Communication through quantum-controlled noise

In a recent series of works [Ebler et al. Phys. Rev. Lett. 120, 120502 (2018); arXiv:1809.06655v2; arXiv:1810.10457v2], it has been proposed that the quantum superposition of causal order -- the quantum switch -- may offer an enhancement of classical and quantum channel capacity through noisy channels, a phenomena that was coined `causal activation'. In this paper we attempt to clarify the nature of the purported advantage, by comparing the quantum switch to a class of processes that can be interpreted as quantum superposition of processes with the same causal order. We show that some of these processes can match or even outperform the quantum switch at enhancing classical and quantum channel capacity, and argue that they require the same resources as the switch. We conclude, in agreement with Abbott et al. [arXiv:1810.09826v1], that the aforementioned advantages appear to be attributable to the ability to coherently control quantum operations, and not to indefinite causal order per se.Comment: 8 pages, 1 figure. Published versio

Friction properties of fluorinated carbons

In boundary lubrication regime, friction reduction and antiwear processes are associated to the presence of additives in the lubricating oils or greases. These processes are due to the formation of protective tribofilms resulting from chemical reactions between the additives and the sliding surfaces, in the physico-chemical conditions of the sliding contact. Conventional antiwear additives mainly consist of transition metal organo phosphate or thiophosphates which present a remarkable efficiency in the case of contacts between ferrous alloys. In the case of non reacting surfaces, these additives become inactive. Recently developped lubrication strategies consist in the use of dispersion in oils of nano additives able to build the protective tribofilm in the sliding contact without reaction with the surfaces. Carbon fluorinated phases, due to their lamellar structure and their high chemical stability even at relatively high temperature (400°C) represent interesting candidates as lubricant nano-additives subjected to present friction reduction, anti wear and anti corrosion actions. This work presents the tribologic behaviour of some carbon fluorinated derivatives such as graphite fluorides, fluorinated carbon nanofibers, fluorinated carbon nanodiscs and fluorinated carbon blacks. The influence, on the tribologic performances, of the structure of the initial carbon phases, of the fluorination rate (0<F/C<1) and the structure of the fluorinated compounds is discussed

Sur la vergogna dans le Décaméron

After describing and illustrating by reference to Dante’s Convivio the main lines of the context in which the question of passions in Boccaccio’s Decameron can be understood, the study focuses on one passion in particular : “vergogna”. “Vergogna” is in fact composed of affects that cannot be reduced to one another. The study analyses one of them that appears to play a regulatory function, not only in the mimesis of the “human comedy” as respresented by the different narrators, but also metatextually, in terms of the strategy the author deploys. This strategy not only provides the text –taken as a unitarian whole– with an efficient principle of internal cohesion ; it also calls into play quite specific options as regards “practical” philosophy.Après avoir tracé dans ses grandes lignes le cadre général – illustré notamment par le Convivio de Dante – où s’inscrit la question des passions dans le Décaméron de Boccace, l’étude s’attache à préciser les enjeux d’une passion particulière, la « vergogna ». Elle montre que celle-ci se décompose en réalité en affects non exactement réductibles l’un à l’autre. Elle se conclut par l’examen de l’un d’eux, qui a une fonction régulatrice, non seulement dans la mimèsis de la « comédie humaine » telle que la représentent les différents narrateurs, mais, sur le plan métatextuel, dans la stratégie d’auteur mise en œuvre, celle-là même qui non seulement fournit au texte pris dans sa globalité de recueil unitaire un principe efficace de cohésion interne, mais met en jeu des options bien précises en matière de philosophie « pratique »

De l’image au texte et du texte à l’image : sur les puissances de la peinture chez Boccace

C’est une idée de peintre, ou de quelqu’un qui a vu de la peinture ; pas forcément le tableau. Mais allons plus loin. Ce ne sont pas des descriptions. C’est une interprétation de… ; une herméneutique de… – C’est-à-dire, demanda l’Autre ? – C’est-à-dire que l’interprétation établit une distance qui rend vraisemblable (et je n’ai pas dit vraie) la présence du tableau désigné par le geste. « Regarde la peinture ». Il faut cette fiction de la réalité, qui est au sophiste comme le fond du tableau ..