1,678 research outputs found

    A device-independent protocol for XOR oblivious transfer

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    Oblivious transfer is a cryptographic primitive where Alice has two bits and Bob wishes to learn some function of them. Ideally, Alice should not learn Bob's desired function choice and Bob should not learn any more than what is logically implied by the function value. While decent quantum protocols for this task are known, many become completely insecure if an adversary were to control the quantum devices used in the implementation of the protocol. In this work we give a fully device-independent quantum protocol for XOR oblivious transfer.Comment: Accepted for publication in Quantum. Protocol modified to remove the need for parties to send boxes to each other; new discussion section adde

    Extraction of the electron mass from gg factor measurements on light hydrogenlike ions

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    The determination of the electron mass from Penning-trap measurements with 12^{12}C5+^{5+} ions and from theoretical results for the bound-electron gg factor is described in detail. Some recently calculated contributions slightly shift the extracted mass value. Prospects of a further improvement of the electron mass are discussed both from the experimental and from the theoretical point of view. Measurements with 4^4He+^+ ions will enable a consistency check of the electron mass value, and in future an improvement of the 4^4He nuclear mass and a determination of the fine-structure constant

    Influence of Salinity on the Consistency and Swelling Characteristics of Bentonite

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    Bentonite clay liners are used as a barrier material for water, chemicals and gas in civil engineering structures such as engineered landfills and in structural water proofing. Bentonic clays absorb water and expand greater than any other ordinary plastic clay. The expansiveness of the clay is characterised by the absorbed cation in the clay and the geochemical environment. This paper critically investigates factors that contribute to the swelling characteristics of bentonite clay and its products. It takes particular view on different types of bentonite used in clay liners and their interaction with saline ground water conditions. The swelling pressure of sodium bentonite in deionised water is demonstrated to be very high. However when it is in a saline environment the magnitude of swelling pressure can be less than halved. A parallel observation is noted under conditions of free swell. These are explained as being a consequence of reduction in the double layer thickness which is further reflected in the reduction of cationexchange capacity when the bentonite is in a saline environment. Variations in cation exchange capacity, consistency limit and free swell of the bentonite products in different saline environment are observed and its significance discussed

    Three-dimensional topological lattice models with surface anyons

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    We study a class of three dimensional exactly solvable models of topological matter first put forward by Walker and Wang [arXiv:1104.2632v2]. While these are not models of interacting fermions, they may well capture the topological behavior of some strongly correlated systems. In this work we give a full pedagogical treatment of a special simple case of these models, which we call the 3D semion model: We calculate its ground state degeneracies for a variety of boundary conditions, and classify its low-lying excitations. While point defects in the bulk are confined in pairs connected by energetic strings, the surface excitations are more interesting: the model has deconfined point defects pinned to the boundary of the lattice, and these exhibit semionic braiding statistics. The surface physics is reminiscent of a ν=1/2\nu=1/2 bosonic fractional quantum Hall effect in its topological limit, and these considerations help motivate an effective field theoretic description for the lattice models as variants of bFbF theories. Our special example of the 3D semion model captures much of the behavior of more general `confined Walker-Wang models'. We contrast the 3D semion model with the closely related 3D version of the toric code (a lattice gauge theory) which has deconfined point excitations in the bulk and we discuss how more general models may have some confined and some deconfined excitations. Having seen that there exist lattice models whose surfaces have the same topological order as a bosonic fractional quantum Hall effect on a confining bulk, we construct a lattice model whose surface has similar topological order to a fermionic quantum hall effect. We find that in these models a fermion is always deconfined in the three dimensional bulk

    Access to improve the muon mass and magnetic moment anomaly via the bound-muon gg factor

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    A theoretical description of the gg factor of a muon bound in a nuclear potential is presented. One-loop self-energy and multi-loop vacuum polarization corrections are calculated, taking into account the interaction with the binding potential exactly. Nuclear effects on the bound-muon gg factor are also evaluated. We put forward the measurement of the bound-muon gg factor via the continuous Stern-Gerlach effect as an independent means to determine the free muons magnetic moment anomaly and mass. The scheme presented enables to increase the accuracy of the mass by more than an order of magnitude

    Theory of the two-loop self-energy correction to the g factor in nonperturbative Coulomb fields

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    Two-loop self-energy corrections to the bound-electron gg factor are investigated theoretically to all orders in the nuclear binding strength parameter ZαZ\alpha. The separation of divergences is performed by dimensional regularization, and the contributing diagrams are regrouped into specific categories to yield finite results. We evaluate numerically the loop-after-loop terms, and the remaining diagrams by treating the Coulomb interaction in the electron propagators up to first order. The results show that such two-loop terms are mandatory to take into account for projected near-future stringent tests of quantum electrodynamics and for the determination of fundamental constants through the gg factor

    Two-loop virtual light-by-light scattering corrections to the bound-electron g factor

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    A critical set of two-loop quantum electrodynamics corrections to the g factor of hydrogenlike ions is calculated in the Furry picture. These corrections are due to the polarization of the external magnetic field by the quantum vacuum, which is dressed by the binding field. The result obtained for the self-energy–magnetic-loop diagrams is compared with the current state-of-the-art result, derived through a perturbative expansion in the binding strength parameter Zα, with Z the atomic number and α the fine-structure constant. Agreement is found in the Z→0 limit. However, even for very light ions, the perturbative result fails to approximate the magnitude of the corresponding correction to the g factor. The total correction to the g factor coming from all diagrams considered in this work is found to be highly relevant for upcoming experimental tests of fundamental physics with highly charged ions

    QED corrections to the g factor of Li- and B-like ions

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    QED corrections to the gg factor of Li-like and B-like ions in a wide range of nuclear charges are presented. Many-electron contributions as well as radiative effects on the one-loop level are calculated. Contributions resulting from the interelectronic interaction, the self-energy effect, and most of the terms of the vacuum-polarization effect are evaluated to all orders in the nuclear coupling strength ZαZ\alpha. Uncertainties resulting from nuclear size effects, numerical computations, and uncalculated effects are discussed
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