Thesis Chapters by François Barriquand
Du point de vue de la philosophie des sciences, la liberté humaine semble énigmatique. Du point d... more Du point de vue de la philosophie des sciences, la liberté humaine semble énigmatique. Du point de vue de la logique, paradoxale. Du point de vue de la foi chrétienne, mystérieuse. N'est-elle pas effectivement tout cela à la fois ?
Papers by François Barriquand
Http Www Theses Fr, 1991
Nous avons etudie l'anisotropie des proprietes rmn de l'oxygene 17 dans les oxydes suprac... more Nous avons etudie l'anisotropie des proprietes rmn de l'oxygene 17 dans les oxydes supraconducteurs a haute temperature critique. Nos mesures nous ont permis de comparer les caracteristiques microscopiques de la susceptibilite statique et de la susceptibilite dynamique dans de tels materiaux. Nous avons montre que, dans la phase metallique faiblement dopee, le temps de relaxation spin-reseau sur l'oxygene des plans suggerait l'existence de deux degres de liberte electroniques
Abstract We have measured the Knight shift and the spin-lattice relaxation of the O(2, 3) planar ... more Abstract We have measured the Knight shift and the spin-lattice relaxation of the O(2, 3) planar sites in a single crystal of YBa 2 Cu 3 O 6.5 . We report the anisotropy of these quantities, together with their striking temperature dependences. Our data are not easy to understand in any theoretical model presently available. One approach is to consider the T 1 data to indicate that, for temperatures greater than T c , some electronic fluctuations develop prefertially on the O(2p) orbitals, and not on the Cu(3d) orbitals. However, such an analysis seems incompatible at first sight with our Knight shift data, because the planar oxygen Knight shift tensor appears to result from a single electronic susceptibility and not two different susceptibilities. We, however, propose an alternative “two-fluid” model analysis which may account qualitatively for the NMR features observed. The originality of our experimental work, if compared with some other, lies to a large extent in our ability to take advantage of the possibilities offered by a 17 O-enriched single crystal study.
viXra, 2020
A variant of the well-known Einstein-Podolski-Rosen experiment is proposed, in which two protagon... more A variant of the well-known Einstein-Podolski-Rosen experiment is proposed, in which two protagonists may communicate in a way that constitutes a strong challenge for the most commonly accepted interpretation of the EPR experiment.
Physica C-superconductivity and Its Applications - PHYSICA C, 1990
A contribution to superexchange coming from empty oxygen orbitals is pointed out. We also estimat... more A contribution to superexchange coming from empty oxygen orbitals is pointed out. We also estimate the small anisotropy of the in-plane superexchange, as well as the superexchange between two adjacent layers in the specific ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6}$ compound. In doped compounds, we improve the description of the transport properties of Zhang-Rice singlets over the simple t-J model. Particularly important for the bandwidth is the role of what we call ${\mathrm{t}}_{\mathrm{unequal}\mathrm{}\mathrm{spins}}^{\ensuremath{'}}$ and ${\mathrm{t}}_{\mathrm{unequal}\mathrm{}\mathrm{spins}}^{\mathrm{\ensuremath{''}}}$. When more than one doped hole is present in the system, the interaction between holes becomes rapidly non-negligible: two Zhang-Rice singlets placed on neighboring cells highly repel each other. Some aspects of oxygen spin dynamics are discussed, in connection with NMR experiments.
A modified version of Leo Szilard's 1929 thought-experiment is considered, which allows one ... more A modified version of Leo Szilard's 1929 thought-experiment is considered, which allows one to show that the iteration of some specially conceived thermodynamic “cycles ” does not require any costly memory erasure. These thermodynamic cycles can be easily examined from either a classical or a quantum point of view. Although they differ randomly from each other in certain aspects, their remarkable energy balance remains systematically constant. Similar cycles can prove useful for lowering the theoretical cost of memory erasure in computers.
viXra, 2020
A variant of the well-known Einstein-Podolski-Rosen experiment is proposed, in which two protagon... more A variant of the well-known Einstein-Podolski-Rosen experiment is proposed, in which two protagonists may communicate in a way that constitutes a strong challenge for the most commonly accepted interpretation of the EPR experiment.
viXra, 2010
Three articles published by the same author in the Revue des Questions Scientifiques in 2005 and ... more Three articles published by the same author in the Revue des Questions Scientifiques in 2005 and 2006 are reexamined with special attention paid to a theorem published by Allahverdyan and Nieuwenhuizen in 2002 concerning Thomson's formulation of the second law, as well as to the results of the so-called "before-before" experiment performed on entangled pairs by Stefanov, Zbinden, Gisin and Suarez. As far as thermodynamics are concerned, it is explained here that a macroscopic observer can generate quasi "cycles", whose cyclical characteristics are in fact only valid from the macroscopic point of view, that can potentially enable her/him to retrieve work from a thermalizer without causing any perpetual motion. Concerning quantum entanglement, it is recognized - in contrast with what the author originally published in 2005 and 2006 - that superluminal transmission of decipherable information cannot be achieved if the Copenhagen interpretation of quantum theory ...
The question of freedom is one of the central issues of the dialogue between science and religion... more The question of freedom is one of the central issues of the dialogue between science and religion. Here, a multi-disciplinary approach is used to analyze the nature of freedom. Special attention is devoted to its ontological status. Scientific, philosophical and theological points of view are successively presented. Special attention is paid to the articulation between different approaches, so that the specificity of each is respected.
A contribution to superexchange coming from empty oxygen orbitals is pointed out. We also estimat... more A contribution to superexchange coming from empty oxygen orbitals is pointed out. We also estimate the small anisotropy of the in-plane superexchange, as well as the superexchange between two adjacent layers in the specific ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6}$ compound. In doped compounds, we improve the description of the transport properties of Zhang-Rice singlets over the simple t-J model. Particularly important for the bandwidth is the role of what we call ${\mathrm{t}}_{\mathrm{unequal}\mathrm{}\mathrm{spins}}^{\ensuremath{'}}$ and ${\mathrm{t}}_{\mathrm{unequal}\mathrm{}\mathrm{spins}}^{\mathrm{\ensuremath{''}}}$. When more than one doped hole is present in the system, the interaction between holes becomes rapidly non-negligible: two Zhang-Rice singlets placed on neighboring cells highly repel each other. Some aspects of oxygen spin dynamics are discussed, in connection with NMR experiments.
A modified version of Leo Szilard's 1929 thought-experiment is considered, which allows one t... more A modified version of Leo Szilard's 1929 thought-experiment is considered, which allows one to show that the iteration of some specially conceived thermodynamic “cycles” does not require any costly memory erasure. These thermodynamic cycles can be easily examined from either a classical or a quantum point of view. Although they differ randomly from each other in certain aspects, their remarkable energy balance remains systematically constant. Similar cycles can prove useful for lowering the theoretical cost of memory erasure in computers.
A special statistical model illustrates how an object can move anisotropically in two dimensions ... more A special statistical model illustrates how an object can move anisotropically in two dimensions by taking advantage of some controlled modifications of its environment, under the condition that the rate of such modifications depends on the position of the object under study.
viXra, 2014
The impact of linear superpositions of magnetic potentials on the physical robustness of “patchin... more The impact of linear superpositions of magnetic potentials on the physical robustness of “patchings” used to build up the “wave section” of an electron orbiting around a magnetic monopole is examined. It is shown that most of these linear superpositions must be discarded if one wishes to preserve the possibility that magnetic monopoles may exist.
Physica C: Superconductivity, 1991
Abstract We have measured the Knight shift and the spin-lattice relaxation of the O(2, 3) planar ... more Abstract We have measured the Knight shift and the spin-lattice relaxation of the O(2, 3) planar sites in a single crystal of YBa 2 Cu 3 O 6.5 . We report the anisotropy of these quantities, together with their striking temperature dependences. Our data are not easy to understand in any theoretical model presently available. One approach is to consider the T 1 data to indicate that, for temperatures greater than T c , some electronic fluctuations develop prefertially on the O(2p) orbitals, and not on the Cu(3d) orbitals. However, such an analysis seems incompatible at first sight with our Knight shift data, because the planar oxygen Knight shift tensor appears to result from a single electronic susceptibility and not two different susceptibilities. We, however, propose an alternative “two-fluid” model analysis which may account qualitatively for the NMR features observed. The originality of our experimental work, if compared with some other, lies to a large extent in our ability to take advantage of the possibilities offered by a 17 O-enriched single crystal study.
Physica C: Superconductivity, 1990
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Thesis Chapters by François Barriquand
Papers by François Barriquand