Full quantum mechanical analysis of atomic three-grating Mach-Zehnder interferometry

17 págs.; 6 figs.© 2014 Elsevier Inc. Atomic three-grating Mach-Zehnder interferometry constitutes an important tool to probe fundamental aspects of the quantum theory. There is, however, a remarkable gap in the literature between the oversimplified models and robust numerical simulations considered to describe the corresponding experiments. Consequently, the former usually lead to paradoxical scenarios, such as the wave-particle dual behavior of atoms, while the latter make difficult the data analysis in simple terms. Here these issues are tackled by means of a simple grating working model consisting of evenly-spaced Gaussian slits. As is shown, this model suffices to explore and explain such experiments both analytically and numerically, giving a good account of the full atomic journey inside the interferometer, and hence contributing to make less mystic the physics involved. More specifically, it provides a clear and unambiguous picture of the wavefront splitting that takes place inside the interferometer, illustrating how the momentum along each emerging diffraction order is well defined even though the wave function itself still displays a rather complex shape. To this end, the local transverse momentum is also introduced in this context as a reliable analytical tool. The splitting, apart from being a key issue to understand atomic Mach-Zehnder interferometry, also demonstrates at a fundamental level how wave and particle aspects are always present in the experiment, without incurring in any contradiction or interpretive paradox. On the other hand, at a practical level, the generality and versatility of the model and methodology presented, makes them suitable to attack analogous problems in a simple manner after a convenient tuning.Support from the Ministerio de Economía y Competitividad (Spain) under Project No. FIS2011-29596-C02-01 (AS) as well as a ‘‘Ramón y Cajal’’ Research Fellowship with Ref. RYC-2010-05768 (AS), and the Ministry of Education, Science and Technological Development of Serbia under Projects Nos. OI171005 (MB), OI171028 (MD), and III45016 (MB, MD) is acknowledged.Peer Reviewe

Inverse mass matrix via the method of localized lagrange multipliers

An efficient method for generating the mass matrix inverse is presented, which can be tailored to improve the accuracy of target frequency ranges and/or wave contents. The present method bypasses the use of biorthogonal construction of a kernel inverse mass matrix that requires special procedures for boundary conditions and free edges or surfaces, and constructs the free-free inverse mass matrix employing the standard FEM procedure. The various boundary conditions are realized by the method of localized Lagrange multipliers. Numerical experiments with the proposed inverse mass matrix method are carried out to validate the effectiveness proposed technique when applied to vibration analysis of bars and beams. A perfect agreement is found between the exact inverse of the mass matrix and its direct inverse computed through biorthogonal basis functions

Quantumness beyond quantum mechanics

Bohmian mechanics allows us to understand quantum systems in the light of other quantum traits than the well-known ones (coherence, diffraction, interference, tunneling, discreteness, entanglement, etc.). Here the discussion focusses precisely on two of these interesting aspects, which arise when quantum mechanics is though within this theoretical framework: the non-crossing property, which allows for distinguishability without erasing interference patterns, and the possibility to define quantum probability tubes, along which the probability remains constant all the way. Furthermore, taking into account this hydrodynamic-like description as a link, it is also shown how this knowledge (concepts and ideas) can be straightforwardly transferred to other fields of physics (for example, the transmission of light along waveguides).Comment: 11 pages, 4 figures; based on a talk at the Conference "Emergent Quantum Mechanics" / 5th Heinz von Foerster Congress (Vienna, Nov 11-13, 2011

Social Construction of Health Risk: Rhetorical Elements in Colombian and U.S. News Coverage of Coca Eradication

This paper examines rhetorical elements related to the social construction of health risk. More specifically, we analyze how prominent Colombian and U.S. newspapers construct the health risks associated with the use of glyphosate in the “war on drugs” in Colombia. Glyphosate, an herbicide that works as a plant growth regulator, is used heavily via aerial spraying to eradicate Colombian coca cultivation: use mandated by Plan Colombia. These practices have generated wide ranging cultural and sociopolitical disputes among environmental, health, communal, and political organizations. While our focus is on the controversy related to health issues, our analyses necessarily touch on various environmental, community, and political issues

Coherence loss and revivals in atomic interferometry: A quantum-recoil analysis

The coherence effects induced by external photons coupled to matter waves inside a MachZehnder three-grating interferometer are analyzed. Alternatively to atomphoton entanglement scenarios, the model considered here only relies on the atomic wavefunction and the momentum shift induced in it by the photon scattering events. A functional dependence is thus found between the observables, namely the fringe visibility and the phase shift, and the transversal momentum transfer distribution. Good quantitative agreement is found when comparing the results obtained from our model with the experimental data. © 2012 IOP Publishing Ltd.MD, MB and DA acknowledge support from the Ministry of Science of Serbia under Projects OI171005, OI171028 and III45016. ASS acknowledges support from the Ministerio de Econom´ıa y Competitividad (Spain) under Projects FIS2010-22082 and FIS2010-29596-C02-01, as well as for a “Ram´on y Cajal” Research Fellowship.Peer Reviewe

Loss of coherence in double-slit diffraction experiments

7 págs.; 3 figs.; PACS numberssd: 03.65.Yz, 03.65.Ta, 03.75.DgThe effects of incoherence and decoherence in a double-slit experiment are studied using both optical and quantum-phenomenological models. The results are compared with experimental data obtained with cold neutrons. ©2005 American Physical SocietyThis work was supported in part by MCyT Spaind under Contracts No. BFM2000-347 and No. BQU2003-8212. A.S.S. gratefully acknowledges partial support from the Consejería de Educación y Cultura of the Comunidad Autónoma de Madrid.Peer Reviewe

3D Simulations of Relativistic Precessing Jets Probing the Structure of Superluminal Sources

We present the results of a three-dimensional, relativistic, hydrodynamic simulation of a precessing jet into which a compact blob of matter is injected. A comparison of synthetic radio maps computed from the hydrodynamic model, taking into account the appropriate light travel time delays, with those obtained from observations of actual superluminal sources shows that the variability of the jet emission is the result of a complex combination of phase motions, viewing angle selection effects, and non-linear interactions between perturbations and the underlying jet and/or the external medium. These results question the hydrodynamic properties inferred from observed apparent motions and radio structures, and reveal that shock-in-jet models may be overly simplistic.Comment: Accepted for publication in ApJL. 4 pages, 5 figures (4 in color

Analysis of <SUP>63,65</SUP>Cu(<SUP>3</SUP>He, d)<SUP>64,66</SUP>Zn reaction in the unified model

An analysis of the experimental spectroscopic factors involved in the 63,65Cu(3He, d)64,66Zn reactions is proposed within the intermediate-coupling approach in the unified model.Facultad de Ciencias Exacta

Nonadiabaticity of beta-vibrations in the Davydov model

The feasibility of an adiabatic treatment of beta vibrations for even-even rare-earth nuclei is investigated with the restricted formula of Davydov. The parameters gamma and mu as deduced from the fitting of experimental data with Davydov-Chaban predictions are used as zeroth-order approximation. For all the considered nuclei, at a certain stage of the iterative process, the parameters got out of the range of validity of the restricted formula. Taking into account the values of those parameters for other regions of the periodic table, the conclusion can be drawn that an adiabatic treatment of beta vibrations within the frame of the Davydov model cannot be made.Facultad de Ciencias Exacta

Making ARPES Measurements on Corrugated Monolayer Crystals: Suspended Exfoliated Single-Crystal Graphene

Free-standing exfoliated monolayer graphene is an ultra-thin flexible membrane, which exhibits out of plane deformation or corrugation. In this paper, a technique is described to measure the band structure of such free-standing graphene by angle-resolved photoemission. Our results show that photoelectron coherence is limited by the crystal corrugation. However, by combining surface morphology measurements of the graphene roughness with angle-resolved photoemission, energy dependent quasiparticle lifetime and bandstructure measurements can be extracted. Our measurements rely on our development of an analytical formulation for relating the crystal corrugation to the photoemission linewidth. Our ARPES measurements show that, despite significant deviation from planarity of the crystal, the electronic structure of exfoliated suspended graphene is nearly that of ideal, undoped graphene; we measure the Dirac point to be within 25 meV of $E_F$ . Further, we show that suspended graphene behaves as a marginal Fermi-liquid, with a quasiparticle lifetime which scales as $(E - E_F)^{-1}$; comparison with other graphene and graphite data is discussed