—indeterminacy and incompatibility of observables, unavoidable measurement disturbance, entanglement, nonlocality—are explicated and analysed using the tools of operational quantum theory. The book is divided into four parts: 1. Mathematics provides a systematic exposition of the Hilbert space and operator theoretic tools and relevant measure and integration theory leading to the Naimark and Stinespring dilation theorems; 2. Elements develops the basic concepts of quantum mechanics and measurement theory with a focus on the notion of approximate joint measurability; 3. Realisations offers in-depth studies of the fundamental observables of quantum mechanics and some of their measurement implementations; and 4....

  19. Harnessing Light with Photonic Nanowires: Fundamentals and Applications to Quantum Optics (ChemPhysChem 11/2013)

    DEFF Research Database (Denmark)

    Claudon, Julien; Gregersen, Niels; Lalanne, Philippe

    2013-01-01

    Artist view of an optical antenna based on a tailored photonic wire, as it is discussed by J. Claudon et al. on p. 2393. The antenna exploits both the broadband spontaneous emission control offered by a single-mode photonic wire and the engineering of its far-field emission, using a planar mirror...... and a top conical taper. By inserting a quantum dot inside the wire, one realizes a very bright single-photon source. Beyond this first application, such a structure opens appealing perspectives for the future developments of solid-state quantum optics....

  20. Quantum Locality

    OpenAIRE

    Stapp, Henry

    2009-01-01

    Robert Griffiths has recently addressed, within the framework of a 'consistent quantum theory' that he has developed, the issue of whether, as is often claimed, quantum mechanics entails a need for faster-than-light transfers of information over long distances. He argues that the putative proofs of this property that involve hidden variables include in their premises some essentially classical-physics-type assumptions that are fundamentally incompatible with the precepts of quantum physics. O...

  1. Quantum ratchets

    OpenAIRE

    Peguiron, J.

    1997-01-01

    In this thesis, ratchet systems operating in the quantum regime are investigated. Ratchet systems, also known as Brownian motors, are periodic systems presenting an intrinsic asymmetry which can be exploited to extract work out of unbiased forces. As a model for ratchet systems, we consider the motion of a particle in a one-dimensional periodic and asymmetric potential, interacting with a thermal environment, and subject to an unbiased driving force. In quantum ratchets, intrinsic quantum flu...

  2. STRS SpaceWire FPGA Module

    Science.gov (United States)

    Lux, James P.; Taylor, Gregory H.; Lang, Minh; Stern, Ryan A.

    2011-01-01

    An FPGA module leverages the previous work from Goddard Space Flight Center (GSFC) relating to NASA s Space Telecommunications Radio System (STRS) project. The STRS SpaceWire FPGA Module is written in the Verilog Register Transfer Level (RTL) language, and it encapsulates an unmodified GSFC core (which is written in VHDL). The module has the necessary inputs/outputs (I/Os) and parameters to integrate seamlessly with the SPARC I/O FPGA Interface module (also developed for the STRS operating environment, OE). Software running on the SPARC processor can access the configuration and status registers within the SpaceWire module. This allows software to control and monitor the SpaceWire functions, but it is also used to give software direct access to what is transmitted and received through the link. SpaceWire data characters can be sent/received through the software interface, as well as through the dedicated interface on the GSFC core. Similarly, SpaceWire time codes can be sent/received through the software interface or through a dedicated interface on the core. This innovation is designed for plug-and-play integration in the STRS OE. The SpaceWire module simplifies the interfaces to the GSFC core, and synchronizes all I/O to a single clock. An interrupt output (with optional masking) identifies time-sensitive events within the module. Test modes were added to allow internal loopback of the SpaceWire link and internal loopback of the client-side data interface.

  3. Forecasting of Corrosion Properties of Steel Wires for Production of Guide Wires for Cardiological Treatment

    National Research Council Canada - National Science Library

    Przondziono, J; Walke, W; Hadasik, E; Młynarski, R

    2013-01-01

    ... of guide wires used in invasive cardiology. The results of static tensile test enabled us to determine the course of flow curve of wires made of X10CrNi 18-8 steel as well as mathematical form of flow stress function...

  4. Modeling and simulation of the fluid flow in wire electrochemical machining with rotating tool (wire ECM)

    Science.gov (United States)

    Klocke, F.; Herrig, T.; Zeis, M.; Klink, A.

    2017-10-01

    Combining the working principle of electrochemical machining (ECM) with a universal rotating tool, like a wire, could manage lots of challenges of the classical ECM sinking process. Such a wire-ECM process could be able to machine flexible and efficient 2.5-dimensional geometries like fir tree slots in turbine discs. Nowadays, established manufacturing technologies for slotting turbine discs are broaching and wire electrical discharge machining (wire EDM). Nevertheless, high requirements on surface integrity of turbine parts need cost intensive process development and - in case of wire-EDM - trim cuts to reduce the heat affected rim zone. Due to the process specific advantages, ECM is an attractive alternative manufacturing technology and is getting more and more relevant for sinking applications within the last few years. But ECM is also opposed with high costs for process development and complex electrolyte flow devices. In the past, few studies dealt with the development of a wire ECM process to meet these challenges. However, previous concepts of wire ECM were only suitable for micro machining applications. Due to insufficient flushing concepts the application of the process for machining macro geometries failed. Therefore, this paper presents the modeling and simulation of a new flushing approach for process assessment. The suitability of a rotating structured wire electrode in combination with an axial flushing for electrodes with high aspect ratios is investigated and discussed.

  5. Quantum information and computation

    OpenAIRE

    Bub, Jeffrey

    2005-01-01

    This article deals with theoretical developments in the subject of quantum information and quantum computation, and includes an overview of classical information and some relevant quantum mechanics. The discussion covers topics in quantum communication, quantum cryptography, and quantum computation, and concludes by considering whether a perspective in terms of quantum information sheds new light on the conceptual problems of quantum mechanics.

  6. Quantum information

    CERN Document Server

    Barnett, Stephen M

    2009-01-01

    Quantum information- the subject- is a new and exciting area of science, which brings together physics, information theory, computer science and mathematics. "Quantum Information"- the book- is based on two successful lecture courses given to advanced undergraduate and beginning postgraduate students in physics. The intention is to introduce readers at this level to the fundamental, but offer rather simple, ideas behind ground-breaking developments including quantum cryptography,teleportation and quantum computing. The text is necessarily rather mathematical in style, but the mathema

  7. Quantum Optics

    CERN Document Server

    Vogel, Werner

    2006-01-01

    This is the third, revised and extended edition of the acknowledged "Lectures on Quantum Optics" by W. Vogel and D.-G. Welsch.It offers theoretical concepts of quantum optics, with special emphasis on current research trends. A unified concept of measurement-based nonclassicality and entanglement criteria and a unified approach to medium-assisted electromagnetic vacuum effects including Van der Waals and Casimir Forces are the main new topics that are included in the revised edition. The rigorous development of quantum optics in the context of quantum field theory and the attention to details makes the book valuable to graduate students as well as to researchers

  8. Single and double valence configuration interactions for recovering the exponential decay law while tunneling through a molecular wire

    Science.gov (United States)

    Portais, Mathilde; Hliwa, Mohamed; Joachim, Christian

    2016-01-01

    The exponential decay of the electronic transmission through a molecular wire with its length is calculated using a configuration interaction elastic scattering quantum chemistry (CI-ESQC) theory [1, 2]. In the HOMO-LUMO gap and in a one-electron approximation, this decay is exponential since the scattering matrix comes from a product of spatial propagators along the wire. In a valence SD-CI (single and double-configurations interaction) description, such a product does not exist. An effective one was numerically obtained from the CI-ESQC scattering matrix. Fluctuations over the effective CI-exponential decay come from the truncation of the full CI basis set and also from many-body exchange-correlation effects along the molecular wire.

  9. Magnetization and Inter-Filament Contact in HEP and ITER Bronze-Route Nb(3)Sn Wires

    CERN Document Server

    Bordini, B; Devred, A; Richter, D; Bessette, D; Jewell, M; Bottura, L

    2011-01-01

    Magnetization measurements are relevant tests for the characterization of superconductors. Practically they are the only measurements that allow estimating the critical current density at low fields of low temperature superconductors, the effective filament size and the hysteresis losses. For this purpose CERN, in collaboration with the University of Geneva, has carried out magnetization measurements on five types of Nb(3)Sn wires: three bronze route strands used in the ITER project; one Powder In Tube (PIT) and one Internal Tin (IT) wires used for developing next generation accelerator magnets. The field dependent magnetization has been determined using three setups: a Vibrating Sample Magnetometer (VSM), a Superconducting Quantum Interference Device (SQUID) and a special system used for the production control of LHC strands. Samples of different lengths have been tested to check the different coupling between the filaments. Unexpectedly, it was found that the magnetization of the tested bronze wires was str...

  10. Magnetization and Inter-Filament Contact in HEP and ITER Bronze-Route Nb3Sn Wires

    CERN Document Server

    Bordini, B; Bottura, L; Devred, A; Jewell, M; Richter, D; Senatore, C

    2011-01-01

    Magnetization measurements are relevant tests for the characterization of superconductors. Practically they are the only measurements that allow estimating the critical current density at low fields of low temperature superconductors, the effective filament size and the hysteresis losses. For this purpose CERN, in collaboration with the University of Geneva, has carried out magnetization measurements on five types of Nb3Sn wires: three bronze route strands used in the ITER project; one Powder In Tube (PIT) and one Internal Tin (IT) wires used for developing next generation accelerator magnets. The field dependent magnetization has been determined using three set-ups: a Vibrating Sample Magnetometer (VSM), a Superconducting Quantum Interference Device (SQUID) and a special system used for the production control of LHC strands. Samples of different lengths have been tested to check the different coupling between the filaments. Unexpectedly, it was found that the magnetization of the tested bronze wires was stro...

  11. The impact of microcavity wire width on polariton soliton existence and multistability

    Science.gov (United States)

    Slavcheva, G.; Koleva, M. V.; Pimenov, A.

    2017-06-01

    We have developed a model of the nonlinear polariton dynamics in realistic 3D non-planar microcavity wires in the driven-dissipative regime. We find that the typical microcavity optical bistability evolves into multistability upon variation of the model parameters. The origin of the multistability is discussed in detail. We apply linear perturbation analysis to modulational instabilities, and identify conditions for localisation of composite multi-mode polariton solitons in the triggered parametric oscillator regime. Further, we demonstrate stable polariton soliton propagation in tilted and tapered waveguides, and determine maximum tilt angles for which solitons still exist. Additionally, we study soliton amplitude and velocity dependence on the wire width, with a view to engineering quantum photonic devices.

  12. Quantum physics without quantum philosophy

    Energy Technology Data Exchange (ETDEWEB)

    Duerr, Detlef [Muenchen Univ. (Germany). Mathematisches Inst.; Goldstein, Sheldon [Rutgers State Univ., Piscataway, NJ (United States). Dept. of Mathematics; Zanghi, Nino [Genova Univ. (Italy); Istituto Nazionale Fisica Nucleare, Genova (Italy)

    2013-02-01

    Integrates and comments on the authors' seminal papers in the field. Emphasizes the natural way in which quantum phenomena emerge from the Bohmian picture. Helps to answer many of the objections raised to Bohmian quantum mechanics. Useful overview and summary for newcomers and students. It has often been claimed that without drastic conceptual innovations a genuine explanation of quantum interference effects and quantum randomness is impossible. This book concerns Bohmian mechanics, a simple particle theory that is a counterexample to such claims. The gentle introduction and other contributions collected here show how the phenomena of non-relativistic quantum mechanics, from Heisenberg's uncertainty principle to non-commuting observables, emerge from the Bohmian motion of particles, the natural particle motion associated with Schroedinger's equation. This book will be of value to all students and researchers in physics with an interest in the meaning of quantum theory as well as to philosophers of science.

  13. K-wire position in tension-band wiring technique affects stability of wires and long-term outcome in surgical treatment of olecranon fractures.

    NARCIS (Netherlands)

    Linden, S.C. van der; Kampen, A. van; Jaarsma, R.L.

    2012-01-01

    BACKGROUND: Tension-band wiring (TBW) has been accepted as the treatment of choice for displaced olecranon fractures. The aim of this study was to examine the effect of K-wire position on instability of the K-wires in relation to local complications and radiological and clinical long-term outcome.

  14. Modeling and experimentation of a positioning system of SMA wires

    Science.gov (United States)

    Lei, KinFong; Yam, Yeung

    2000-06-01

    This work reports two modeling and control attempts performed on a positioning system comprising of linking SMA wires and an overlooking video system for on-line measurements. The first attempt takes the model by Ikuta and identifies experimentally the parameters of the SMA wire. The identified single wire model is then extended to a system of two SMA wires joining together at their tips, based upon which open loop position control of the linkage is then conducted. The approach, however, becomes too complicated when more SMA wires are involved. The second attempt utilizes a neuro-fuzzy based approach for positioning control of a linkage point joining together four SMA wires. The second approach involves four ANFIS neuro-networks with hybrid learning algorithm trained to model the currents to the SMA wires as functions of present and target positions of the linkage point. Experimentation for both the two-wires and four-wires system yield quite satisfactory performance.

  15. Percutaneous tension band wiring for patellar fractures.

    Science.gov (United States)

    Rathi, Akhilesh; Swamy, M K S; Prasantha, I; Consul, Ashu; Bansal, Abhishek; Bahl, Vibhu

    2012-08-01

    To evaluate outcome of percutaneous tension band wiring for transverse fractures of the patella. 16 men and 7 women aged 27 to 65 (mean, 40) years underwent percutaneous tension band wiring for transverse fractures of the patella with a displacement of >3 mm. Pain, operating time, mobility, functional score, and complications were evaluated. 20 patients underwent successful percutaneous tension band wiring. The remaining 3 patients in whom closed reduction failed underwent open reduction and tension band wiring. The mean operating time was 46 (range, 28-62) minutes. The mean follow-up period was 20 (range, 15-30) months. At the latest follow-up, all patients had regained full extension. The objective score was excellent in 20 patients and good in 3, whereas the subjective score was excellent in 17, good in 5, and fair in one. All patients had radiological union at week 8. One patient had patellofemoral arthritis (secondary to a postoperative articular step). Two patients developed superficial infections, which resolved after antibiotic therapy. Mean thigh muscle wasting was 0.7 (range, 0.4-1) cm. Three patients encountered hardware problems (impingement/irritation of the skin over the knee) necessitating implant removal. Percutaneous tension band wiring is a viable option for transverse fractures of the patella.

  16. EVALUATION OF INDUCTANCE WITH ELECTRICAL WIRES

    Directory of Open Access Journals (Sweden)

    V. Kudry

    2016-08-01

    Full Text Available In this paper proved the possibility of developing passive electronic inductive elements based replace metal wire that is wound inductor, the wire is made of electret. The relative permeability of the electret S  10 000, several orders of magnitude greater than the permeability of conventional insulation materials, i < 10, resulting current in the wire acquires properties bias current. The essence of innovation is to replace the source of of magnetic induction flow that pervades the core of the coil. According to the theory of electrodynamics, current bias, in contrast to conduction current, generated no movement of charge along the wire, but the change of the charge in the local volume.Equivalence bias current and conduction current is manifested in the possibility of forming a magnetic field. The flow through magnetic induction coil core regardless of the current it generates, creates voltage at its ends.The paper also shows the numeric characteristics that determine the effective frequency range, specified the reason why electric a wire with і < 10 can not generate magnetic flux through the core and serve as a passive reactive component.

  17. Wire scanner software and firmware issues

    Energy Technology Data Exchange (ETDEWEB)

    Gilpatrick, John Doug [Los Alamos National Laboratory

    2008-01-01

    The Los Alamos Neutron Science Center facility presently has 110 slow wire scanning profile measurement instruments located along its various beam lines. These wire scanners were developed and have been operating for at least 30 years. While the wire scanners solved many problems to operate and have served the facility well they have increasingly suffered from several problems or limitations, such as maintenance and reliability problems, antiquated components, slow data acquisition, and etc. In order to refurbish these devices, these wire scanners will be replaced with newer versions. The replacement will consist of a completely new beam line actuator, new cables, new electronics and brand new software and firmware. This note describes the functions and modes of operation that LabVIEW VI software on the real time controller and FPGA LabVIEW firmware will be required. It will be especially interesting to understand the overall architecture of these LabVIEW VIs. While this note will endeavor to describe all of the requirements and issues for the wire scanners, undoubtedly, there will be missing details that will be added as time progresses.

  18. The PS Booster Fast Wire Scanner

    CERN Document Server

    Burger, S; Priestnall, K; Raich, U

    2003-01-01

    The very tight emittance budget for LHC type beams makes precise emittance measurements in the injector complex a necessity. The PS machine uses 2 fast wire scanners per transverse plane for emittance measurement of the circulating beams. In order to ease comparison the same type of wire scanners have been newly installed in the upstream machine, the PS Booster, where each of the 4 rings is equipped with 2 wire scanners measuring the horizontal and vertical profiles. Those wire scanners use new and more modern control and readout electronics featuring dedicated intelligent motor movement controllers, which relieves the very stringent real time constraints due to the very high speed of 20m/s. In order to be able to measure primary beams at the very low injection energy of the Booster (50MeV) secondary emission currents from the wire can be measured as well as secondary particle flows at higher primary particle energies during and after acceleration. The solution adopted for the control of the devices is descri...

  19. Forgotten Kirschner Wire Causing Severe Hematuria

    Directory of Open Access Journals (Sweden)

    Santosh Kumar

    2014-01-01

    Full Text Available Kirschner wire (K-wire is commonly used in the treatment of hip fracture and its migration into pelvis leading to bladder injury is a very rare complication. Nonremoval of these devices either because of lack of followup or because of prolonged requirement due to disease process is associated with this complication. We report a case of a patient who presented with acute onset severe hematuria with clot retention secondary to perforation of bladder by a migrated K-wire placed earlier, for the treatment of hip fracture. Initial imaging showed its presence in the soft tissues of the pelvis away from the major vascular structures. Patient was taken for emergency laparotomy and wire was removed after cystotomy. Postoperative period was uneventful and patient was discharged in satisfactory condition. K-wires are commonly used in the management of fracture bones and their migration has been reported in the literature although such migration in the intrapelvic region involving bladder is very rare. Early diagnosis and prompt removal of such foreign bodies are required to avert potentially fatal involvement of major structures.

  20. Dynamics of Anderson localization in disordered wires

    Science.gov (United States)

    Khalaf, E.; Ostrovsky, P. M.

    2017-11-01

    We consider the dynamics of an electron in an infinite disordered metallic wire. We derive exact expressions for the probability of diffusive return to the starting point in a given time. The result is valid for wires with or without time-reversal symmetry and allows for the possibility of topologically protected conducting channels. In the absence of protected channels, Anderson localization leads to a nonzero limiting value of the return probability at long times, which is approached as a negative power of time with an exponent depending on the symmetry class. When topologically protected channels are present (in a wire of either unitary or symplectic symmetry), the probability of return decays to zero at long time as a power law whose exponent depends on the number of protected channels. Technically, we describe the electron dynamics by the one-dimensional supersymmetric nonlinear sigma model. We derive an exact identity that relates any local dynamical correlation function in a disordered wire of unitary, orthogonal, or symplectic symmetry to a certain expectation value in the random matrix ensemble of class AIII, CI, or DIII, respectively. The established exact mapping from a one- to a zero-dimensional sigma model is very general and can be used to compute any local observable in a disordered wire.

  1. Integrated Electrical Wire Insulation Repair System

    Science.gov (United States)

    Williams, Martha; Jolley, Scott; Gibson, Tracy; Parks, Steven

    2013-01-01

    An integrated system tool will allow a technician to easily and quickly repair damaged high-performance electrical wire insulation in the field. Low-melt polyimides have been developed that can be processed into thin films that work well in the repair of damaged polyimide or fluoropolymer insulated electrical wiring. Such thin films can be used in wire insulation repairs by affixing a film of this low-melt polyimide to the damaged wire, and heating the film to effect melting, flow, and cure of the film. The resulting repair is robust, lightweight, and small in volume. The heating of this repair film is accomplished with the use of a common electrical soldering tool that has been modified with a special head or tip that can accommodate the size of wire being repaired. This repair method can furthermore be simplified for the repair technician by providing replaceable or disposable soldering tool heads that have repair film already "loaded" and ready for use. The soldering tool heating device can also be equipped with a battery power supply that will allow its use in areas where plug-in current is not available

  2. Quantum computer games: quantum minesweeper

    Science.gov (United States)

    Gordon, Michal; Gordon, Goren

    2010-07-01

    The computer game of quantum minesweeper is introduced as a quantum extension of the well-known classical minesweeper. Its main objective is to teach the unique concepts of quantum mechanics in a fun way. Quantum minesweeper demonstrates the effects of superposition, entanglement and their non-local characteristics. While in the classical minesweeper the goal of the game is to discover all the mines laid out on a board without triggering them, in the quantum version there are several classical boards in superposition. The goal is to know the exact quantum state, i.e. the precise layout of all the mines in all the superposed classical boards. The player can perform three types of measurement: a classical measurement that probabilistically collapses the superposition; a quantum interaction-free measurement that can detect a mine without triggering it; and an entanglement measurement that provides non-local information. The application of the concepts taught by quantum minesweeper to one-way quantum computing are also presented.

  3. Quantum Physics Without Quantum Philosophy

    CERN Document Server

    Dürr, Detlef; Zanghì, Nino

    2013-01-01

    It has often been claimed that without drastic conceptual innovations a genuine explanation of quantum interference effects and quantum randomness is impossible. This book concerns Bohmian mechanics, a simple particle theory that is a counterexample to such claims. The gentle introduction and other contributions collected here show how the phenomena of non-relativistic quantum mechanics, from Heisenberg's uncertainty principle to non-commuting observables, emerge from the Bohmian motion of particles, the natural particle motion associated with Schrödinger's equation. This book will be of value to all students and researchers in physics with an interest in the meaning of quantum theory as well as to philosophers of science.

  4. Fractional Quantum Hall Plateau Transitions and Composite Fermi Liquids

    Science.gov (United States)

    Cho, Gil Young; Moon, Eun-Gook; Fradkin, Eduardo

    We will investigate relationship between the fractional quantum Hall plateau transition from Laughlin state at ν =1/2 n + 1 to a trivial insulator, and composite Fermi liquid at ν =1/2 (2 n + 1) . We use the recently-developed quantum field theoretic technique, 3d dualities, in combinations with the coupled-wire descriptions for quantum Hall states. We will show that we can also access various other phases, including non-abelian paired states at ν =1/2 (2 n + 1) , from the plateau transition. This work is supported by the Brain Korea 21 PLUS Project of Korea Government and KAIST start-up funding (GYC & EGM).

  5. Quantum Computing

    Science.gov (United States)

    Steffen, Matthias

    Solving computational problems require resources such as time, memory, and space. In the classical model of computation, computational complexity theory has categorized problems according to how difficult it is to solve them as the problem size increases. Remarkably, a quantum computer could solve certain problems using fundamentally fewer resources compared to a conventional computer, and therefore has garnered significant attention. Yet because of the delicate nature of entangled quantum states, the construction of a quantum computer poses an enormous challenge for experimental and theoretical scientists across multi-disciplinary areas including physics, engineering, materials science, and mathematics. While the field of quantum computing still has a long way to grow before reaching full maturity, state-of-the-art experiments on the order of 10 qubits are beginning to reach a fascinating stage at which they can no longer be emulated using even the fastest supercomputer. This raises the hope that small quantum computer demonstrations could be capable of approximately simulating or solving problems that also have practical applications. In this talk I will review the concepts behind quantum computing, and focus on the status of superconducting qubits which includes steps towards quantum error correction and quantum simulations.

  6. Quantum Finance

    Science.gov (United States)

    Baaquie, Belal E.

    2004-11-01

    Financial mathematics is currently almost completely dominated by stochastic calculus. Presenting a completely independent approach, this book applies the mathematical and conceptual formalism of quantum mechanics and quantum field theory (with particular emphasis on the path integral) to the theory of options and to the modeling of interest rates. Many new results, accordingly, emerge from the author's perspective.

  7. Quantum Entanglement in Double Quantum Systems and Jaynes-Cummings Model.

    Science.gov (United States)

    Jakubczyk, Paweł; Majchrowski, Klaudiusz; Tralle, Igor

    2017-12-01

    In the paper, we proposed a new approach to producing the qubits in electron transport in low-dimensional structures such as double quantum wells or double quantum wires (DQW). The qubit could arise as a result of quantum entanglement of two specific states of electrons in DQW structure. These two specific states are the symmetric and antisymmetric (with respect to inversion symmetry) states arising due to tunneling across the structure, while entanglement could be produced and controlled by means of the source of nonclassical light. We examined the possibility to produce quantum entanglement in the framework of Jaynes-Cummings model and have shown that at least in principle, the entanglement can be achieved due to series of "revivals" and "collapses" in the population inversion due to the interaction of a quantized single-mode EM field with a two-level system.

  8. Temperature Dependent Wire Delay Estimation in Floorplanning

    DEFF Research Database (Denmark)

    Winther, Andreas Thor; Liu, Wei; Nannarelli, Alberto

    2011-01-01

    Due to large variations in temperature in VLSI circuits and the linear relationship between metal resistance and temperature, the delay through wires of the same length can be different. Traditional thermal aware floorplanning algorithms use wirelength to estimate delay and routability....... In this work, we show that using wirelength as the evaluation metric does not always produce a floorplan with the shortest delay. We propose a temperature dependent wire delay estimation method for thermal aware floorplanning algorithms, which takes into account the thermal effect on wire delay. The experiment...... results show that a shorter delay can be achieved using the proposed method. In addition, we also discuss the congestion and reliability issues as they are closely related to routing and temperature....

  9. A new route to process diamond wires

    Directory of Open Access Journals (Sweden)

    Marcello Filgueira

    2003-06-01

    Full Text Available We propose an original route to process diamond wires, denominated In Situ Technology, whose fabrication involves mechanical conformation processes, such as rotary forging, copper tubes restacking, and thermal treatments, such as sintering and recrystallisation of a bronze 4 wt.% diamond composite. Tensile tests were performed, reaching an ultimate tensile strength (UTS of 230 MPa for the diameter of Æ = 1.84 mm. Scanning electron microscopy showed the diamond crystals distribution along the composite rope during its manufacture, as well as the diamond adhesion to the bronze matrix. Cutting tests were carried out with the processed wire, showing a probable performance 4 times higher than the diamond sawing discs, however its probable performance was about 5 to 8 times less than the conventional diamond wires (pearl system due to the low abrasion resistance of the bronze matrix, and low adhesion between the pair bronze-diamond due to the use of not metallised diamond single crystals.

  10. Magnetic wires in MEMS and bio-medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Barbic, Mladen E-mail: mladen@caltech.edu

    2002-08-01

    Magnetic wires of appropriate design have special features making them useful to micro-electromechanical systems and bio-medical applications. Several applications that exploit the properties of magnetic wires are reviewed including: (a) a magnetic micro-manipulation technique that utilizes integrated micro-coils and magnetic micro-wires for localized positioning of micron-sized magnetic objects, (b) integrated micro-coil/micro-wire system operating as a micro-fluidic micro-motor, (c) mechanical tweezers using magneto-static interaction between two magnetic micro-wires, and (d) ultra-high gradient magnetic separation system based on porous membranes partially filled with magnetic wires.

  11. Quantum gravity

    CERN Document Server

    Kiefer, Claus

    2012-01-01

    The search for a quantum theory of the gravitational field is one of the great open problems in theoretical physics. This book presents a self-contained discussion of the concepts, methods and applications that can be expected in such a theory. The two main approaches to its construction - the direct quantisation of Einstein's general theory of relativity and string theory - are covered. Whereas the first attempts to construct a viable theory for the gravitational field alone, string theory assumes that a quantum theory of gravity will be achieved only through a unification of all the interactions. However, both employ the general method of quantization of constrained systems, which is described together with illustrative examples relevant for quantum gravity. There is a detailed presentation of the main approaches employed in quantum general relativity: path-integral quantization, the background-field method and canonical quantum gravity in the metric, connection and loop formulations. The discussion of stri...

  12. Quantum mechanics

    CERN Document Server

    Rae, Alastair I M

    2016-01-01

    A Thorough Update of One of the Most Highly Regarded Textbooks on Quantum Mechanics Continuing to offer an exceptionally clear, up-to-date treatment of the subject, Quantum Mechanics, Sixth Edition explains the concepts of quantum mechanics for undergraduate students in physics and related disciplines and provides the foundation necessary for other specialized courses. This sixth edition builds on its highly praised predecessors to make the text even more accessible to a wider audience. It is now divided into five parts that separately cover broad topics suitable for any general course on quantum mechanics. New to the Sixth Edition * Three chapters that review prerequisite physics and mathematics, laying out the notation, formalism, and physical basis necessary for the rest of the book * Short descriptions of numerous applications relevant to the physics discussed, giving students a brief look at what quantum mechanics has made possible industrially and scientifically * Additional end-of-chapter problems with...

  13. Quantum photonics

    CERN Document Server

    Pearsall, Thomas P

    2017-01-01

    This textbook employs a pedagogical approach that facilitates access to the fundamentals of Quantum Photonics. It contains an introductory description of the quantum properties of photons through the second quantization of the electromagnetic field, introducing stimulated and spontaneous emission of photons at the quantum level. Schrödinger’s equation is used to describe the behavior of electrons in a one-dimensional potential. Tunneling through a barrier is used to introduce the concept of non­locality of an electron at the quantum level, which is closely-related to quantum confinement tunneling, resonant tunneling, and the origin of energy bands in both periodic (crystalline) and aperiodic (non-crystalline) materials. Introducing the concepts of reciprocal space, Brillouin zones, and Bloch’s theorem, the determination of electronic band structure using the pseudopotential method is presented, allowing direct computation of the band structures of most group IV, group III-V, and group II-VI semiconducto...

  14. Spin-dependent transport in epitaxial Fe wires on GaAs(110); Spinabhaengiger Transport in epitaktischen Fe-Leiterbahnen auf GaAs(110)

    Energy Technology Data Exchange (ETDEWEB)

    Hassel, Christoph

    2009-08-11

    In the present thesis, the spin dependent transport in epitaxial Fe wires as well as in perpendicularly magnetized multilayer wires is investigated. The main focus is on the investigation of quantum transport phenomena, the domain wall resistance as well as the current induced domain wall motion. Epitaxial Fe wires are prepared from epitaxial Fe films by means of electron beam lithography. Because of the intrinsic magnetic anisotropy, it is possible to prepare wires with a remanent transversal magnetization. Magnetic force microscopy is used to image the magnetic state of single wires. The magnetization reversal behaviour of these wires is investigated in detail using magnetoresistance measurements. These measurements are dominated by effects of the anisotropic magnetoresistance and can be explained by micromagnetic calculations. For the first time, quantum transport phenomena in epitaxial Fe wires are studied by magnetoresistance measurements for temperatures down to 20 mK. These measurements clearly indicate that, independent of the wire width and orientation, no contribution due to weak electron localization can be observed. The results are quantitatively explained within the framework of enhanced electron-electron interactions. Furthermore, by reducing the wire width the onset of the transition from two-dimensional to one-dimensional behaviour is found. To determine the domain wall resistance, a different number of domain walls is created in various structures, whereby the epitaxial samples allow to investigate different domain wall structures. First, a technique based on the stray field of a magnetic force microscope tip is presented. Furthermore, the influence of the shape anisotropy on the coercive field of single wires is used. Contributions to the observed resistance change due to the anisotropic magnetoresistance are calculated using micromagnetic simulations. A positive intrinsic relative resistance increase of 0.2% within the domain wall is found at

  15. Laser wire emittance measurement line AT CLIC

    CERN Document Server

    Garcia, H; Blair, G A; Aumeyr, T; Schulte, D; Stulle, F

    2011-01-01

    A precise measurement of the transverse beam size and beam emittances upstream of the final focus is essential for ensuring the full luminosity at future linear colliders. A scheme for the emittance measurements at the RTML line of the CLIC using laser-wire beam profile monitors is described. A lattice of the measurement line is discussed and results of simulations of statistical errors and of their impact on the accuracy of the emittance reconstruction are given. Laser wire systems suitable for CLIC and their main characteristics are discussed.

  16. Transient response of wire bicone antennas

    Science.gov (United States)

    Morgan, J. G.; Lizius, D. W.

    This paper describes the computational analysis of biconical wire antennas without end-caps performed using an extended and improved version of the Thin Wire Time Domain code from the Lawrence Livermore National Laboratory. Special attention is given to the computational algorithm used in the direct time domain analysis of the transient behavior of antennas. It is shown that the time domain numerical predictions are consistent with intuitive expectations and with predictions obtained from the Fourier transform of a frequency domain semianalytical model of a sheet bicone antenna.

  17. Numerical Simulation of Wire-Coating

    DEFF Research Database (Denmark)

    Wapperom, Peter; Hassager, Ole

    1999-01-01

    A finite element program has been used to analyze the wire-coating process of an MDPE melt. The melt is modeled by a nonisothermal Carreau model. The emphasis is on predicting an accurate temperature field. Therefore, it is necessary to include the heat conduction in the metal parts. A comparison...... is made with the results of a simulation that models the heat conduction in the metal head by means of a Biot boundary condition. The influence of the wire velocity, inlet temperature and power-law index will be examined....

  18. EDITORIAL More than a wire More than a wire

    Science.gov (United States)

    Demming, Anna

    2010-10-01

    Nanowires are the natural evolution of the connections in circuits when scaled down to nanometre sizes. On closer inspection, of course, the role of nanowires in developing new technologies is much more than just a current-bearing medium. By sizing the diameters of these objects down to the nanoscale, their properties become increasingly sensitive to factors such as the gas composition, temperature and incident light of their surrounding environment, as well as defects and variations in diameter. What becomes important in modern electronics innovations is not just what is connected, but how. Nanowires had already begun to attract the attention of researchers in the early 1990s as advances in imaging and measurement devices invited researchers to investigate the properties of these one-dimensional structures [1, 2]. This interest has sparked ingenious ways of fabricating nanowires such as the use of a DNA template. A collaboration of researchers at Louisiana Tech University in the US hs provided an overview of various methods to assemble conductive nanowires on a DNA template, including a summary of different approaches to stretching and positioning the templates [3]. Work in this area demonstrates a neat parallel for the role of DNA molecules as the building blocks of life and the foundations of nanoscale device architectures. Scientists at HP Labs in California are using nanowires to shrink the size of logic arrays [4]. One aspect of electronic interconnects that requires particular attention at nanoscale sizes is the effect of defects. The researchers at HP Labs demonstrate that their approach, which they name FPNI (field-programmable nanowire interconnect), is extremely tolerant of the high defect rates likely to be found in these nanoscale structures, and allows reduction in size and power without significantly sacrificing the clock rate. Another issue in scaling down electronics is the trend for an increasing resistivity with decreasing wire width. Researchers

  19. Scalable designs for quasiparticle-poisoning-protected topological quantum computation with Majorana zero modes

    Science.gov (United States)

    Karzig, Torsten; Knapp, Christina; Lutchyn, Roman M.; Bonderson, Parsa; Hastings, Matthew B.; Nayak, Chetan; Alicea, Jason; Flensberg, Karsten; Plugge, Stephan; Oreg, Yuval; Marcus, Charles M.; Freedman, Michael H.

    2017-06-01

    We present designs for scalable quantum computers composed of qubits encoded in aggregates of four or more Majorana zero modes, realized at the ends of topological superconducting wire segments that are assembled into superconducting islands with significant charging energy. Quantum information can be manipulated according to a measurement-only protocol, which is facilitated by tunable couplings between Majorana zero modes and nearby semiconductor quantum dots. Our proposed architecture designs have the following principal virtues: (1) the magnetic field can be aligned in the direction of all of the topological superconducting wires since they are all parallel; (2) topological T junctions are not used, obviating possible difficulties in their fabrication and utilization; (3) quasiparticle poisoning is abated by the charging energy; (4) Clifford operations are executed by a relatively standard measurement: detection of corrections to quantum dot energy, charge, or differential capacitance induced by quantum fluctuations; (5) it is compatible with strategies for producing good approximate magic states.

  20. Resonant tunneling quantum waveguides of variable cross-section, asymptotics, numerics, and applications

    CERN Document Server

    Baskin, Lev; Plamenevskii, Boris; Sarafanov, Oleg

    2015-01-01

    This volume studies electron resonant tunneling in two- and three-dimensional quantum waveguides of variable cross-sections in the time-independent approach. Mathematical models are suggested for the resonant tunneling and develop asymptotic and numerical approaches for investigating the models. Also, schemes are presented for several electronics devices based on the phenomenon of resonant tunneling.   Devices based on the phenomenon of electron resonant tunneling are widely used in electronics. Efforts are directed towards refining properties of resonance structures. There are prospects for building new nanosize electronics elements based on quantum dot systems.   However, the role of resonance structure can also be given to a quantum wire of variable cross-section. Instead of an "electrode - quantum dot - electrode" system, one can use a quantum wire with two narrows. A waveguide narrow is an effective potential barrier for longitudinal electron motion along a waveguide. The part of the waveguide between ...

  1. Wire grid polarizers for visible wavelengths

    Science.gov (United States)

    Johnson, Joshua Hans

    Detailed analysis of wire-grid (WG) polarizers for visible wavelengths is presented. Rigorous coupled-wave analysis (RCWA) is used to model their performance. The optimum choice of metal for the wires is identified, and the effects of different substrate indices of refraction are considered. The polarization properties are considered with changes in the physical parameters, including period, duty cycle, and wire thickness. It is shown that the performance of WG polarizers improves with increasing angle of incidence. The effect of non-square wire profiles is considered, as is the effect of adding additional dielectric layers between the wires and the substrate. The effect of metal oxide layers forming on the wires is also modeled. While most of this work concerns WG polarizers used in transmission, the performance in reflection is also discussed. Several visible-wavelength WG polarizers were fabricated at the Cornell Nanofabrication Facility (CNF) in Ithaca, NY. Electron-beam lithography was used to write the patterns for these devices, and two different methods of pattern transfer were compared. These were the lift-off method and reactive-ion etching (RIE). We found that lift-off could not produce wires thick enough for good polarization properties. RIE could produce much thicker wires with good profiles and was used for all of the experimental work presented here. Two different methods for metal film deposition, evaporation and sputtering were also compared. Films deposited by sputtering were found to have much lower indices of refraction and to not respond to etching as well. Thermally evaporated films performed much better in WG polarizers. Alternative methods for the mass-production of visible-wavelength WG polarizers are also discussed. The performance of the fabricated WG polarizers is compared to theory. When the measured physical parameters are used in RCWA to predict the performance, the measured extinction ratio is found to be much lower than the

  2. Quantum communications

    CERN Document Server

    Cariolaro, Gianfranco

    2015-01-01

    This book demonstrates that a quantum communication system using the coherent light of a laser can achieve performance orders of magnitude superior to classical optical communications Quantum Communications provides the Masters and PhD signals or communications student with a complete basics-to-applications course in using the principles of quantum mechanics to provide cutting-edge telecommunications. Assuming only knowledge of elementary probability, complex analysis and optics, the book guides its reader through the fundamentals of vector and Hilbert spaces and the necessary quantum-mechanical ideas, simply formulated in four postulates. A turn to practical matters begins with and is then developed by: ·         development of the concept of quantum decision, emphasizing the optimization of measurements to extract useful information from a quantum system; ·         general formulation of a transmitter–receiver system ·         particular treatment of the most popular quantum co...

  3. Quantum Computers and Quantum Computer Languages: Quantum Assembly Language and Quantum C

    OpenAIRE

    Blaha, Stephen

    2002-01-01

    We show a representation of Quantum Computers defines Quantum Turing Machines with associated Quantum Grammars. We then create examples of Quantum Grammars. Lastly we develop an algebraic approach to high level Quantum Languages using Quantum Assembly language and Quantum C language as examples.

  4. Quantum Computers and Quantum Computer Languages: Quantum Assembly Language and Quantum C Language

    OpenAIRE

    Blaha, Stephen

    2002-01-01

    We show a representation of Quantum Computers defines Quantum Turing Machines with associated Quantum Grammars. We then create examples of Quantum Grammars. Lastly we develop an algebraic approach to high level Quantum Languages using Quantum Assembly language and Quantum C language as examples.

  5. Picturing Quantum Processes

    Science.gov (United States)

    Coecke, Bob; Kissinger, Aleks

    2017-03-01

    Preface; 1. Introduction; 2. Guide to reading this textbook; 3. Processes as diagrams; 4. String diagrams; 5. Hilbert space from diagrams; 6. Quantum processes; 7. Quantum measurement; 8. Picturing classical-quantum processes; 9. Picturing phases and complementarity; 10. Quantum theory: the full picture; 11. Quantum foundations; 12. Quantum computation; 13. Quantum resources; 14. Quantomatic; Appendix A. Some notations; References; Index.

  6. Quantum Cryptography Beyond Quantum Key Distribution

    OpenAIRE

    Broadbent, A.; Schaffner, C

    2015-01-01

    textabstractQuantum cryptography is the art and science of exploiting quantum mechanical effects in order to perform cryptographic tasks. While the most well-known example of this discipline is quantum key distribution (QKD), there exist many other applications such as quantum money, randomness generation, secure two- and multi-party computation and delegated quantum computation. Quantum cryptography also studies the limitations and challenges resulting from quantum adversaries—including the ...

  7. Quantum simulations with circuit quantum electrodynamics

    OpenAIRE

    Romero, G.; Solano, E.; Lamata, L.

    2016-01-01

    Superconducting circuits have become a leading quantum technology for testing fundamentals of quantum mechanics and for the implementation of advanced quantum information protocols. In this chapter, we revise the basic concepts of circuit network theory and circuit quantum electrodynamics for the sake of digital and analog quantum simulations of quantum field theories, relativistic quantum mechanics, and many-body physics, involving fermions and bosons. Based on recent improvements in scalabi...

  8. Negative differential resistance in a one-dimensional molecular wire ...

    Indian Academy of Sciences (India)

    voltage characteristics of a one-dimensional molecular wire with odd number of atoms. The wire has been modelled ... Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560 064, India ...

  9. Radiation of relativistic electrons in a periodic wire structure

    Energy Technology Data Exchange (ETDEWEB)

    Soboleva, V.V., E-mail: sobolevaveronica@mail.ru; Naumenko, G.A.; Bleko, V.V.

    2015-07-15

    We present in this work the experimental investigation of the interaction of relativistic electron field with periodic wire structures. We used two types of the targets in experiments: flat wire target and sandwich wire target that represent the right triangular prism. The measurements were done in millimeter wavelength region (10–40 mm) on the relativistic electron beam with energy of 6.2 MeV in far-field zone. We showed that bunched electron beam passing near wire metamaterial prism generates coherent Cherenkov radiation. The experiments with flat wire target were carried out in two geometries. In the first geometry the electron beam passed close to the flat wire target surface. In the second case the electron beam passed through the flat wire structure with generation of a coherent backward transition radiation (CBTR). The comparison of the Cherenkov radiation intensity and BTR intensity from the flat wire target and from the flat conductive target (conventional BTR) was made.

  10. Electric and Magnetic Forces between Parallel-Wire Conductors.

    Science.gov (United States)

    Morton, N.

    1979-01-01

    Discusses electric and magnetic forces between parallel-wire conductors and derives, in a simple fashion, order of magnitude estimates of the ratio of the likely electrostatic and electromagnetic forces for a simple parallel-wire balance. (Author/HM)

  11. Fluctuation theorem in quantum heat conduction.

    Science.gov (United States)

    Saito, Keiji; Dhar, Abhishek

    2007-11-02

    We consider steady-state heat conduction across a quantum harmonic chain connected to reservoirs modeled by infinite collection of oscillators. The heat, Q, flowing across the oscillator in a time interval tau is a stochastic variable and we study the probability distribution function P(Q). We compute the exact generating function of Q at large tau and the large deviation function. The generating function has a symmetry satisfying the steady-state fluctuation theorem without any quantum corrections. The distribution P(Q) is non-Gaussian with clear exponential tails. The effect of finite tau and nonlinearity is considered in the classical limit through Langevin simulations. We also obtain the prediction of quantum heat current fluctuations at low temperatures in clean wires.

  12. Ising quantum criticality in Majorana nanowires

    Science.gov (United States)

    Cole, William S.; Sau, Jay D.; Das Sarma, S.

    2017-10-01

    Finite-length one-dimensional topological superconductor wires host localized Majorana zero modes at their ends. In realistic models, these appear only after a topological quantum critical point is crossed by external tuning of parameters. Thus, there is a universal finite-size scaling, governed by the critical point, that dictates the evolution of the energy of the Majorana modes near the transition. We first describe this scaling, then apply it in detail to an explicit synthetic topological superconductor model. Our work not only connects Ising quantum criticality with realistic nanowires in the presence of spin-orbit coupling, Zeeman splitting, and superconductivity, but also provides a viable experimental route for discerning the existence of the topological quantum critical point.

  13. Quantum mechanics

    CERN Document Server

    Powell, John L

    2015-01-01

    Suitable for advanced undergraduates, this thorough text focuses on the role of symmetry operations and the essentially algebraic structure of quantum-mechanical theory. Based on courses in quantum mechanics taught by the authors, the treatment provides numerous problems that require applications of theory and serve to supplement the textual material.Starting with a historical introduction to the origins of quantum theory, the book advances to discussions of the foundations of wave mechanics, wave packets and the uncertainty principle, and an examination of the Schrödinger equation that includ

  14. Quantum chemistry

    CERN Document Server

    Lowe, John P

    1993-01-01

    Praised for its appealing writing style and clear pedagogy, Lowe's Quantum Chemistry is now available in its Second Edition as a text for senior undergraduate- and graduate-level chemistry students. The book assumes little mathematical or physical sophistication and emphasizes an understanding of the techniques and results of quantum chemistry, thus enabling students to comprehend much of the current chemical literature in which quantum chemical methods or concepts are used as tools. The book begins with a six-chapter introduction of standard one-dimensional systems, the hydrogen atom,

  15. Quantum mechanics

    CERN Document Server

    Chowdhury, Sujaul

    2014-01-01

    This book presents comprehensive account of the course for undergraduate students with thorough and complete calculations. The book has been written with the notion that a wave is associated with a material particle i.e. wave and particle coexist. Heisenberg's uncertainty principle has been described in light of this. A chapter is dedicated to mathematical structure of Quantum Mechanics followed by applications to one-dimensional (1D) problems. Orbital and general angular momentum are treated in two separate chapters, the latter also treats addition of angular momentum. Quantum theory of scattering, matrix formulation of Quantum Mechanics variational method and WKB approximation method have also been discussed.

  16. Quantum algorithmic information theory

    OpenAIRE

    Svozil, Karl

    1995-01-01

    The agenda of quantum algorithmic information theory, ordered `top-down,' is the quantum halting amplitude, followed by the quantum algorithmic information content, which in turn requires the theory of quantum computation. The fundamental atoms processed by quantum computation are the quantum bits which are dealt with in quantum information theory. The theory of quantum computation will be based upon a model of universal quantum computer whose elementary unit is a two-port interferometer capa...

  17. Studying superconducting Nb3Sn wire

    CERN Multimedia

    AUTHOR|(CDS)2099575

    2015-01-01

    Studying superconducting Nb3Sn wire. From the current experience from LHC and HL-LHC we know that the performance requirements for Nb3Sn conductor for future circular collider are challenging and should exceed that of present state-of-the-art materials.

  18. Niobium Titanium and Copper wire samples

    CERN Document Server

    2009-01-01

    Two wire samples, both for carrying 13'000Amperes. I sample is copper. The other is the Niobium Titanium wiring used in the LHC magnets. The high magnetic fields needed for guiding particles around the Large Hadron Collider (LHC) ring are created by passing 12’500 amps of current through coils of superconducting wiring. At very low temperatures, superconductors have no electrical resistance and therefore no power loss. The LHC is the largest superconducting installation ever built. The magnetic field must also be extremely uniform. This means the current flowing in the coils has to be very precisely controlled. Indeed, nowhere before has such precision been achieved at such high currents. Magnet coils are made of copper-clad niobium–titanium cables — each wire in the cable consists of 9’000 niobium–titanium filaments ten times finer than a hair. The cables carry up to 12’500 amps and must withstand enormous electromagnetic forces. At full field, the force on one metre of magnet is comparable ...

  19. Description of CBETA magnet tuning wire holders

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, S. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-07-19

    A non-­magnetic insert will be placed directly inside the permanent magnet blocks in every CBETA Halbach magnet in order to hold a set of iron “tuning wires”. These wires have various lengths around the perimeter of the aperture in order to cancel multipole field errors from the permanent magnet blocks.

  20. Wire Separation From Automotive Shredder Residue

    NARCIS (Netherlands)

    Fabrizi, L.; De Jong, T.P.R.; Bevilacqua, P.

    2003-01-01

    The investigation discussed in this article concerned the removal of wires and cables fraction contained in automotive shredder residue (ASR) through a newly invented device, called the nail roll. Series of tests were carried out with three ASR samples of different origin and the influence of the

  1. Commercial and Industrial Wiring. Second Edition.

    Science.gov (United States)

    Kaltwasser, Stan; Flowers, Gary

    This guide is designed to assist teachers conducting a course to prepare students for entry-level employment in the commercial and industrial wiring trade. Included in the guide are 15 instructional units and the following sections of information for teachers: guidelines in using the unit components; academic and workplace skills classifications…

  2. Readout system for proportional wire chambers

    CERN Document Server

    Berst, J D; Metzger, G; Meyer, J M; Schultz, G

    1974-01-01

    The authors describe a MWPC read-out system intended for the hyperon experiments at CERN. Its structure is like the familiar CAMAC branch highway, but driven by a spark chamber readout module placed in CAMAC. The different parts of the equipment, which may read up to 4096 wires, and the test system are described. (5 refs).

  3. SRB Altitude Switch Assembly Wire Harness Failure

    Science.gov (United States)

    Blanche, Jim

    2002-01-01

    This paper presents an assessment of two wire harness failures that had occurred in Solid Rocket Booster Altitude Switch Assemblies S/N 200001 and S/N 20002. A list of modifications to EDU #4 and modification of qualification units 2000001 and 2000002 are also presented.

  4. Diamagnetism in wire medium metamaterials: Theory and experiment

    Science.gov (United States)

    Yagupov, I.; Filonov, D.; Ageyskiy, A.; Kosulnikov, S.; Hasan, M.; Iorsh, I. V.; Belov, P. A.

    2015-07-01

    A strong diamagnetic response of a wire medium with a finite wire radius is reported. Contrary to the previous works where it was assumed that the wire medium exhibits only an electric response, we show that the nonzero magnetic susceptibility has to be taken into account for a proper effective medium description of the wire medium. Analytical and numerical results are supported by experimental measurements.

  5. A notch-wire composite antenna for polarization diversity reception

    OpenAIRE

    Kuga, Nobuhiro; Arai, H; Goto, N

    1998-01-01

    This paper presents a notch-wire composite antenna for polarization diversity reception in an indoor base-station system, A three-notched disk antenna and a wire antenna are proposed as component antennas for the horizontal and the vertical polarization, respectively. These component antennas are unified as a single composite diversity antenna by mounting the wire antenna on the notched disk. Antenna characteristics are calculated using the method of moments (MoM) with wire grid models and ex...

  6. The operator tensor formulation of quantum theory.

    Science.gov (United States)

    Hardy, Lucien

    2012-07-28

    In this paper, we provide what might be regarded as a manifestly covariant presentation of discrete quantum theory. A typical quantum experiment has a bunch of apparatuses placed so that quantum systems can pass between them. We regard each use of an apparatus, along with some given outcome on the apparatus (a certain detector click or a certain meter reading for example), as an operation. An operation (e.g. B(b(2)a(3))(a(1))) can have zero or more quantum systems inputted into it and zero or more quantum systems outputted from it. The operation B(b(2)a(3))(a(1)) has one system of type a inputted, and one system of type b and one system of type a outputted. We can wire together operations to form circuits, for example, A(a(1))B(b(2)a(3))(a(1))C(b(2)a(3)). Each repeated integer label here denotes a wire connecting an output to an input of the same type. As each operation in a circuit has an outcome associated with it, a circuit represents a set of outcomes that can happen in a run of the experiment. In the operator tensor formulation of quantum theory, each operation corresponds to an operator tensor. For example, the operation B(b(2)a(3))(a(1)) corresponds to the operator tensor B(b(2)a(3))(a(1)). Further, the probability for a general circuit is given by replacing operations with corresponding operator tensors as in Prob(A(a(1))B(b(2)a(3))(a(1))C(b(2)a(3))) = Â(a(1))B(b(2)a(3))(a(1))C(b(2)a(3)). Repeated integer labels indicate that we multiply in the associated subspace and then take the partial trace over that subspace. Operator tensors must be physical (namely, they must have positive input transpose and satisfy a certain normalization condition).

  7. A Practical Phase Gate for Producing Bell Violations in Majorana Wires

    Directory of Open Access Journals (Sweden)

    David J. Clarke

    2016-04-01

    Full Text Available Carrying out fault-tolerant topological quantum computation using non-Abelian anyons (e.g., Majorana zero modes is currently an important goal of worldwide experimental efforts. However, the Gottesman-Knill theorem [1] holds that if a system can only perform a certain subset of available quantum operations (i.e., operations from the Clifford group in addition to the preparation and detection of qubit states in the computational basis, then that system is insufficient for universal quantum computation. Indeed, any measurement results in such a system could be reproduced within a local hidden variable theory, so there is no need for a quantum-mechanical explanation and therefore no possibility of quantum speedup [2]. Unfortunately, Clifford operations are precisely the ones available through braiding and measurement in systems supporting non-Abelian Majorana zero modes, which are otherwise an excellent candidate for topologically protected quantum computation. In order to move beyond the classically simulable subspace, an additional phase gate is required. This phase gate allows the system to violate the Bell-like Clauser-Horne-Shimony-Holt (CHSH inequality that would constrain a local hidden variable theory. In this article, we introduce a new type of phase gate for the already-existing semiconductor-based Majorana wire systems and demonstrate how this phase gate may be benchmarked using CHSH measurements. We present an experimentally feasible schematic for such an experiment using a “measurement-only” approach that bypasses the need for explicit Majorana braiding. This approach may be scaled beyond the two-qubit system necessary for CHSH violations, leading to a well-defined platform for universal fault-tolerant quantum computation using Majorana zero modes.

  8. Communication and wiring in the cortical connectome

    Science.gov (United States)

    Budd, Julian M. L.; Kisvárday, Zoltán F.

    2012-01-01

    In cerebral cortex, the huge mass of axonal wiring that carries information between near and distant neurons is thought to provide the neural substrate for cognitive and perceptual function. The goal of mapping the connectivity of cortical axons at different spatial scales, the cortical connectome, is to trace the paths of information flow in cerebral cortex. To appreciate the relationship between the connectome and cortical function, we need to discover the nature and purpose of the wiring principles underlying cortical connectivity. A popular explanation has been that axonal length is strictly minimized both within and between cortical regions. In contrast, we have hypothesized the existence of a multi-scale principle of cortical wiring where to optimize communication there is a trade-off between spatial (construction) and temporal (routing) costs. Here, using recent evidence concerning cortical spatial networks we critically evaluate this hypothesis at neuron, local circuit, and pathway scales. We report three main conclusions. First, the axonal and dendritic arbor morphology of single neocortical neurons may be governed by a similar wiring principle, one that balances the conservation of cellular material and conduction delay. Second, the same principle may be observed for fiber tracts connecting cortical regions. Third, the absence of sufficient local circuit data currently prohibits any meaningful assessment of the hypothesis at this scale of cortical organization. To avoid neglecting neuron and microcircuit levels of cortical organization, the connectome framework should incorporate more morphological description. In addition, structural analyses of temporal cost for cortical circuits should take account of both axonal conduction and neuronal integration delays, which appear mostly of the same order of magnitude. We conclude the hypothesized trade-off between spatial and temporal costs may potentially offer a powerful explanation for cortical wiring patterns

  9. Quantum computers.

    Science.gov (United States)

    Ladd, T D; Jelezko, F; Laflamme, R; Nakamura, Y; Monroe, C; O'Brien, J L

    2010-03-04

    Over the past several decades, quantum information science has emerged to seek answers to the question: can we gain some advantage by storing, transmitting and processing information encoded in systems that exhibit unique quantum properties? Today it is understood that the answer is yes, and many research groups around the world are working towards the highly ambitious technological goal of building a quantum computer, which would dramatically improve computational power for particular tasks. A number of physical systems, spanning much of modern physics, are being developed for quantum computation. However, it remains unclear which technology, if any, will ultimately prove successful. Here we describe the latest developments for each of the leading approaches and explain the major challenges for the future.

  10. Quantum Computation

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 9. Quantum Computation - Particle and Wave Aspects of Algorithms. Apoorva Patel. General Article Volume 16 ... Keywords. Boolean logic; computation; computational complexity; digital language; Hilbert space; qubit; superposition; Feynman.

  11. 30 CFR 77.705 - Guy wires; grounding.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Guy wires; grounding. 77.705 Section 77.705... MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Grounding § 77.705 Guy wires; grounding. Guy wires from poles supporting high-voltage transmission lines shall be...

  12. 49 CFR 236.723 - Circuit, double wire; line.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Circuit, double wire; line. 236.723 Section 236.723 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... § 236.723 Circuit, double wire; line. An electric circuit not employing a common return wire; a circuit...

  13. Thermal Aware Floorplanning Incorporating Temperature Dependent Wire Delay Estimation

    DEFF Research Database (Denmark)

    Winther, AndreasThor; Liu, Wei; Nannarelli, Alberto

    2015-01-01

    Temperature has a negative impact on metal resistance and thus wire delay. In state-of-the-art VLSI circuits, large thermal gradients usually exist due to the uneven distribution of heat sources. The difference in wire temperature can lead to performance mismatch because wires of the same length ...

  14. 78 FR 7452 - Steel Wire Garment Hangers From Vietnam; Determinations

    Science.gov (United States)

    2013-02-01

    ... COMMISSION Steel Wire Garment Hangers From Vietnam; Determinations On the basis of the record \\1\\ developed... imports of steel wire garment hangers from Vietnam, provided for in subheading 7326.20.00 of the... countervailing and antidumping duty orders on steel wire garment hangers from Vietnam. Background The Commission...

  15. Basic Wiring. Third Edition. Teacher Edition [and] Student Edition.

    Science.gov (United States)

    Kaltwasser, Stan; Flowers, Gary; Blasingame, Don; Batson, Larry; Ipock, Dan; Carroll, Charles; Friesen, Wade; Fleming, Glenn

    This publication contains both a teacher edition and a student edition of materials for a foundation course in an electrical wiring program. The course introduces basic concepts and skills that are prerequisites to residential wiring and commercial and industrial wiring courses. The contents of the materials are tied to measurable and observable…

  16. Lunar Module Wiring Design Considerations and Failure Modes

    Science.gov (United States)

    Interbartolo, Michael

    2009-01-01

    This slide presentation reviews the considerations for the design of wiring for the Lunar Module. Included are a review of the choice of conductors and insulations, the wire splicing (i.e., crimping, and soldering), the wire connectors, and the fabrication of the wire harnesses. The problems in fabrication include the wires being the wrong length, the damage due to the sharp edges, the requried use of temproary protective covers and inadequate training. The problems in the wire harness installation include damge from sharp eges, work on adjacent harnesses, connector damage, and breaking wires. Engineering suggestions from the Apollo-era in reference to the conductors that are reviewed include: the use of plated conductors, and the use of alloys for stronger wiring. In refernce to insulation, the suggestions from Apollo era include the use of polymer tape-wrap wire insulation due to the light weight, however, other types of modern insulation might be more cost-effective. In reference to wire splices and terminal boards the suggestions from the Apollo Era include the use of crimp splices as superior to solder splices, joining multiple wire to a common point using modular plug-ins might be more reliable, but are heavier than crimp splicing. For connectors, the lessons from the Apollo era indicate that a rear environmental seal that does not require additional potting is preferred, and pins should be crimped or welded to the incoming wires and be removable from the rear of the connector.

  17. Filler-wire positioner for electron beam welding

    Science.gov (United States)

    Beaupre, W. M.; Fueg, L. B.; Phillips, J. A.

    1970-01-01

    Miniaturized positioner is installed in any electron beam vacuum chamber for use with wire feed applications requiring filler wire. Horizontal and vertical control of the positioner is maintained from a console while chamber is under vacuum. Device permits more positive positioning of welding filler wire.

  18. 77 FR 1504 - Stainless Steel Wire Rod From India

    Science.gov (United States)

    2012-01-10

    ... COMMISSION Stainless Steel Wire Rod From India Determination On the basis of the record \\1\\ developed in the... antidumping duty order on stainless steel wire rod From India would be likely to lead to continuation or... contained in USITC Publication 4300 (January 2012), entitled Stainless Steel Wire Rod From India...

  19. Kirschner Wires : insertion techniques and bone related consequences

    NARCIS (Netherlands)

    Franssen, B.B.G.M.

    2010-01-01

    The Kirschner (K-) wire was first introduced in 1909 by Martin Kirschner. This is a thin unthreaded wire of surgical steel with a diameter of up to three millimeters and a selection of different tips. The use of K-wires is often promoted as a simple technique because of its easy placement,

  20. Modeling, simulation and parametric optimization of wire EDM ...

    African Journals Online (AJOL)

    In the present work, quadratic mathematical models have been derived to represent the process behavior of wire electrical discharge machining (WEDM) operation. Experiments have been conducted with six process parameters: discharge current, pulse duration, pulse frequency, wire speed, wire tension and dielectric flow ...

  1. Experimental investigation of industrial copper deformed by wire ...

    African Journals Online (AJOL)

    drawing on microstructure and physical properties of industrial copper wires. Copper wires were provided by E.N.I.CA.Biskra (Algeria). We investigated some wires with different strain levels (as received, 1.20, 2.10, and ε = 3.35).

  2. Application of Matteucci Voltage Pulses of Amorphous Wires in ...

    African Journals Online (AJOL)

    In this work the effect of torsion on the Matteucci voltage pulses in amorphous wires has been studied. It has been shown that: Amplitude of the pulses decreases to zero at a twist angle that depends on the chemical composition of the wire. From zero torsion, the amplitude of the Matteucci voltage increases when the wires ...

  3. 77 FR 28404 - Galvanized Steel Wire From China and Mexico

    Science.gov (United States)

    2012-05-14

    ... COMMISSION Galvanized Steel Wire From China and Mexico Determinations On the basis of the record \\1... retarded, by reason of imports from China of galvanized steel wire, provided for in subheadings 7217.20.30... retarded, by reason of imports from Mexico of galvanized steel wire, provided for in subheadings 7217.20.30...

  4. 76 FR 29266 - Galvanized Steel Wire From China and Mexico

    Science.gov (United States)

    2011-05-20

    ... COMMISSION Galvanized Steel Wire From China and Mexico Determinations On the basis of the record \\1... injured by reason of imports from China and Mexico of galvanized steel wire, provided for in subheading... subsidized imports of galvanized steel wire from China and Mexico. Accordingly, effective March 31, 2011, the...

  5. Asymmetric GaAs/AlGaAs T wires with large confinement energies

    DEFF Research Database (Denmark)

    Gislason, Hannes; Langbein, Wolfgang Werner; Hvam, Jørn Märcher

    1996-01-01

    We report on the design and growth of asymmetric T-shaped quantum wires with large one-dimensional confinement energies. Prior to growth, the optimal structure for a given (110) well width is determined by a calculation, The structures are made by molecular beam epitaxy cleaved edge overgrowth. We...... demonstrate a confinement of 53 meV in an experimental structure consisting of a narrow (110) oriented GaAs/Al0.3Ga0.7As quantum well overgrown on much wider(001) oriented Al0.14Ga0.86As/Al0.3Ga0.7As wells. (C) 1996 American Institute of Physics....

  6. Delayed migration of K-wire into popliteal fossa used for tension band wiring of patellar fracture

    Directory of Open Access Journals (Sweden)

    Meena Sanjay

    2013-06-01

    Full Text Available 【Abstract】Breakage of K-wires and stainless steel wires which are used for fracture fixation is not uncommon, but migration is rare. We report a case of migration of bro-ken K-wire used for patella tension band wiring to the popliteal fossa. The broken hardware was removed surgically. We would like to suggest that K-wire and wire fixation used for treatment of patellar fractures can migrate into the posterior compartment of the knee and cause clini-cal symptoms. Close clinical and radiological follow-up af-ter internal fixation to identify the presence of hardware breakage or movement and removal of wires once fracture has united can avert such complications. Key words: Patella; Fracture fixation, internal; Bone wires

  7. On grouping individual wire segments into equivalent wires or chains, and introduction of multiple domain basis functions

    CSIR Research Space (South Africa)

    Lysko, AA

    2009-06-01

    Full Text Available The paper introduces a method to cover several wire segments with a single basis function, describes related practical algorithms, and gives some results. The process involves three steps: identifying chains of wire segments, splitting the chains...

  8. Quantum correlations and distinguishability of quantum states

    Energy Technology Data Exchange (ETDEWEB)

    Spehner, Dominique [Université Grenoble Alpes and CNRS, Institut Fourier, F-38000 Grenoble, France and Laboratoire de Physique et Modélisation des Milieux Condensés, F-38000 Grenoble (France)

    2014-07-15

    A survey of various concepts in quantum information is given, with a main emphasis on the distinguishability of quantum states and quantum correlations. Covered topics include generalized and least square measurements, state discrimination, quantum relative entropies, the Bures distance on the set of quantum states, the quantum Fisher information, the quantum Chernoff bound, bipartite entanglement, the quantum discord, and geometrical measures of quantum correlations. The article is intended both for physicists interested not only by collections of results but also by the mathematical methods justifying them, and for mathematicians looking for an up-to-date introductory course on these subjects, which are mainly developed in the physics literature.

  9. Quantum optics

    DEFF Research Database (Denmark)

    Andersen, Ulrik Lund

    2013-01-01

    Further sensitivity improvements are required before advanced optical interferometers will be able to measure gravitational waves. A team has now shown that introducing quantum squeezing of light may help to detect these elusive waves.......Further sensitivity improvements are required before advanced optical interferometers will be able to measure gravitational waves. A team has now shown that introducing quantum squeezing of light may help to detect these elusive waves....

  10. Quantum curves

    OpenAIRE

    Schwarz, Albert

    2014-01-01

    One says that a pair (P,Q) of ordinary differential operators specify a quantum curve if [P,Q]=const. If a pair of difference operators (K,L) obey the relation KL=const LK we say that they specify a discrete quantum curve. This terminology is prompted by well known results about commuting differential and difference operators, relating pairs of such operators with pairs of meromorphic functions on algebraic curves obeying some conditions. ...

  11. Quantum torsors

    OpenAIRE

    Grunspan, C.

    2002-01-01

    This text gives some results about quantum torsors. Our starting point is an old reformulation of torsors recalled recently by Kontsevich. We propose an unification of the definitions of torsors in algebraic geometry and in Poisson geometry. Any quantum torsor is equipped with two comodule-algebra structures over Hopf algebras and these structures commute with each other. In the finite dimensional case, these two Hopf algebras share the same finite dimension. We show that any Galois extension...

  12. Quantum lottery

    CERN Multimedia

    CERN Bulletin

    2013-01-01

    On April Fools' Day, CERN Quantum Diaries blogger Pauline Gagnon held a giveaway of microscopic proportion. Up for grabs? Ten Higgs bosons, courtesy of CERN. Pauline announced the winners last week; let's see what they'll really be getting in the mail...   Custom-made Particle Zoo Higgs bosons were sent out to the winners. Read more about the prize in the Quantum Diaries post "Higgs boson lottery: when CERN plays April Fools' jokes".

  13. Forecasting of Corrosion Properties of Steel Wires for Production of Guide Wires for Cardiological Treatment

    Directory of Open Access Journals (Sweden)

    J. Przondziono

    2013-01-01

    Full Text Available The study presents evaluation of the influence of strain in drawing process and of surface modification on resistance to electrochemical corrosion of wires made of stainless steel for production of guide wires used in invasive cardiology. The results of static tensile test enabled us to determine the course of flow curve of wires made of X10CrNi 18-8 steel as well as mathematical form of flow stress function. Resistance to electrochemical corrosion was evaluated on the ground of registered anodic polarisation curves by means of potentiodynamic method. The tests were performed in solution simulating human blood on samples that were electrolytically polished and samples that were polished and then chemically passivated. Exemplary anodic polarisation curves were given. It was proved that with the applied strain, corrosion properties decrease. It was found that chemical passivation improves wire corrosion characteristics. Statistical analysis showed that there is a significant dependence between corrosion properties (polarisation resistance Rp and strain ε applied in drawing process. Functions that present the change Rp=f(ε were selected. The issue is of importance to guide wire manufacturers because application of the suggested methodology will enable us to forecast corrosion characteristics of wire with the required strength drawn with the applied strain.

  14. Research regarding wires elastic deformations influence on joints positioning of a wire-driven robotic arm

    Science.gov (United States)

    Ciofu, C.; Stan, G.

    2016-08-01

    In this paper, we present the influence of driving wires deformation on positioning precision of joints from an elephant's trunk robotic arm. Robotic arms driven by wires have the joint accuracy largely depending on wires rigidity. The joint moment of resistance causes elastic deformation of wires and it is determined by: manipulated object load, weight loads previous to the analyzed joint and inherent resistance moment of joint. Static load analysis emphasizes the particular wires elastic deformation of each driven joint from an elephant's trunk robotic arm with five degrees of freedom. We consider the case of a constant manipulated load. Errors from each driving system of joints are not part of the closed loop system. Thus, precision positioning depends on wires elastic deformation which is about microns and causes angle deviation of joints about tens of minutes of sexagesimal degrees. The closer the joints to base arm the smaller positioning precision of joint. The obtained results are necessary for further compensation made by electronic corrections in the programming algorithm of the elephant's trunk robotic arm to improve accuracy.

  15. Quantum entanglement and quantum computational algorithms

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 56; Issue 2-3. Quantum entanglement ... Arvind. Quantum information processing Volume 56 Issue 2-3 February-March 2001 pp 357-365 ... The existence of entangled quantum states gives extra power to quantum computers over their classical counterparts. Quantum ...

  16. Quantum Computation and Quantum Spin Dynamics

    NARCIS (Netherlands)

    Raedt, Hans De; Michielsen, Kristel; Hams, Anthony; Miyashita, Seiji; Saito, Keiji

    2001-01-01

    We analyze the stability of quantum computations on physically realizable quantum computers by simulating quantum spin models representing quantum computer hardware. Examples of logically identical implementations of the controlled-NOT operation are used to demonstrate that the results of a quantum

  17. SPECIFIC FEATURES OF TECHNOLOGY OF MANUFACTURING A ZINC-COATED TUB WIRE FOR MUZZLE (BOTTLE’ HOOD WIRE

    Directory of Open Access Journals (Sweden)

    D. B. Zuev

    2016-01-01

    Full Text Available The paper presents the main technical specifications of galvanized low carbon wire for muzzles (bottle’hood wire, consistent with the exploitation requirements to the wire in the manufacture and use of muzzles. The main criteria when selecting the steel grade and upon selection of the technological processes are given. 

  18. Quantum computing: Quantum advantage deferred

    Science.gov (United States)

    Childs, Andrew M.

    2017-12-01

    A type of optics experiment called a boson sampler could be among the easiest routes to demonstrating the power of quantum computers. But recent work shows that super-classical boson sampling may be a long way off.

  19. Quantum Physics for Beginners.

    Science.gov (United States)

    Strand, J.

    1981-01-01

    Suggests a new approach for teaching secondary school quantum physics. Reviews traditional approaches and presents some characteristics of the three-part "Quantum Physics for Beginners" project, including: quantum physics, quantum mechanics, and a short historical survey. (SK)

  20. Quantum Transmemetic Intelligence

    Science.gov (United States)

    Piotrowski, Edward W.; Sładkowski, Jan

    The following sections are included: * Introduction * A Quantum Model of Free Will * Quantum Acquisition of Knowledge * Thinking as a Quantum Algorithm * Counterfactual Measurement as a Model of Intuition * Quantum Modification of Freud's Model of Consciousness * Conclusion * Acknowledgements * References

  1. Carbon wire chamber at sub-atmospheric pressure

    Science.gov (United States)

    Charles, G.; Audouin, L.; Bettane, J.; Dupre, R.; Genolini, B.; Hammoudi, N.; Imre, M.; Le Ven, V.; Maroni, A.; Mathon, B.; Nguyen Trung, T.; Rauly, E.

    2017-05-01

    Present in many experiments, wire and drift chambers have been used in a large variety of shapes and configurations during the last decades. Nevertheless, their readout elements has not evolved much: tungsten, sometimes gold-plated or aluminum, wires. By taking advantage of the developments in the manufacture of conducting carbon fiber, we could obtain interesting improvements for wire detectors. In this article, we present recent tests and simulations using carbon fibers to readout signal in place of traditional tungsten wires. Unlike metallic wires, their low weight guaranties a reduced quantity of material in the active area.

  2. A Laser Based Instrument for MWPC Wire Tension Measurement

    CERN Document Server

    Baldini, W; Evangelisti, F; Germani, S; Landi, L; Savrié, M; Graziani, G; Lenti, M; Lenzi, M; Passaleva, G; Carboni, G; De Capua, S; Kachtchouk, A

    2007-01-01

    A fast and simple method for the measurement of the mechanical tension of wires of Multi Wires Proportional Chambers (MWPCs) is described. The system is based on commercial components and does not require any electrical connection to the wires or electric or magnetic field. It has been developed for the quality control of MWPCs of the Muon Detector of the LHCb experiment in construction at CERN. The system allows a measurement of the wire tension with a precision better than 0.5% within 3-4 seconds per wire

  3. Model of Carbon Wire Heating in Accelerator Beam

    CERN Document Server

    Sapinski, M

    2008-01-01

    A heat flow equation with beam-induced heating and various cooling processes for a carbon wire passing through a particle beam is solved. Due to equation nonlinearity a numerical approach based on discretization of the wire movement is used. Heating of the wire due to the beam-induced electromagnetic field is taken into account. An estimation of the wire sublimation rate is made. The model is tested on SPS, LEP and Tevatron Main Injector data. Results are discussed and conclusions about limits of Wire Scanner operation on LHC beams are drawn.

  4. Laparoscopic extraction of fractured Kirschner wire from the pelvis

    Directory of Open Access Journals (Sweden)

    Vinaykumar N Thati

    2014-01-01

    Full Text Available Kirschner wire is a sharp stainless steel guide wire commonly used in fixation of fractured bone segments. There are case reports of migrated K wire from the upper limb into the spine and chest, and from the lower limb in to the abdomen and pelvis. Here, we present a case report of accidental intra-operative fracture of K wire during percutaneous femoral nailing for sub-trochanteric fracture of right femur, which migrated in to the pelvis when the orthopaedician tried to retrieve the broken segment of the K wire. This case highlights the use of laparoscopy as minimally invasive surgical option.

  5. PT quantum mechanics.

    Science.gov (United States)

    Bender, Carl M; DeKieviet, Maarten; Klevansky, S P

    2013-04-28

    PT-symmetric quantum mechanics (PTQM) has become a hot area of research and investigation. Since its beginnings in 1998, there have been over 1000 published papers and more than 15 international conferences entirely devoted to this research topic. Originally, PTQM was studied at a highly mathematical level and the techniques of complex variables, asymptotics, differential equations and perturbation theory were used to understand the subtleties associated with the analytic continuation of eigenvalue problems. However, as experiments on PT-symmetric physical systems have been performed, a simple and beautiful physical picture has emerged, and a PT-symmetric system can be understood as one that has a balanced loss and gain. Furthermore, the PT phase transition can now be understood intuitively without resorting to sophisticated mathematics. Research on PTQM is following two different paths: at a fundamental level, physicists are attempting to understand the underlying mathematical structure of these theories with the long-range objective of applying the techniques of PTQM to understanding some of the outstanding problems in physics today, such as the nature of the Higgs particle, the properties of dark matter, the matter-antimatter asymmetry in the universe, neutrino oscillations and the cosmological constant; at an applied level, new kinds of PT-synthetic materials are being developed, and the PT phase transition is being observed in many physical contexts, such as lasers, optical wave guides, microwave cavities, superconducting wires and electronic circuits. The purpose of this Theme Issue is to acquaint the reader with the latest developments in PTQM. The articles in this volume are written in the style of mini-reviews and address diverse areas of the emerging and exciting new area of PT-symmetric quantum mechanics.

  6. Quantum Phase Transitions in Quantum Dots

    OpenAIRE

    Rau, I. G.; Amasha, S.; Oreg, Y.; Goldhaber-Gordon, D.

    2013-01-01

    This review article describes theoretical and experimental advances in using quantum dots as a system for studying impurity quantum phase transitions and the non-Fermi liquid behavior at the quantum critical point.

  7. Quantum Communication and Quantum Multivariate Polynomial Interpolation

    Science.gov (United States)

    Diep, Do Ngoc; Giang, Do Hoang

    2017-09-01

    The paper is devoted to the problem of multivariate polynomial interpolation and its application to quantum secret sharing. We show that using quantum Fourier transform one can produce the protocol for quantum secret sharing distribution.

  8. Long distance quantum teleportation

    Science.gov (United States)

    Xia, Xiu-Xiu; Sun, Qi-Chao; Zhang, Qiang; Pan, Jian-Wei

    2018-01-01

    Quantum teleportation is a core protocol in quantum information science. Besides revealing the fascinating feature of quantum entanglement, quantum teleportation provides an ultimate way to distribute quantum state over extremely long distance, which is crucial for global quantum communication and future quantum networks. In this review, we focus on the long distance quantum teleportation experiments, especially those employing photonic qubits. From the viewpoint of real-world application, both the technical advantages and disadvantages of these experiments are discussed.

  9. Solar power wires based on organic photovoltaic materials.

    Science.gov (United States)

    Lee, Michael R; Eckert, Robert D; Forberich, Karen; Dennler, Gilles; Brabec, Christoph J; Gaudiana, Russell A

    2009-04-10

    Organic photovoltaics in a flexible wire format has potential advantages that are described in this paper. A wire format requires long-distance transport of current that can be achieved only with conventional metals, thus eliminating the use of transparent oxide semiconductors. A phase-separated, photovoltaic layer, comprising a conducting polymer and a fullerene derivative, is coated onto a thin metal wire. A second wire, coated with a silver film, serving as the counter electrode, is wrapped around the first wire. Both wires are encased in a transparent polymer cladding. Incident light is focused by the cladding onto to the photovoltaic layer even when it is completely shadowed by the counter electrode. Efficiency values of the wires range from 2.79% to 3.27%.

  10. Research on wire rope stress distribution of WR-CVT

    Science.gov (United States)

    Zhang, Wu; Guo, Wei; Zhang, Chuanwei; Lu, Zhengxiong; Xu, Xiaobin

    2017-10-01

    A wire rope continuously variable transmissions (WR-CVT) has been introduced in the paper, in view of its less research, this paper mainly studied the stress distribution of 6×7+IWS bending wire rope. The results shown that the wire stress is layered distribution in each section, the stress at the outer strand center wire and outer strand side wire was the greatest, the stress value of the outer strand side wire and metal block circular notch is second. As the transmission ratio decreases, the wire stress decreases, which is related to the pulley working radius increases. Compared with the section A1, the stress value on the section A2 is smaller, mainly because the section A2 is not in contact with the metal block or the contact pressure is small. This study provides a basis for the study of fatigue and wears failure of WR-CVT components.

  11. Coherently wired light-harvesting in photosynthetic marine algae at ambient temperature.

    Science.gov (United States)

    Collini, Elisabetta; Wong, Cathy Y; Wilk, Krystyna E; Curmi, Paul M G; Brumer, Paul; Scholes, Gregory D

    2010-02-04

    Photosynthesis makes use of sunlight to convert carbon dioxide into useful biomass and is vital for life on Earth. Crucial components for the photosynthetic process are antenna proteins, which absorb light and transmit the resultant excitation energy between molecules to a reaction centre. The efficiency of these electronic energy transfers has inspired much work on antenna proteins isolated from photosynthetic organisms to uncover the basic mechanisms at play. Intriguingly, recent work has documented that light-absorbing molecules in some photosynthetic proteins capture and transfer energy according to quantum-mechanical probability laws instead of classical laws at temperatures up to 180 K. This contrasts with the long-held view that long-range quantum coherence between molecules cannot be sustained in complex biological systems, even at low temperatures. Here we present two-dimensional photon echo spectroscopy measurements on two evolutionarily related light-harvesting proteins isolated from marine cryptophyte algae, which reveal exceptionally long-lasting excitation oscillations with distinct correlations and anti-correlations even at ambient temperature. These observations provide compelling evidence for quantum-coherent sharing of electronic excitation across the 5-nm-wide proteins under biologically relevant conditions, suggesting that distant molecules within the photosynthetic proteins are 'wired' together by quantum coherence for more efficient light-harvesting in cryptophyte marine algae.

  12. Thin Magnetically Soft Wires for Magnetic Microsensors

    Directory of Open Access Journals (Sweden)

    Arcady Zhukov

    2009-11-01

    Full Text Available Recent advances in technology involving magnetic materials require development of novel advanced magnetic materials with improved magnetic and magneto-transport properties and with reduced dimensionality. Therefore magnetic materials with outstanding magnetic characteristics and reduced dimensionality have recently gained much attention. Among these magnetic materials a family of thin wires with reduced geometrical dimensions (of order of 1–30 μm in diameter have gained importance within the last few years. These thin wires combine excellent soft magnetic properties (with coercivities up to 4 A/m with attractive magneto-transport properties (Giant Magneto-impedance effect, GMI, Giant Magneto-resistance effect, GMR and an unusual re-magnetization process in positive magnetostriction compositions exhibiting quite fast domain wall propagation. In this paper we overview the magnetic and magneto-transport properties of these microwires that make them suitable for microsensor applications.

  13. Superconducting wire turns to electrical power

    CERN Document Server

    Sargent, P

    2003-01-01

    Two years after the discovery that magnesium diboride is a superconductor, engineers and entrepreneurs are keen to transform its properties into profit. The discovery of superconductivity at 39 K in the metallic compound magnesium diboride two years ago created quite a stir. Since then, physicists and chemists have come a long way in understanding the curious set of circumstances that lead to such a high critical temperature in this widely available material. At the same time, metallurgists, engineers and entrepreneurs have been focusing on the commercial potential of magnesium diboride as superconducting wire, which was the subject of a one-day meeting in Cambridge, UK, in April. Superconducting wire made from magnesium diboride could make 'second- generation' electrical machines commercially viable. (U.K.)

  14. Polynomial description of inhomogeneous topological superconducting wires

    Science.gov (United States)

    Pérez, Marcos; Martínez, Gerardo

    2017-11-01

    We present the universal features of the topological invariant for p-wave superconducting wires after the inclusion of spatial inhomogeneities. Three classes of distributed potentials are studied, a single-defect, a commensurate and an incommensurate model, using periodic site modulations. An analytic polynomial description is achieved by splitting the topological invariant into two parts; one part depends on the chemical potential and the other does not. For the homogeneous case, an elliptical region is found where the topological invariant oscillates. The zeros of these oscillations occur at points where the fermion parity switches for finite wires. The increase of these oscillations with the inhomogeneity strength leads to new isolated non-topological phases. We characterize these new phases according to each class of spatial distributions. Such phases could also be observed in the XY model, to which our model is dual.

  15. Capacitance Control on the Wire Production Line

    Directory of Open Access Journals (Sweden)

    Goldshtein Alexander

    2016-01-01

    Full Text Available The paper presents technical implementation of the electricalcapacitive method to perform in-process measurement of the capacitance per unit length of a single-core electric wire. The design of the electrocapacitive measuring transducer is proposed. The block diagram of the device CAP-10 developed to implement the proposed method is presented. The appearance of the device CAP-10 is showed, and its operating principle is described. It is shown that the change in water conductivity has a significant impact of the measurement result of the wire capacitance per unit length. The techniques to offset from the impact of water conductivity variation on measurement results are proposed. The technique of the device CAP-10 initial adjustment is proposed. It provides the desired function of the output signal transformation. The technique of the ‘operating’ adjustment to correct measurement results through systematic measurement error elimination is offered.

  16. Aging analyses of aircraft wire insulation

    Energy Technology Data Exchange (ETDEWEB)

    GILLEN,KENNETH T.; CLOUGH,ROGER LEE; CELINA,MATHIAS C.; AUBERT,JAMES H.; MALONE,G. MICHAEL

    2000-05-08

    Over the past two decades, Sandia has developed a variety of specialized analytical techniques for evaluating the long-term aging and stability of cable insulation and other related materials. These techniques have been applied to cable reliability studies involving numerous insulation types and environmental factors. This work has allowed the monitoring of the occurrence and progression of cable material deterioration in application environments, and has provided insights into material degradation mechanisms. It has also allowed development of more reliable lifetime prediction methodologies. As a part of the FAA program for intrusive inspection of aircraft wiring, they are beginning to apply a battery of techniques to assessing the condition of cable specimens removed from retired aircraft. It is anticipated that in a future part of this program, they may employ these techniques in conjunction with accelerated aging methodologies and models that the authros have developed and employed in the past to predict cable lifetimes. The types of materials to be assessed include 5 different wire types: polyimide, PVC/Glass/Nylon, extruded XL-polyalkene/PVDF, Poly-X, and XL-ETFE. This presentation provides a brief overview of the main techniques that will be employed in assessing the state of health of aircraft wire insulation. The discussion will be illustrated with data from their prior cable aging studies, highlighting the methods used and their important conclusions. A few of the techniques that they employ are widely used in aging studies on polymers, but others are unique to Sandia. All of their techniques are non-proprietary, and maybe of interest for use by others in terms of application to aircraft wiring analysis. At the end of this report is a list showing some leading references to papers that have been published in the open literature which provide more detailed information on the analytical techniques for elastomer aging studies. The first step in the

  17. Heat Transfer Analysis in Wire Bundles for Aerospace Vehicles

    Science.gov (United States)

    Rickman, S. L.; Iamello, C. J.

    2016-01-01

    Design of wiring for aerospace vehicles relies on an understanding of "ampacity" which refers to the current carrying capacity of wires, either, individually or in wire bundles. Designers rely on standards to derate allowable current flow to prevent exceedance of wire temperature limits due to resistive heat dissipation within the wires or wire bundles. These standards often add considerable margin and are based on empirical data. Commercial providers are taking an aggressive approach to wire sizing which challenges the conventional wisdom of the established standards. Thermal modelling of wire bundles may offer significant mass reduction in a system if the technique can be generalized to produce reliable temperature predictions for arbitrary bundle configurations. Thermal analysis has been applied to the problem of wire bundles wherein any or all of the wires within the bundle may carry current. Wire bundles present analytical challenges because the heat transfer path from conductors internal to the bundle is tortuous, relying on internal radiation and thermal interface conductance to move the heat from within the bundle to the external jacket where it can be carried away by convective and radiative heat transfer. The problem is further complicated by the dependence of wire electrical resistivity on temperature. Reduced heat transfer out of the bundle leads to higher conductor temperatures and, hence, increased resistive heat dissipation. Development of a generalized wire bundle thermal model is presented and compared with test data. The steady state heat balance for a single wire is derived and extended to the bundle configuration. The generalized model includes the effects of temperature varying resistance, internal radiation and thermal interface conductance, external radiation and temperature varying convective relief from the free surface. The sensitivity of the response to uncertainties in key model parameters is explored using Monte Carlo analysis.

  18. Wire chambers with their magnetostrictive readout

    CERN Multimedia

    1974-01-01

    This set of wire chamber planes shaped as a cylinder sector was installed inside the magnet of a polarized spin target modified to allow as well momentum analysis of the produced particles. The experiment (S126) was set up by the CERN-Trieste Collaboration in the PS beam m9 to measure spin effects in the associated production of of a positive kaon and a positive Sigma by interaction of a positive pion with polarized protons.

  19. Waste steel wires modified structural lightweight concrete

    OpenAIRE

    Aghaee, Kamran; Yazdi,Mohammad Ali

    2014-01-01

    Nowadays, the use of different waste fibers in concrete has started to increase rapidly due to some reasons such as economic savings and positive effects on the environment. In this study, waste steel wires taken from reinforcement and formwork which were previously utilized in construction projects, were employed in structural lightweight concrete (SLWC). The objective was to investigate the possibility of using this type of fiber as reinforcement in the SLWC. Compressive, tensile, flexural ...

  20. Buoyant Helical Twin-Axial Wire Antenna

    Science.gov (United States)

    2016-11-15

    Wire Antenna” by the inventor, David A. Tonn. STATEMENT OF GOVERNMENT INTEREST [0002] The invention described herein may be manufactured and used by...BACKGROUND OF THE INVENTION (1) Field of the Invention [0003] The present invention is directed to a linear antenna for dual frequencies and a method for...curves and hinders the submarine’s operations when using the antenna. SUMMARY OF THE INVENTION [0006] It is a first object of the present

  1. NA48: Wiring up for Change

    CERN Multimedia

    2001-01-01

    The NA48 Collaboration is rebuilding its drift chambers ready for the experiment to start up again this coming July. An intricate task involving the soldering of over 24,000 wires! The future of the NA48 experiment is coming right down to the wire, that is, the wires which the Collaboration is installing in the clean room of Hall 887 on the Prévessin site. Six days a week, technicians are working in shifts to rebuild the experiment's drift chambers. The original chambers were damaged when a section of a vacuum tube imploded at the end of 1999. A year ago, CERN gave the green light for this essential part of the spectrometer to be rebuilt, so the NA48 experiment, which studies CP violation (see box), still has a bright future ahead of it. Three years of data-taking ahead The NA48 experiment aims to penetrate the secrets of CP (Charge Parity) violation. Charge and parity are two parameters which distinguish a particle from an antiparticle. In other words, an electron possesses a negative electric ...

  2. Laser welding of NiTi wires

    Energy Technology Data Exchange (ETDEWEB)

    Gugel, H. [Institute for Materials, Materials Technology, Ruhr-University Bochum, Bochum (Germany)], E-mail: hajo.gugel@rub.de; Schuermann, A.; Theisen, W. [Institute for Materials, Materials Technology, Ruhr-University Bochum, Bochum (Germany)

    2008-05-25

    The special properties of nickel-titanium shape memory alloys are currently used in micro-engineering and medical technology. In order to integrate NiTi components into existing parts and modules, they often need to be joined to other materials. For this reason, the present contribution deals with the laser welding of thin pseudoelastic NiTi wires (100 {mu}m) with an Nd:YAG laser. Based on extensive parameter studies, faultless joints were produced. This study deals with the structural changes occurring in the fusion and heat-affected zones, the performance of the joints in static tensile tests and their functional fatigue. It can be shown that NiTi/NiTi joints reach about 75% of the ultimate tensile strength of pure NiTi wires. For welding NiTi to steel, no interlayer was used. The dissimilar NiTi/steel joints provide a bonding strength in the fusion and heat-affected zones higher than the plateau stress level. NiTi/steel joints of thin wires, as a new aspect, enable the possibility to benefit from the pseudoelastic properties of the NiTi component.

  3. Quantum mechanics

    CERN Document Server

    Ghosh, P K

    2014-01-01

    Quantum mechanics, designed for advanced undergraduate and graduate students of physics, mathematics and chemistry, provides a concise yet self-contained introduction to the formal framework of quantum mechanics, its application to physical problems and the interpretation of the theory. Starting with a review of some of the necessary mathematics, the basic concepts are carefully developed in the text. After building a general formalism, detailed treatment of the standard material - the harmonic oscillator, the hydrogen atom, angular momentum theory, symmetry transformations, approximation methods, identical particle and many-particle systems, and scattering theory - is presented. The concluding chapter discusses the interpretation of quantum mechanics. Some of the important topics discussed in the book are the rigged Hilbert space, deformation quantization, path integrals, coherent states, geometric phases, decoherene, etc. This book is characterized by clarity and coherence of presentation.

  4. Quantum deconvolution

    Science.gov (United States)

    Bény, Cédric

    2018-02-01

    We propose a method for stably removing noise from measurements of a quantum many-body system. The question is cast to a linear inverse problem by using a quantum Fischer information metric as figure of merit. This requires the ability to compute the adjoint of the noise channel with respect to the metric, which can be done analytically when the metric is evaluated at a Gaussian (quasi-free) state. This approach can be applied effectively to n-point functions of a quantum field theory. For translation invariant noise, this yields a stable deconvolution method on the first moments of the field which differs from what one would obtain from a purely classical analysis.

  5. Quantum waveguides

    CERN Document Server

    Exner, Pavel

    2015-01-01

    This monograph explains the theory of quantum waveguides, that is, dynamics of quantum particles confined to regions in the form of tubes, layers, networks, etc. The focus is on relations between the confinement geometry on the one hand and the spectral and scattering properties of the corresponding quantum Hamiltonians on the other. Perturbations of such operators, in particular, by external fields are also considered. The volume provides a unique summary of twenty five years of research activity in this area and indicates ways in which the theory can develop further. The book is fairly self-contained. While it requires some broader mathematical physics background, all the basic concepts are properly explained and proofs of most theorems are given in detail, so there is no need for additional sources. Without a parallel in the literature, the monograph by Exner and Kovarik guides the reader through this new and exciting field.

  6. Quantum weirdness

    CERN Document Server

    Mullin, William J

    2017-01-01

    Quantum mechanics allows a remarkably accurate description of nature and powerful predictive capabilities. The analyses of quantum systems and their interpretation lead to many surprises, for example, the ability to detect the characteristics of an object without ever touching it in any way, via "interaction-free measurement," or the teleportation of an atomic state over large distances. The results can become downright bizarre. Quantum mechanics is a subtle subject that usually involves complicated mathematics -- calculus, partial differential equations, etc., for complete understanding. Most texts for general audiences avoid all mathematics. The result is that the reader misses almost all deep understanding of the subject, much of which can be probed with just high-school level algebra and trigonometry. Thus, readers with that level of mathematics can learn so much more about this fundamental science. The book starts with a discussion of the basic physics of waves (an appendix reviews some necessary class...

  7. Blind Quantum Signature with Blind Quantum Computation

    Science.gov (United States)

    Li, Wei; Shi, Ronghua; Guo, Ying

    2017-04-01

    Blind quantum computation allows a client without quantum abilities to interact with a quantum server to perform a unconditional secure computing protocol, while protecting client's privacy. Motivated by confidentiality of blind quantum computation, a blind quantum signature scheme is designed with laconic structure. Different from the traditional signature schemes, the signing and verifying operations are performed through measurement-based quantum computation. Inputs of blind quantum computation are securely controlled with multi-qubit entangled states. The unique signature of the transmitted message is generated by the signer without leaking information in imperfect channels. Whereas, the receiver can verify the validity of the signature using the quantum matching algorithm. The security is guaranteed by entanglement of quantum system for blind quantum computation. It provides a potential practical application for e-commerce in the cloud computing and first-generation quantum computation.

  8. Quantum mechanics

    CERN Document Server

    Rae, Alastair I M

    2007-01-01

    PREFACESINTRODUCTION The Photoelectric Effect The Compton Effect Line Spectra and Atomic Structure De Broglie Waves Wave-Particle Duality The Rest of This Book THE ONE-DIMENSIONAL SCHRÖDINGER EQUATIONS The Time-Dependent Schrödinger Equation The Time-Independent Schrödinger Equation Boundary ConditionsThe Infinite Square Well The Finite Square Well Quantum Mechanical Tunneling The Harmonic Oscillator THE THREE-DIMENSIONAL SCHRÖDINGER EQUATIONS The Wave Equations Separation in Cartesian Coordinates Separation in Spherical Polar Coordinates The Hydrogenic Atom THE BASIC POSTULATES OF QUANTUM MEC

  9. Quantum Graphology

    Science.gov (United States)

    Kottos, T.

    2007-01-01

    We review quantum chaos on graphs. We construct a unitary operator which represents the quantum evolution on the graph and study its spectral and wave function statistics. This operator is the analogue of the classical evolution operator on the graph. It allows us to establish a connection between the corresponding periodic orbits and the statistical properties of eigenvalues and eigenfunctions. Specifically, for the energy-averaged spectral form factor we derived an exact combinatorial expression which illustrate the role of correlations between families of isometric orbits. We also show that enhanced wave function localization due to the presence of short unstable periodic orbits and strong scarring can rely on completely different mechanisms

  10. Quantum Cosmology

    OpenAIRE

    Bojowald, Martin

    2006-01-01

    A complete model of the universe needs at least three parts: (1) a complete set of physical variables and dynamical laws for them, (2) the correct solution of the dynamical laws, and (3) the connection with conscious experience. In quantum cosmology, item (2) is the quantum state of the cosmos. Hartle and Hawking have made the `no-boundary' proposal, that the wavefunction of the universe is given by a path integral over all compact Euclidean 4-dimensional geometries and matter fields that hav...

  11. Quantum protocols

    OpenAIRE

    Buhrman, Harry

    2006-01-01

    École thématique; Quantum Information, Computation and Complexity * Programme at the Institut Henri Poincaré, January 4th – April 7th, 2006 * Organizers: Ph.Grangier, M.Santha and D.L.Shepelyansky * Lectures have been filmed by Peter Rapcan and Michal Sedlak from Bratislava with the support of the Marie Curie RTN "CONQUEST" A trimester at the Centre Emile Borel - Institut Henri Poincaré is devoted to modern developments in a rapidly growing field of quantum information and communication, quan...

  12. Quantum mechanics

    CERN Document Server

    Zagoskin, Alexandre

    2015-01-01

    Written by Dr Alexandre Zagoskin, who is a Reader at Loughborough University, Quantum Mechanics: A Complete Introduction is designed to give you everything you need to succeed, all in one place. It covers the key areas that students are expected to be confident in, outlining the basics in clear jargon-free English, and then providing added-value features like summaries of key ideas, and even lists of questions you might be asked in your exam. The book uses a structure that is designed to make quantum physics as accessible as possible - by starting with its similarities to Newtonian physics, ra

  13. Experimental and numeric study of aluminum wire explosion in vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Tkachenko, S.I.; Khattatov, T.A.; Tilikin, I.N. [MIPT, Dolgoprudny, Moscow Region (Russian Federation); Romanova, V.M.; Mingaleev, A.R.; Ter-Oganesyan, A.E.; Shelkovenko, T.A.; Pikuz, S.A. [P.N. Lebedev Physical Institute RAS, Moscow (Russian Federation); Olhovskaya, O.G.; Krukovskij, A.Y.; Gasilov, V.A.; Novikov, V.G. [IMM RAS, Moscow (Russian Federation)

    2011-07-01

    Full text of publication follows: Distribution of matter in the discharge channel formed upon a nanosecond electrical explosion of Al wire in vacuum was studied experimentally and theoretically. Several series of experiments with 25 {mu}m diameter 12 mm long wires were performed; the charging voltage, the current amplitude and current rise rate were U{sub 0} = 20 kV, Imax {approx} 10 kA and dI/dt = 50 A/ns, respectively [1]. 'Shadow and Schlieren' images of the discharge channel were obtained using optical probing at the second harmonic of a YAG: Nd{sup +3} laser ({lambda} = 0.532 {mu}m, {tau} {approx} 70 ps). Simultaneous use of optical and UV diagnostics made it possible to distinguish qualitatively different regions of the discharge channel, such as the current-carrying plasma layers and the region occupied by a weakly conducting cold matter. The simulations were performed using a program containing the Braginsky two temperature magnetic gas-dynamic model: Lagrange-Euler code RAZRYAD-2.5 [2] on the basis of homogeneous, conservative and implicit differences of MHD schemes. Radiation energy exchange is accounted for in a multi-group (from the spectrum) approximation, using a radiation diffusion model. Heat- and electro- conductivity anisotropy in magnetic field is taken into account. Tables of thermal-physical and optical properties of aluminum were used in calculations in the present work [3]. The influence of radiation on the distribution of the parameters of matter (temperature, density) and current density in the discharge channel was studied. Several variants with differing amounts of radiation of spectral groups were evaluated. The obtained results are compared with experimental data. This work was supported in part by the RFBR 08-08-00688, 09-02-01532, and the ESC FIAN.; [1]. S.I. Tkachenko et. al., Plasma Physics Reports, 2009, Vol. 35, No. 9, pp. 734-753; [2]. V.A. Gasilov et. al., Mathematical Modelling, 2003, v. 15, No 9, pp. 107-124; [3]. A

  14. Body of Knowledge (BOK) for Copper Wire Bonds

    Science.gov (United States)

    Rutkowski, E.; Sampson, M. J.

    2015-01-01

    Copper wire bonds have replaced gold wire bonds in the majority of commercial semiconductor devices for the latest technology nodes. Although economics has been the driving mechanism to lower semiconductor packaging costs for a savings of about 20% by replacing gold wire bonds with copper, copper also has materials property advantages over gold. When compared to gold, copper has approximately: 25% lower electrical resistivity, 30% higher thermal conductivity, 75% higher tensile strength and 45% higher modulus of elasticity. Copper wire bonds on aluminum bond pads are also more mechanically robust over time and elevated temperature due to the slower intermetallic formation rate - approximately 1/100th that of the gold to aluminum intermetallic formation rate. However, there are significant tradeoffs with copper wire bonding - copper has twice the hardness of gold which results in a narrower bonding manufacturing process window and requires that the semiconductor companies design more mechanically rigid bonding pads to prevent cratering to both the bond pad and underlying chip structure. Furthermore, copper is significantly more prone to corrosion issues. The semiconductor packaging industry has responded to this corrosion concern by creating a palladium coated copper bonding wire, which is more corrosion resistant than pure copper bonding wire. Also, the selection of the device molding compound is critical because use of environmentally friendly green compounds can result in internal CTE (Coefficient of Thermal Expansion) mismatches with the copper wire bonds that can eventually lead to device failures during thermal cycling. Despite the difficult problems associated with the changeover to copper bonding wire, there are billions of copper wire bonded devices delivered annually to customers. It is noteworthy that Texas Instruments announced in October of 2014 that they are shipping microcircuits containing copper wire bonds for safety critical automotive applications

  15. Kirschner Wire Fixation for the Treatment of Comminuted Zygomatic Fractures

    Science.gov (United States)

    Kang, Dai-Hun; Jung, Dong-Woo; Kim, Yong-Ha; Kim, Tae-Gon; Lee, JunHo

    2015-01-01

    Background The Kirschner wire (K-wire) technique allows stable fixation of bone fragments without periosteal dissection, which often lead to bone segment scattering and loss. The authors used the K-wire fixation to simplify the treatment of laborious comminuted zygomatic bone fracture and report outcomes following the operation. Methods A single-institution retrospective review was performed for all patients with comminuted zygomatic bone fractures between January 2010 and December 2013. In each patient, the zygoma was reduced and fixed with K-wire, which was drilled from the cheek bone and into the contralateral nasal cavity. For severely displaced fractures, the zygomaticofrontal suture was first fixated with a microplate and the K-wire was used to increase the stability of fixation. Each wire was removed approximately 4 weeks after surgery. Surgical outcomes were evaluated for malar eminence, cheek symmetry, Kwire site scar, and complications (based on a 4-point scale from 0 to 3, where 0 point is 'poor' and 3 points is 'excellent'). Results The review identified 25 patients meeting inclusion criteria (21 men and 4 women). The mean age was 52 years (range, 15-73 years). The mean follow up duration was 6.2 months. The mean operation time was 21 minutes for K-wire alone (n=7) and 52 minutes for K-wire and plate fixation (n=18). Patients who had received K-wire only fixation had severe underlying diseases or accompanying injuries. The mean postoperative evaluation scores were 2.8 for malar contour and 2.7 for K-wire site scars. The mean patient satisfaction was 2.7. There was one case of inflammation due to the K-wire. Conclusion The use of K-wire technique was associated with high patient satisfaction in our review. K-wire fixation technique is useful in patient who require reduction of zygomatic bone fractures in a short operating time. PMID:28913236

  16. Quantum gravity and quantum cosmology

    CERN Document Server

    Papantonopoulos, Lefteris; Siopsis, George; Tsamis, Nikos

    2013-01-01

    Quantum gravity has developed into a fast-growing subject in physics and it is expected that probing the high-energy and high-curvature regimes of gravitating systems will shed some light on how to eventually achieve an ultraviolet complete quantum theory of gravity. Such a theory would provide the much needed information about fundamental problems of classical gravity, such as the initial big-bang singularity, the cosmological constant problem, Planck scale physics and the early-time inflationary evolution of our Universe.   While in the first part of this book concepts of quantum gravity are introduced and approached from different angles, the second part discusses these theories in connection with cosmological models and observations, thereby exploring which types of signatures of modern and mathematically rigorous frameworks can be detected by experiments. The third and final part briefly reviews the observational status of dark matter and dark energy, and introduces alternative cosmological models.   ...

  17. Quantum-dot-in-perovskite solids

    KAUST Repository

    Ning, Zhijun

    2015-07-15

    © 2015 Macmillan Publishers Limited. All rights reserved. Heteroepitaxy - atomically aligned growth of a crystalline film atop a different crystalline substrate - is the basis of electrically driven lasers, multijunction solar cells, and blue-light-emitting diodes. Crystalline coherence is preserved even when atomic identity is modulated, a fact that is the critical enabler of quantum wells, wires, and dots. The interfacial quality achieved as a result of heteroepitaxial growth allows new combinations of materials with complementary properties, which enables the design and realization of functionalities that are not available in the single-phase constituents. Here we show that organohalide perovskites and preformed colloidal quantum dots, combined in the solution phase, produce epitaxially aligned \\'dots-in-a-matrix\\' crystals. Using transmission electron microscopy and electron diffraction, we reveal heterocrystals as large as about 60 nanometres and containing at least 20 mutually aligned dots that inherit the crystalline orientation of the perovskite matrix. The heterocrystals exhibit remarkable optoelectronic properties that are traceable to their atom-scale crystalline coherence: photoelectrons and holes generated in the larger-bandgap perovskites are transferred with 80% efficiency to become excitons in the quantum dot nanocrystals, which exploit the excellent photocarrier diffusion of perovskites to produce bright-light emission from infrared-bandgap quantum-tuned materials. By combining the electrical transport properties of the perovskite matrix with the high radiative efficiency of the quantum dots, we engineer a new platform to advance solution-processed infrared optoelectronics.

  18. Quantum biological information theory

    CERN Document Server

    Djordjevic, Ivan B

    2016-01-01

    This book is a self-contained, tutorial-based introduction to quantum information theory and quantum biology. It serves as a single-source reference to the topic for researchers in bioengineering, communications engineering, electrical engineering, applied mathematics, biology, computer science, and physics. The book provides all the essential principles of the quantum biological information theory required to describe the quantum information transfer from DNA to proteins, the sources of genetic noise and genetic errors as well as their effects. Integrates quantum information and quantum biology concepts; Assumes only knowledge of basic concepts of vector algebra at undergraduate level; Provides a thorough introduction to basic concepts of quantum information processing, quantum information theory, and quantum biology; Includes in-depth discussion of the quantum biological channel modelling, quantum biological channel capacity calculation, quantum models of aging, quantum models of evolution, quantum models o...

  19. Quantum Computers

    Science.gov (United States)

    2010-03-04

    be required. In 2001, a breakthrough known as the KLM (Knill–Laflamme– Milburn13) scheme showed that scalable quantum computing is possible using only...and single-photon detection to induce interactions nondeterministically. In the past five years, the KLM scheme has moved from a mathematical proof

  20. Quantum Theory

    NARCIS (Netherlands)

    Raedt, Hans De; Binder, K; Ciccotti, G

    1996-01-01

    The purpose of this set of lectures is to introduce the general concepts that are at the basis of the computer simulation algorithms that are used to study the behavior of condensed matter quantum systems. The emphasis is on the underlying concepts rather than on specific applications. Topics

  1. Quantum dice

    Energy Technology Data Exchange (ETDEWEB)

    Sassoli de Bianchi, Massimiliano, E-mail: autoricerca@gmail.com

    2013-09-15

    In a letter to Born, Einstein wrote [42]: “Quantum mechanics is certainly imposing. But an inner voice tells me that it is not yet the real thing. The theory says a lot, but does not really bring us any closer to the secret of the ‘old one.’ I, at any rate, am convinced that He does not throw dice.” In this paper we take seriously Einstein’s famous metaphor, and show that we can gain considerable insight into quantum mechanics by doing something as simple as rolling dice. More precisely, we show how to perform measurements on a single die, to create typical quantum interference effects, and how to connect (entangle) two identical dice, to maximally violate Bell’s inequality. -- Highlights: •Rolling a die is a quantum process admitting a Hilbert space representation. •Rolling experiments with a single die can produce interference effects. •Two connected dice can violate Bell’s inequality. •Correlations need to be created by the measurement, to violate Bell’s inequality.

  2. Quantum Metaphotonics

    Science.gov (United States)

    2016-03-24

    semiconductors. Personnel Graduate students supported by this grant: Michael Gehl (Graduated with PhD in October 2015, now at Sandia... Ell , O. B. Shchekin, and D. G. Deppe, “Vacuum Rabi splitting with a single quantum dot in a photonic crystal nanocavity.” Nature 432, 200-203 (2004

  3. Quantum Biology

    Directory of Open Access Journals (Sweden)

    Alessandro Sergi

    2009-06-01

    Full Text Available A critical assessment of the recent developmentsof molecular biology is presented.The thesis that they do not lead to a conceptualunderstanding of life and biological systems is defended.Maturana and Varela's concept of autopoiesis is briefly sketchedand its logical circularity avoided by postulatingthe existence of underlying living processes,entailing amplification from the microscopic to the macroscopic scale,with increasing complexity in the passage from one scale to the other.Following such a line of thought, the currently accepted model of condensed matter, which is based on electrostatics and short-ranged forces,is criticized. It is suggested that the correct interpretationof quantum dispersion forces (van der Waals, hydrogen bonding, and so onas quantum coherence effects hints at the necessity of includinglong-ranged forces (or mechanisms for them incondensed matter theories of biological processes.Some quantum effects in biology are reviewedand quantum mechanics is acknowledged as conceptually important to biology since withoutit most (if not all of the biological structuresand signalling processes would not even exist. Moreover, it is suggested that long-rangequantum coherent dynamics, including electron polarization,may be invoked to explain signal amplificationprocess in biological systems in general.

  4. Quantum Computing

    Indian Academy of Sciences (India)

    start-up company at liT. Mumbai. Part 1. Building Blocks of Quan- tum Computers, Resonance, ..... by modeling the errors caused by decoherence. The interaction of a quantum system with the environment obstructs the unitary evolution of the system and causes dissipation of information, reducing coherence of information.

  5. Quantum cryptography beyond quantum key distribution

    NARCIS (Netherlands)

    Broadbent, A.; Schaffner, C.

    2016-01-01

    Quantum cryptography is the art and science of exploiting quantum mechanical effects in order to perform cryptographic tasks. While the most well-known example of this discipline is quantum key distribution (QKD), there exist many other applications such as quantum money, randomness generation,

  6. Quantum cryptography beyond quantum key distribution

    NARCIS (Netherlands)

    A. Broadbent (Anne); C. Schaffner (Christian)

    2016-01-01

    textabstractQuantum cryptography is the art and science of exploiting quantum mechanical effects in order to perform cryptographic tasks. While the most well-known example of this discipline is quantum key distribution (QKD), there exist many other applications such as quantum money, randomness

  7. Milestones toward Majorana-based quantum computing (Conference Presentation)

    Science.gov (United States)

    Mishmash, Ryan V.; Aasen, David; Hell, Michael; Higginbotham, Andrew; Danon, Jeroen; Leijnse, Martin; Jespersen, Thomas S.; Folk, Joshua A.; Marcus, Charles M.; Flensberg, Karsten; Alicea, Jason

    2016-10-01

    We introduce a scheme for preparation, manipulation, and readout of Majorana zero modes in semiconducting wires with mesoscopic superconducting islands. Our approach synthesizes recent advances in materials growth with tools commonly used in quantum-dot experiments, including gate-control of tunnel barriers and Coulomb effects, charge sensing, and charge pumping. We outline a sequence of milestones interpolating between zero-mode detection and quantum computing that includes (1) detection of fusion rules for non-Abelian anyons using either proximal charge sensors or pumped current; (2) validation of a prototype topological qubit; and (3) demonstration of non-Abelian statistics by braiding in a branched geometry. The first two milestones require only a single wire with two islands, and additionally enable sensitive measurements of the system's excitation gap, quasiparticle poisoning rates, residual Majorana zero-mode splittings, and topological-qubit coherence times. These pre-braiding experiments can be adapted to other manipulation and readout schemes as well.

  8. Efficient quantum walk on a quantum processor

    Science.gov (United States)

    Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L.; Wang, Jingbo B.; Matthews, Jonathan C. F.

    2016-01-01

    The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise, quantum walks have shown much potential as a framework for developing new quantum algorithms. Here we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor. PMID:27146471

  9. Efficient quantum walk on a quantum processor.

    Science.gov (United States)

    Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L; Wang, Jingbo B; Matthews, Jonathan C F

    2016-05-05

    The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise, quantum walks have shown much potential as a framework for developing new quantum algorithms. Here we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor.

  10. Exploring the Quantum Speed Limit with Computer Games

    DEFF Research Database (Denmark)

    Sørensen, Jens Jakob Winther Hedemann; Pedersen, Mads Kock; Munch, Michael Kulmback

    2016-01-01

    Humans routinely solve problems of immense computational complexity by intuitively forming simple, low-dimensional heuristic strategies. Citizen science exploits this intuition by presenting scientific research problems to non-experts. Gamification is an effective tool for attracting citizen...... scientists and allowing them to provide novel solutions to the research problems. Citizen science games have been used successfully in Foldit, EteRNA and EyeWire to study protein and RNA folding and neuron mapping. However, gamification has never been applied in quantum physics. Everyday experiences of non......-experts are based on classical physics and it is \\textit{a priori} not clear that they should have an intuition for quantum dynamics. Does this premise hinder the use of citizen scientists in the realm of quantum mechanics? Here we report on Quantum Moves, an online platform gamifying optimization problems...

  11. Atomically precise, coupled quantum dots fabricated by cleaved edge overgrowth

    Science.gov (United States)

    Wegscheider, W.; Schedelbeck, G.; Bichler, M.; Abstreiter, G.

    Recent progress in the fabrication of quantum dots by molecular beam epitaxy along three directions in space is reviewed. The optical properties of different sample structures consisting of individual quantum dots, pairs of coupled dots as well as of linear arrays of dots are studied by microscopic photoluminescence spectroscopy. The high degree of control over shape, composition and position of the 7×7×7 nm3 size GaAs quantum dots, which form at the intesection of three orthogonal quantum wells, allows a detailed investigation of the influence of coupling between almost identical zero-dimensional objects. In contrast to the inhomogeneously broadened quantum well and quantum wire signals originating from the complex twofold cleaved edge overgrowth structure, the photoluminescence spetrum of an individual quantum dot exhibits a single sharp line (full width at half maximum denomination "artificial atoms" for the quantum dots. It is further demonstrated that an "artifical molecule", characterized by the existence of bonding and antibonding states can be assembled from two of such "artificial atoms". The coupling strength between the "artificial atoms" is adjusted by the "interatomic" distance and is reflected in the energetic separation of the bonding and antibonding levels and the linewidths of the corresponding interband transitions.

  12. COMPARISON OF WIRELESS NETWORK OVER WIRED NETWORK AND ITS TYPE

    OpenAIRE

    Shikha Shukla; Meghana K M; Manjunath C R; SantoshNaik

    2017-01-01

    Wireless network has become one of the major requirements in today world. People expect wireless network in home, shopping mall, university etc. Nowadays, we cannot imagine the life without network. In this paper focuses on what the different types of networks are. Why wired network is preferred over wireless network. We will further compare the wired network with the wireless network and also present different type of wireless network. This paper provides the basic knowledge about Wired, Wir...

  13. IMPLEMENTATION OF WIRED AND WIRELESS NETWORK IN ACADEMIC ENVIRONMENT

    OpenAIRE

    Raman Bhanot*

    2017-01-01

    Formerly, wired network has verified its capabilities but in this day and age wireless communication has emerged as a robust and most intellectual communication technique. Both the types have its own merits and demerits based on its network characteristics. Wired and wireless networking has different hardware necessities, ranges, mobility, reliability and benefits.The aim of the paper is to provide a simulated outlook of Wireless and Wired Network covering whole campus. This simulation has be...

  14. Loss Discrimination Algorithm for Wired/Wireless Networks

    OpenAIRE

    Liw J. Seng; Mohd N. Derahman; Azizol Abdullah

    2011-01-01

    Problem statement: Wireless technology has far growing with an increasing demand of the Wireless networking technologies recent years. The wireless access network and cellular networks are being used to support their need. It is usually connected to a wired backbone network. TCP is used to handle the congestion in wired network. However, it is not well suited for hybrid network consisting of wired and wireless networks. Packet loss occurs in wireless network mostly due to high bit error rate,...

  15. Plasma modes in superconducting wires: Optimized experimental configuration

    Energy Technology Data Exchange (ETDEWEB)

    Camarota, B.; Parage, F.; Wooldridge, I.; Delsing, P.; Buisson, O.

    2000-03-01

    An experimental configuration is analyzed in order to study plasma modes in a superconducting wire deposited onto SrTiO{sub 3}. A dispersion relation has been derived by evaluating the effect of environment surrounding the wire. It corresponds to the one-dimensional dispersion law predicted for an isolated superconducting wire. Preliminary measurements are presented. They show 1D plasma modes in the optimized experimental configuration here studied.

  16. Tungsten quasispherical wire loads with a profiled mass

    Energy Technology Data Exchange (ETDEWEB)

    Grabovskii, E. V.; Dzhangobegov, V. V., E-mail: jvv88@triniti.ru; Oleinik, G. M.; Rodionov, R. N. [State Research Center of the Russian Federation Troitsk Institute for Innovation and Fusion Research (TRINITI) (Russian Federation)

    2015-12-15

    Wire arrays made from micrometer tungsten wires with linear mass profiled along their height are developed for experiments on the generation of X-ray radiation upon pinch compression with a current of ∼3 MA at a pulse duration of ∼100 ns. Wires are imaged with a scanning electron microscope, and their diameter is determined. It is shown that the arrays have such a profile of height distribution of linear mass that allows for compact spherical compression upon current implosion.

  17. The cardiac migration of a Kirschner wire. A case report.

    OpenAIRE

    Anić, D; Brida, V.; Jelić, I; Orlić, D

    1997-01-01

    In June of 1995, a 48-year-old woman was admitted to an outlying hospital with a history of stomach pain several weeks in duration. A few years before, she had undergone orthopedic surgery because of bilateral coxarthrosis. Total endoprosthesis had been implanted at both hips. Chest radiography showed a metal foreign body (apparently a Kirschner wire) in the heart, whereas right-hip radiography showed no Kirschner wire. Echocardiography indicated that the wire was in the right ventricle. The ...

  18. Generation and Analysis of Wire Rope Digital Radiographic Images

    OpenAIRE

    Chakhlov, Sergey Vladimirovich; Anpilogov, P.; Batranin, Andrey Viktorovich; Osipov, Sergey Pavlovich; Zhumabekova, Sh.; Yadrenkin, I.

    2016-01-01

    The paper is dealt with different structures of the digital radiographic system intended for wire rope radiography. The scanning geometry of the wire rope is presented and the main stages of its digital radiographic image generation are identified herein. Correction algorithms are suggested for X-ray beam hardening. A complex internal structure of the wire rope is illustrated by its 25 mm diameter image obtained from X-ray computed tomography. The paper considers the approach to the analysis ...

  19. Filler wire for aluminum alloys and method of welding

    Science.gov (United States)

    Bjorkman, Jr., Gerald W. O. (Inventor); Cho, Alex (Inventor); Russell, Carolyn K. (Inventor)

    2003-01-01

    A weld filler wire chemistry has been developed for fusion welding 2195 aluminum-lithium. The weld filler wire chemistry is an aluminum-copper based alloy containing high additions of titanium and zirconium. The additions of titanium and zirconium reduce the crack susceptibility of aluminum alloy welds while producing good weld mechanical properties. The addition of silver further improves the weld properties of the weld filler wire. The reduced weld crack susceptibility enhances the repair weldability, including when planishing is required.

  20. Modern trends of aircraft fly-by-wire systems

    Directory of Open Access Journals (Sweden)

    Святослав Сергійович Юцкевич

    2013-07-01

    Full Text Available Specifics of civil aviation modern transport aircraft fly-by-wire control systems are described. A comparison of the systems-level hardware and software, expressed through modes of guidance, provision of aircraft Airbus A-320, Boeing B-777, Tupolev Tu-214, Sukhoi Superjet SSJ-100 are carried out. The possibility of transition from mechanical control wiring to control through fly-by-wire system in the backup channel is shown.