Photons uncertainty solves Einstein-Podolsky-Rosen paradox

Einstein, Podolsky and Rosen (EPR) pointed out that the quantum-mechanical description of "physical reality" implied an unphysical, instantaneous action between distant measurements. To avoid such an action at a distance, EPR concluded that Quantum Mechanics had to be incomplete. However, its extensions involving additional "hidden variables", allowing for the recovery of determinism and locality, have been disproved experimentally (Bell's theorem). Here, I present an opposite solution of the paradox based on the greater indeterminism of the modern Quantum Field Theory (QFT) description of Particle Physics, that prevents the preparation of any state having a definite number of particles. The resulting uncertainty in photons radiation has interesting consequences in Quantum Information Theory (e.g. cryptography and teleportation). Moreover, since it allows for less elements of EPR physical reality than the old non-relativistic Quantum Mechanics, QFT satisfies the EPR condition of completeness without the need of hidden variables. The residual physical reality does never violate locality, thus the unique objective proof of "quantum nonlocality" is removed in an interpretation-independent way. On the other hand, the supposed nonlocality of the EPR correlations turns out to be a problem of the interpretation of the theory. If we do not rely on hidden variables or new physics beyond QFT, the unique viable interpretation is a minimal statistical one, that preserves locality and Lorentz symmetry.Comment: Published version, with updated referenc

MESURES D'IMPÉDANCES, DE FONCTIONS DE RÉFLEXION ET D'HARMONICITÉ D'INSTRUMENTS À VENT

La méthode de mesure de l'impédance d'entrée des instruments à vent dite T.M.T.C. que nous avons développé récemment permet grâce à deux mesures simultanées de pression et à une calibration en trois points d'obtenir l'impédance d'entrée d'instruments à vent de diamètres variés avec un seul dispositif de mesure dont les imperfections géométriques acoustiques et électriques sont automatiquement prises en compte. L'utilisation systématique de la micro-informatique et de la saisie numérique permet de disposer d'un outil souple et rapide. Il est ainsi possible de calculer à partir de la mesure d'impédance la fonction de réflexion de l'instrument étudié ainsi que toute autre fonction temporelle. La mesure précise des positions des maximums d'impédance peut également être interprétée en fonction de leur rang et donner une indication sur l'harmonicité ou l'inharmonicité des résonances de l'instrument et donc sur sa qualité.We have developped recently the T.M.T.C method in order to measure the input impedance of woodwinds. This method allows us with a two pressure measurement and a three calibration technic to obtain the impedance of various diameter instruments and to correct a lot of systematics such as geometrical imperfections, microphone admittance, .... The intensive use of micro-computing and numerical acquisition gives us a powerful and fast tool. We are able to compute from the impedance the reflection function or any other time domain function. The knowledge of the frequency position of the impedance peak gives an information of the quality of an instrument by drawing the harmonicity or inharmonicity curve of the instrument

Spontaneous symmetry breaking in vortex systems with two repulsive lengthscales

Scanning Hall probe microscopy (SHPM) has been used to study vortex structures in thin epitaxial films of the superconductor MgB[subscript 2]. Unusual vortex patterns observed in MgB[subscript 2] single crystals have previously been attributed to a competition between short-range repulsive and long-range attractive vortex-vortex interactions in this two band superconductor; the type 1.5 superconductivity scenario. Our films have much higher levels of disorder than bulk single crystals and therefore both superconducting condensates are expected to be pushed deep into the type 2 regime with purely repulsive vortex interactions. We observe broken symmetry vortex patterns at low fields in all samples after field-cooling from above T[subscript c]. These are consistent with those seen in systems with competing repulsions on disparate length scales, and remarkably similar structures are reproduced in dirty two band Ginzburg-Landau calculations, where the simulation parameters have been defined by experimental observations. This suggests that in our dirty MgB[subscript 2] films, the symmetry of the vortex structures is broken by the presence of vortex repulsions with two different lengthscales, originating from the two distinct superconducting condensates. This represents an entirely new mechanism for spontaneous symmetry breaking in systems of superconducting vortices, with important implications for pinning phenomena and high current density applications.United States. Office of Naval Research (Grant N00014-06-01-0235

Stable methylation at promoters distinguishes epiblast stem cells from embryonic stem cells and the in vivo epiblasts

Embryonic Stem Cells (ESCs) and Epiblast Stem Cells (EpiSCs) are the in vitro representatives of naïve and primed pluripotency, respectively. It is currently unclear how their epigenomes underpin the phenotypic and molecular characteristics of these distinct pluripotent states. Here, we performed a genome-wide comparison of DNA methylation between ESCs and EpiSCs by MethylCap-Seq. We observe that promoters are preferential targets for methylation in EpiSC compared to ESCs, in particular high CpG island promoters. This is in line with upregulation of the de novo methyltransferases Dnmt3a1 and Dnmt3b in EpiSC, and downregulation of the demethylases Tet1 and Tet2. Remarkably, the observed DNA methylation signature is specific to EpiSCs and differs from that of their in vivo counterpart, the postimplantation epiblast. Using a subset of promoters that are differentially methylated, we show that DNA methylation is established within a few days during in vitro outgrowth of the epiblast, and also occurs when ESCs are converted to EpiSCs in vitro. Once established, this methylation is stable, as ES-like cells obtained by in vitro reversion of EpiSCs display an epigenetic memory that only extensive passaging and sub-cloning are able to almost completely erase