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Experimental study of μ-atomic and μ-molecular processes in pure helium and deuterium-helium mixtures

Physical Review A 2005年第3期71卷 032723-032723页

作者： V. M. Bystritsky V. F. Boreiko W. Czapliński M. Filipowicz V. V. Gerasimov O. Huot P. E. Knowles F. Mulhauser V. N. Pavlov N. P. Popov L. A. Schaller H. Schneuwly V. G. Sandukovsky V. A. Stolupin V. P. Volnykh J. Woźniak Joint Institute for Nuclear Research Dubna 141980 Russia AGH University of Science and Technology Faculty of Physics and Applied Computer Science PL-30059 Cracow Poland AGH University of Science and Technology Faculty of Fuels and Energy PL-30059 Cracow Poland Department of Physics University of Fribourg CH-1700 Fribourg Switzerland University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA

We present experimental results of μ-atomic and μ-molecular processes induced by negative muons in pure helium and helium-deuterium mixtures. The experiment was performed at the Paul Scherrer Institute (Switzerland). We measured relative intensities of muonic x-ray K series transitions in (μHe3,4)* atoms in pure helium as well as in helium-deuterium mixtures. The dμHe3 radiative decay probabilities for two different helium densities in D2+He3 mixture were also determined. Finally, the q1sHe probability for a dμ atom formed in an excited state to reach the ground state was measured and compared with theoretical calculations using a simple cascade model.

关键词： EXCITED MUONIC HYDROGEN LIGHT EXOTIC ATOMS ONE-ELECTRON ATOMS NUCLEAR-FUSION DECAY-RATES CASCADE PROCESSES CATALYZED FUSION NEGATIVE MUONS KINETIC ENERGIES RADIATIVE DECAY

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Locking Entanglement with a Single Qubit

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Physical Review Letters 2005年第20期94卷 200501-200501页

作者： Karol Horodecki Michał Horodecki Paweł Horodecki Jonathan Oppenheim Department of Mathematics Physics and Computer Science University of Gdańsk 80–952 Gdańsk Poland Institute of Theoretical Physics and Astrophysics University of Gdańsk 80–952 Gdańsk Poland Faculty of Applied Physics and Mathematics Technical University of Gdańsk 80–952 Gdańsk Poland Department of Applied Mathematics and Theoretical Physics University of Cambridge Cambridge United Kingdom

We study the loss of entanglement of a bipartite state subjected to discarding or measurement of one qubit. Examining behavior of different entanglement measures, we find that entanglement of formation, entanglement cost, logarithmic negativity, and one-way distillable entanglement are lockable measures in that they can decrease arbitrarily after measuring one qubit. We prove that any convex and asymptotically noncontinuous measure is lockable. As a consequence, all the convex-roof measures can be locked. The relative entropy of entanglement is shown to be a nonlockable measure.

关键词： Quantum theory

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Secure Key from Bound Entanglement

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Physical Review Letters 2005年第16期94卷 160502-160502页

作者： Karol Horodecki Michał Horodecki Paweł Horodecki Jonathan Oppenheim Department of Mathematics Physics and Computer Science University of Gdańsk Poland Institute of Theoretical Physics and Astrophysics University of Gdańsk Poland Faculty of Applied Physics and Mathematics Technical University of Gdańsk 80-952 Gdańsk Poland Department of Applied Mathematics and Theoretical Physics University of Cambridge Cambridge United Kingdom Racah Institute of Theoretical Physics Hebrew University of Jerusalem Givat Ram Jerusalem 91904 Israel

We characterize the set of shared quantum states which contain a cryptographically private key. This allows us to recast the theory of privacy as a paradigm closely related to that used in entanglement manipulation. It is shown that one can distill an arbitrarily secure key from bound entangled states. There are also states that have less distillable private keys than the entanglement cost of the state. In general, the amount of distillable key is bounded from above by the relative entropy of entanglement. Relationships between distillability and distinguishability are found for a class of states which have Bell states correlated to separable hiding states. We also describe a technique for finding states exhibiting irreversibility in entanglement distillation.

关键词： Quantum cryptography

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Abstracts from the 6th International Conference on the Engineering of Sport, 10-14 July 2006, Olympic Hall, Munich, Germany Abstracts

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SPORTS ENGINEERING 2006年第4期9卷 229-249页

作者： [Anonymous] TNO Netherlands Delcam plc UK Technological Institute of Toys AIJU Spain Technische Universitaet Muenchen Germany Hochschule für Gestaltung und Kunst Zuerich Germany Otto-v.-Guericke-University Magdeburg Germany AISTS-International Academy of Sports Science and Technology Lausanne Switzerland CSEM-Swiss Center for Electronics and Microtechnology Neuchâtel Swizerland University of Illinois at Urbana-Champaign USA Delft University of Technology Netherlands Faculty of Education Art and Science Yamagata University Japan Department of Mathematical Modelling Perm State Technical University Russia Department of Theoretical Mechanics Perm State Technical University Russia Department of Computational Fluid Dynamics JSC Aviadvigatel Perm Motors Russia Mechanical and Automotive Engineering RMIT University Japan Fluent Europe Ltd Sheffield UK SportKreativWerkstatt GmbH München Germany Sports Technology Research Group Loughborough University UK Department of Mechanical Engineering University of Bath UK Instituto de Biomecánica de Valencia (IBV) Spain University Augsburg UK Sports Engineering Research Group University of Sheffield England Sports-Equipment Technology Technikum Wien Austria Fischer GmbH Germany Biocompatible Materials and Process Engineering TU Munich Germany The University of Waikato New Zealand Sandvik Materials Technology Sweden Institute for Machine Tools and Industrial Management TU Munich Germany Institut fuer Verbundwerkstoffe GmbH Canada Sports Engineering Centre for Sports and Exercise Science Sheffield Hallam University England University of Glamorgan UK Department of Information Science and Engineering Tokyo Institute of Technology Tokyo Japan Toyota Motor Co. Aichi Japan Iowa Univeristy Iowa USA Simbex Lebanon USA Japan Institute of Sports Sciences Tokyo Japan University of Vienna Austria Technische Universität München Germany Department of Econometrics University of Groningen The Netherlands Department of Physical Education and Sport

A radical change (Feenstra, Holmer, Tromans, Moos and Mieritz 2003) in manufacturing is starting to occur. The Rapid Manufacturing, which can be defined as "the use of an additive manufacturing process to construct parts that are used directly as finished products or components", is set to supersede many current uses of moulds and dies. Rapid Manufacturing (Wohlers 2003) is based on new additive manufacturing techniques that produce fully functional parts directly from a 3D CAD model without the use of tooling. The ambitious scope of the European Initiative CUSTOM-FIT, a Framework 6 Integrated Project, is to create a fully integrated system for the design, production and supply of individualized custom-products. Within the cases under study there are strong connections to sporting articles. This project is being funded by the European Commission over the next four years and a half and will become central to European research concerning Rapid Manufacturing (RM).

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Few-electron eigenstates of concentric double quantum rings

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Physical Review B 2005年第15期72卷 155316-155316页

作者： B. Szafran F. M. Peeters Departement Fysica Universiteit Antwerpen Groenenborgerlaan 171 B-2020 Antwerpen Belgium Faculty of Physics and Applied Computer Science AGH University of Science and Technology al. Mickiewicza 30 30-059 Kraków Poland

Few-electron eigenstates confined in coupled concentric double quantum rings are studied by the exact diagonalization technique. We show that the magnetic field suppresses the tunnel coupling between the rings, localizing the single-electron states in the internal ring and the few-electron states in the external ring. The magnetic fields inducing the ground-state angular momentum transitions are determined by the distribution of the electron charge between the rings. The charge redistribution is translated into modifications of the fractional Aharonov-Bohm period. We demonstrate that the electron distribution can be deduced from the cusp pattern of the chemical potentials governing the single-electron charging properties of the system. The evolution of the electron-electron correlations to the high field limit of a classical Wigner molecule is discussed.

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Three electrons in laterally coupled quantum dots: Tunnel vs electrostatic coupling, ground-state symmetry, and interdot correlations

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Physical Review B 2005年第24期71卷 245314-245314页

作者： B. Szafran F. M. Peeters Departement Fysica Universiteit Antwerpen (Campus Drie Eiken) B-2610 Antwerpen Belgium Faculty of Physics and Applied Computer Science AGH University of Science and Technology al. Mickiewicza 30 30-059 Kraków Poland

The phase diagram for the ground-state symmetry of three electrons confined in a pair of laterally coupled dots is determined as function of the interdot distance and the magnetic field. With a few exceptions the ground-state spin and parity symmetry sequence of a circular harmonic quantum dot is conserved. Reentrant behavior of some energy levels as ground states is found as a function of the magnetic field. The disappearance of interdot tunnelling due to a strong magnetic field leads to ground-state degeneracy of the even and odd parity energy levels. It is shown that at a high magnetic field the system can be closely approximated by a two-electron system confined in one dot and a spectator electron localized in the other. Broken-parity eigenstates with a classical charge distribution are constructed and used to discuss the interdot electron-electron correlations.

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Time-dependent simulations of electron transport through a quantum ring: Effect of the Lorentz force

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Physical Review B 2005年第16期72卷 165301-165301页

作者： B. Szafran F. M. Peeters Departement Fysica Universiteit Antwerpen (Campus Drie Eiken) Universiteitsplein 1 B-2610 Antwerpen Belgium Faculty of Physics and Applied Computer Science AGH University of Science and Technology aleja Mickiewicza 30 30-059 Kraków Poland

The time-dependent Schrödinger equation for an electron passing through a semiconductor quantum ring of nonzero width is solved in the presence of a perpendicular homogeneous magnetic field. We study the effects of the Lorentz force on the Aharonov-Bohm oscillations. Within the range of incident momentum for which the ring is transparent at zero magnetic field, the Lorentz force leads to a decrease of the oscillation amplitude, due to the asymmetry in the electron injection in the two arms of the ring. For structures in which the fast electrons are predominantly backscattered, the Lorentz force assists in the transport, producing an initial increase of the corresponding oscillation amplitude. Furthermore, we discuss the effect of elastic scattering on a potential cavity within one of the arms of the ring. For the cavity tuned to shift maximally the phase of the maximum of the wave packet we observe a π shift of the Aharonov-Bohm oscillations. For other cavity depths oscillations with a period of half of the flux quantum are observed.

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Relative stability of negative and positive trions in model symmetric quantum wires

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Physical Review B 2005年第23期71卷 235305-235305页

作者： B. Szafran T. Chwiej F. M. Peeters S. Bednarek J. Adamowski Departement Fysica Universiteit Antwerpen (Campus Drie Eiken) Universiteitsplein 1 B-2610 Antwerpen Belgium Faculty of Physics and Applied Computer Science AGH University of Science and Technology al. Mickiewicza 30 30-059 Kraków Poland

Binding energies of negative (X−) and positive trions (X+) in quantum wires are studied for strong quantum confinement of carriers which results in a numerical exactly solvable model. The relative electron and hole confinement have a strong effect on the stability of trions. For equal hole and electron confinement, X+ is more stable but a small imbalance of the particle confinement towards a stronger hole confinement, e.g., due to its larger effective mass, leads to the interchange of X− and X+ recombination lines in the photoluminescent spectrum as was recently observed experimentally. In case of larger X− stability, a magnetic field oriented parallel to the wire axis leads to a stronger increase of the X+ binding energy resulting in a crossing of the X+ and X− lines.

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Exciton and negative trion dissociation by an external electric field in vertically coupled quantum dots

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Physical Review B 2005年第20期71卷 205316-205316页

作者： B. Szafran T. Chwiej F. M. Peeters S. Bednarek J. Adamowski B. Partoens Departement Fysica Universiteit Antwerpen (Campus Drie Eiken) Universiteitsplein 1 B-2610 Antwerpen Belgium Faculty of Physics and Applied Computer Science AGH University of Science and Technology al. Mickiewicza 30 30-059 Kraków Poland

We study the Stark effect for an exciton confined in a pair of vertically coupled quantum dots. A single-band approximation for the hole and a parabolic lateral confinement potential are adopted which allows for the separation of the lateral center-of-mass motion and consequently for an exact numerical solution of the Schrödinger equation. We show that for intermediate tunnel coupling the external electric field leads to the dissociation of the exciton via an avoided crossing of bright and dark exciton energy levels which results in an atypical form of the Stark shift. The electric-field-induced dissociation of the negative trion is studied using the approximation of frozen lateral degrees of freedom. It is shown that in a symmetric system of coupled dots the trion is more stable against dissociation than the exciton. For an asymmetric system of coupled dots the trion dissociation is accompanied by a positive curvature of the recombination energy line as a function of the electric field.

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Transport in doped skutterudites: Ab initio electronic structure calculations

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Physical Review B 2005年第8期72卷 085126-085126页

作者： L. Chaput P. Pécheur J. Tobola H. Scherrer Laboratoire de Physique des Matériaux UMR 75560 ENSMN Parc de Saurupt 54042 Nancy France Faculty of Physics and Applied Computer Science AGH University of Science and Technology Aleja Mickiewicza 30 30-059 Cracow Poland

We present ab initio calculations of conductivity, thermopower, Lorenz factor, and Hall coefficient for doped cobalt antimony skutterudites which are currently investigated experimentally for their thermoelectric properties. The electronic structure is calculated by the full potential linear augmented-plane-wave method. Using the results and shifting the Fermi level in a rigid way to mimic doping, Onsager coefficients are calculated in the framework of Boltzmann transport theory with a constant relaxation time. To this end electron velocities are calculated using a spectral collocation method. These results compare favorably with experiments.

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