4,029 research outputs found

    Pettis integrability of fuzzy mappings with values in arbitrary Banach spaces

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    In this paper we study the Pettis integral of fuzzy mappings in arbitrary Banach spaces. We present some properties of the Pettis integral of fuzzy mappings and we give conditions under which a scalarly integrable fuzzy mapping is Pettis integrable

    Impact of classical forces and decoherence in multi-terminal Aharonov-Bohm networks

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    Multi-terminal Aharonov-Bohm (AB) rings are ideal building blocks for quantum networks (QNs) thanks to their ability to map input states into controlled coherent superpositions of output states. We report on experiments performed on three-terminal GaAs/Al_(x)Ga_(1-x)As AB devices and compare our results with a scattering-matrix model including Lorentz forces and decoherence. Our devices were studied as a function of external magnetic field (B) and gate voltage at temperatures down to 350 mK. The total output current from two terminals while applying a small bias to the third lead was found to be symmetric with respect to B with AB oscillations showing abrupt phase jumps between 0 and pi at different values of gate voltage and at low magnetic fields, reminiscent of the phase-rigidity constraint due to Onsager-Casimir relations. Individual outputs show quasi-linear dependence of the oscillation phase on the external electric field. We emphasize that a simple scattering-matrix approach can not model the observed behavior and propose an improved description that can fully describe the observed phenomena. Furthermore, we shall show that our model can be successfully exploited to determine the range of experimental parameters that guarantee a minimum oscillation visibility, given the geometry and coherence length of a QN.Comment: 7 pages, 8 figure

    Nonlinear double Compton scattering in the full quantum regime

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    A detailed analysis of the process of two photon emission by an electron scattered from a high-intensity laser pulse is presented. The calculations are performed in the framework of strong-field QED and include exactly the presence of the laser field, described as a plane wave. We investigate the full quantum regime of interaction, where photon recoil plays an essential role in the emission process, and substantially alters the emitted photon spectra as compared to those in previously-studied regimes. We provide a semiclassical explanation for such differences, based on the possibility of assigning a trajectory to the electron in the laser field before and after each quantum photon emission. Our numerical results indicate the feasibility of investigating experimentally the full quantum regime of nonlinear double Compton scattering with already available plasma-based electron accelerator and laser technology.Comment: 5 pages, 3 figure

    Sub-eV scalar dark matter through the super-renormalizable Higgs portal

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    The Higgs portal of the Standard Model provides the opportunity for coupling to a very light scalar field ϕ\phi via the super-renormalizable operator ϕ(HH)\phi(H^\dagger H). This allows for the existence of a very light scalar dark matter that has coherent interaction with the Standard Model particles and yet has its mass protected against radiative corrections. We analyze ensuing constraints from the fifth-force measurements, along with the cosmological requirements. We find that the detectable level of the fifth-force can be achieved in models with low inflationary scales, and certain amount of fine-tuning in the initial deviation of ϕ\phi from its minimum.Comment: 6 pages, 3 figures. References added in the revised version

    An integrated approach project for the revaluation of a traditional sourdough bread production chain

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    The influence of organic and conventional farming systems on the performance of a panel of old and modern Italian bread wheat varieties has been evaluated, with the aim to individuate an agronomic protocol suitable for the production of a sourdough bread traditionally prepared in a hill zone of Emilia-Romagna. The agronomic and technological characterisation of the wheat samples obtained in organic and conventional farming conditions has been done and the sensorial qualities of the sourdough bread obtained have been evaluated

    Electronic implementations of Interaction-Free Measurements

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    Three different implementations of interaction-free measurements (IFMs) in solid-state nanodevices are discussed. The first one is based on a series of concatenated Mach-Zehnder interferometers, in analogy to optical-IFM setups. The second one consists of a single interferometer and concatenation is achieved in the time domain making use of a quantized electron emitter. The third implementation consists of an asymmetric Aharonov-Bohm ring. For all three cases we show that the presence of a dephasing source acting on one arm of the interferometer can be detected without degrading the coherence of the measured current. Electronic implementations of IFMs in nanoelectronics may play a fundamental role as very accurate and noninvasive measuring schemes for quantum devices.Comment: 12 pages, 10 figure

    Le retoriche della concordia

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    L'uso dell'espressione “Les rhétoriques de la concorde”, è la conseguenza di una scelta ben precisa: attribuire una funzione politica al genere epidittico. A questa scelta si possono opporre delle critiche legittime, tenuto conto che le fonti antiche presentano i discorsi epidittici come discorsi di circostanza che ruotano attorno alle nozioni di elogio e di biasimo. L’idea di una funzione politica del genere epidittico si fonda su un’interpretazione inizialmente proposta da Perelman e Olbrechts-Tyteca. A partire da questo - e alla luce dei contributi che la curatela raccoglie - gli autori ragionano sul nesso inscindibile epidittico/politica.The expression "Les rhétoriques de la concorde", is the consequence of a precise choice: assigning a political function to the epideictic genre. This choice can be opposed to legitimate criticism, given that the ancient sources present the epidemic discourses as discourses on circumstance that revolve around the praise and the blame. The idea of a political function of the epidemic type is based on an interpretation initially proposed by Perelman and Olbrechts-Tyteca. Starting from this - and in the light of the contributions that the editors collect - the authors reason about the inseparable epidictic/political link

    Coulomb-Blockade directional coupler

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    A tunable directional coupler based on Coulomb Blockade effect is presented. Two electron waveguides are coupled by a quantum dot to an injector waveguide. Electron confinement is obtained by surface Schottky gates on single GaAs/AlGaAs heterojunction. Magneto-electrical measurements down to 350 mK are presented and large transconductance oscillations are reported on both outputs up to 4.2 K. Experimental results are interpreted in terms of Coulomb Blockade effect and the relevance of the present design strategy for the implementation of an electronic multiplexer is underlined.Comment: 4 pages, 4 figures, to be published in Applied Physics Letter

    Apparatus for time‐resolved measurements of acoustic birefringence in particle dispersions

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    An apparatus for time‐resolved measurements of the birefringence induced in a particle suspension by an acoustic wave pulse is described. Efficient acoustic coupling is obtained by operating near the transducer resonant frequency and by matching the acoustic impedances of the cell constituents. An almost‐overdamped acoustic configuration can alternatively be employed whenever a faster response is needed. Careful design of the optical setup and of the detection unit minimize diffraction and stress‐birefringence parasitic effects and yields a good responsivity at fairly low acoustic intensities. A test of the apparatus on a colloidal suspension of PTFE rodlike particles is presented and discussed
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