Dissertationen zum Thema „États de graphes“
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Durbec, Amélia. „Dynamiques causales de graphes réversibles et quantiques“. Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0459.
Der volle Inhalt der QuelleCausal graph dynamics are a twofold extension of cellular automata: the underlying grid is extended to an arbitrary graph of bounded degree and the graph itself can evolve in time.In the reversible regime, we prove that causal graph dynamics can be reversible while creating/destroying vertices, through three different models that we prove to be equivalent.Based on these results, we exhibit causal dynamics that are both reversible and increasing in space, which brings new insights into the compatibility between the time arrow and reversibility. We define a notion of graph subshifts, which can be used to study causal dynamics of graphs by unifying temporal and spatial dimensions, in the same way that 1D cellular automata can be studied with 2D subshifts of finite type.In the quantum regime, our first contribution is to provide a rigorous definition of state space. A notable question was whether vertex names are necessary; we prove they are indeed necessary in order to prevent faster-than-light signaling. We also point out that renaming on graphs is the natively discrete analog of coordinate changes
Holderbaum, William. „Commande des systèmes à entrées booléennes“. Lille 1, 1999. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1999/50376-1999-123.pdf.
Der volle Inhalt der QuelleShettell, Nathan. „Quantum Information Techniques for Quantum Metrology“. Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS504.
Der volle Inhalt der QuelleQuantum metrology is an auspicious discipline of quantum information which is currently witnessing a surge of experimental breakthroughs and theoretical developments. The main goal of quantum metrology is to estimate unknown parameters as accurately as possible. By using quantum resources as probes, it is possible to attain a measurement precision that would be otherwise impossible using the best classical strategies. For example, with respect to the task of phase estimation, the maximum precision (the Heisenberg limit) is a quadratic gain in precision with respect to the best classical strategies. Of course, quantum metrology is not the sole quantum technology currently undergoing advances. The theme of this thesis is exploring how quantum metrology can be enhanced with other quantum techniques when appropriate, namely: graph states, error correction and cryptography. Graph states are an incredibly useful and versatile resource in quantum information. We aid in determining the full extent of the applicability of graph states by quantifying their practicality for the quantum metrology task of phase estimation. In particular, the utility of a graph state can be characterised in terms of the shape of the corresponding graph. From this, we devise a method to transform any graph state into a larger graph state (named a bundled graph state) which approximately saturates the Heisenberg limit. Additionally, we show that graph states are a robust resource against the effects of noise, namely dephasing and a small number of erasures, and that the quantum Cramér-Rao bound can be saturated with a simple measurement strategy. Noise is one of the biggest obstacles for quantum metrology that limits its achievable precision and sensitivity. It has been showed that if the environmental noise is distinguishable from the dynamics of the quantum metrology task, then frequent applications of error correction can be used to combat the effects of noise. In practise however, the required frequency of error correction to maintain Heisenberg-like precision is unobtainable for current quantum technologies. We explore the limitations of error correction enhanced quantum metrology by taking into consideration technological constraints and impediments, from which, we establish the regime in which the Heisenberg limit can be maintained in the presence of noise. Fully implementing a quantum metrology problem is technologically demanding: entangled quantum states must be generated and measured with high fidelity. One solution, in the instance where one lacks all of the necessary quantum hardware, is to delegate a task to a third party. In doing so, several security issues naturally arise because of the possibility of interference of a malicious adversary. We address these issues by developing the notion of a cryptographic framework for quantum metrology. We show that the precision of the quantum metrology problem can be directly related to the soundness of an employed cryptographic protocol. Additionally, we develop cryptographic protocols for a variety of cryptographically motivated settings, namely: quantum metrology over an unsecured quantum channel and quantum metrology with a task delegated to an untrusted party. Quantum sensing networks have been gaining interest in the quantum metrology community over the past few years. They are a natural choice for spatially distributed problems and multiparameter problems. The three proposed techniques, graph states, error correction and cryptography, are a natural fit to be immersed in quantum sensing network. Graph states are an well-known candidate for the description of a quantum network, error correction can be used to mitigate the effects of a noisy quantum channel, and the cryptographic framework of quantum metrology can be used to add a sense of security. Combining these works formally is a future perspective
Cohen, Ruben Y. „Thermalization of a 1-dimensional Rydberg gas and entanglement distribution across quantum networks“. Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS281/document.
Der volle Inhalt der QuelleThe collective behavior of Rydberg gases is at the heart of many proposals for quantum information. This thesis treats two distinct topics: the collective dynamic of a Rydberg ensemble and the use of quantum repeaters across quantum networks.In the first part of this thesis, we choose to focus on a simple system involving Rydberg atoms: a 1-dimensional Rydberg gas coupled to a laser resonant with the Rydberg transition. Rydberg atoms interact together through the dipole-dipole interaction. This particular feature is used for quantum information purposes, like applying multi-qubits gates for example. This interaction is strong enough so that the dynamic of such system in the regime of few excitations in the gas ensemble is already intractable without any assumptions. One of them is the hardcore Rydberg sphere assumption: we approximate this interaction by a sphere around each excitation inhibiting any second excitation within it. Another one is to suppose that the system thermalizes in such regime; a statistical treatment could then be applied. We have investigated the thermalization of a 1D-Rydberg gas and evaluated the accuracy of the microcanonical ensemble predictions under the first assumption. To do so, we have numerically simulated the dynamic of such system constituted by 100 atoms, in the regime of at most two excitations in the chain, in the initial excitation-less state. Furthermore, we constructed a 6-dimensional analytical model. Comparing the three approaches together, we have concluded that the numerical simulation and the analytical model both agree together but contradicts the microcanonical treatment. In this regime, the microcanonical ensemble is unadapted.In the second part of this thesis, we have studied the distribution of entanglement across a generic quantum network. We have mapped these quantum networks to undirected graphs and studied two different routing scenarios:- the classical routing of quantum entanglement corresponding to the scenario where clients of the network can perform only a single Bell measurement or keep a single qubit. This is the usual model of quantum repeaters. On these networks, peer-to-peer communication problems are equivalent to the vertex disjoint path problem. When the peers are chosen by an adversary, we have found two limitations due to the topological genus and the minimum degree of the graph. We have found two network architectures (almost) saturating the most constraining one, the minimum degree inequality. For the case where the peers are chosen at random, we have studied a specific graph lying in a 2- or 3-dimensional manifold and investigated the trade-off between the quantum links and the number of peers that can communicate simultaneously through the network.- true quantum routing problem (using network coding) corresponding to the situation where the quantum network is composed by small quantum processors that could apply local gates. We focus on a particular communication problem, namely the butterfly network, where classical routing is impossible. Using network coding, this communication is solved
Morsellino, Thomas. „Présentation et étude de quelques problèmes d’algorithmique distribuée“. Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14586/document.
Der volle Inhalt der QuelleIn this thesis, we first present a study of several problems in the field of distributed algorithms. We provide a formal model that relies on anonymous networks. In this model, we characterize graphs in which it is possible to solve enumeration and leader election problems. This characterization is based on graph homomorphism. We introduce two algorithms with polynomial complexities that improve existing works with exponential complexities. On the other hand, we study the snapshot problem and we introduce the notion of weak snapshot. We show that there exist solutions for this problem in the context of anonymous networks. We present several results about distributed snapshots that deal with checkpoint and rollback recovery, termination detection or the cartography computation of a network. In a practical aspect, we present the conception, the development process and the implementation of these distributed snapshot algorithms within the simulation and visualization software ViSiDiA
Alsayeg, Khaled. „Synthèse de contrôleurs séquentiels QDI faible consommation prouvés corrects“. Grenoble INPG, 2010. http://www.theses.fr/2010INPG0076.
Der volle Inhalt der QuelleThe study of asynchronous circuits is an area where much research has been conducted in recent years. Asynchronous circuits have shown several interesting features like robustness, scalability, low consumption or low electromagnetic radiation. Among the different classes of asynchronous circuits, Quasi Delay Insensitive circuits (QDI) showed very interesting characteristics in terms of low power consumption and robustness to variations of PVT (Process, Voltage, and Temperature). The use of these circuits is particularly well suited for applications operating in a critical environment and for which consumption is paramount. In this framework, the work of this thesis aims the low power consumption design and synthesis of asynchronous state machines (QDI). A method for synthesizing low-consumption asynchronous sequential controllers has been developed. The method relies on an adequate modeling of controllers and a direct mapping synthesis technique using specific components called sequencers. This technique is suitable for synthesizing large controllers. The circuits obtained are formally verified to ensure their properties in terms of robustness and are proved functionally correct. Thereby, a formal verification method has been implemented to validate the sequential controllers on the one hand, and more generally, any other asynchronous circuit. This technique uses a hierarchical model of asynchronous circuits in PSL and a formal verification tool called RAT
Valdès, Gomez Hector. „Relations entre états de croissance de la vigne et maladies cryptogamiques sous différentes modalités d’entretien du sol en région méditerranéenne“. Montpellier, ENSA, 2007. http://www.theses.fr/2007ENSA0012.
Der volle Inhalt der QuelleLe, Corre Gaëlle. „Variations non standard dans les écrits épistolaires de soldats de l'armée confédérée de l'état de Virginie“. Thesis, Brest, 2015. http://www.theses.fr/2015BRES0063.
Der volle Inhalt der QuelleThroughout the Civil War (1861-1865), thousands of low ranking soldiers on both sides of the conflict took up their pens to inquire after their families and give news from the front. Usually semiliterate, most of these soldiers were far from mastering written conventions. The 170,000-word corpus, on which this thesis is based, is composed of 366 letters written by 80 privates, corporals and sergeants from Virginia. Their idiosyncratic and ingenuous spellings as well as their use of non-standard morphosyntactic variations offer a great opportunity to gain further insight into the vernacular spoken by white lower-class people in Virginia around the middle of the 19th century.According to Guy Bailey (1997), certain specificities of the Southern American Vernacular English (SAVE) appeared after the Civil War, as a reaction against Northern domination and the humiliation caused by the defeat. The non standard variations found in the Virginia Civil War Corpus tend to question this hypothesis and reveal that most of the features, that are today associated with SAVE, were already present in low ranking soldiers' writings.Despite the phonetic spelling and the use of non-standard grammatical and lexical forms, the letters reveal that the soldiers were fully aware that their vernacular speech was not in line with academic conventions. We thus observe a constant tension between the academic prescriptive norm and non-standard variations. We may wonder if this constant oscillation is only triggered by an internal conflict between different linguistic models or if, on the contrary, the presence of these dialectal variations must be understood as signs of specific enunciative operations
Jelassi, Haikel. „Spectroscopie photoassociative des états moléculaires faiblement liés du rubidium : Analyse par la méthode de Lu-Fano.Étude de la réalisation d'une lentille à atomes“. Phd thesis, Université Paris Sud - Paris XI, 2007. http://tel.archives-ouvertes.fr/tel-00189099.
Der volle Inhalt der QuelleMorsellino, Thomas. „Présentation et étude de quelques problèmes d'algorithmique distribuée“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00991004.
Der volle Inhalt der QuelleDelot, Sébastien. „Les galeries d’art contemporain à New York, 1941‐1993 : topographie et marché de l’art“. Rennes 2, 2011. http://www.theses.fr/2011REN20014.
Der volle Inhalt der QuelleIn 1941, the majority of the exiled European avant-garde settled in New York and influenced the New York art scene. During this very same period, the future heavyweights of the art market emerged. In the 1960s, the Castelli Gallery was a dominant force in the art market, which was becoming increasingly internationalized through a network of alliances in the US and Europe. But to fully understand the Castelli Gallery’s influence, an examination of its relations with the Ileana Sonnabend Gallery in Paris is necessary. By analyzing the extensive, regular, and - notably – unpublished correspondence between the two, a better understanding can be gained of the preeminent role played by the Sonnabend Gallery in promoting American artists in Europe in the 1960s. The aim of this thesis is to etablish a history of contemporary art galleries in New York by assessing the role they played in the major topographical, commercial, and esthetic shifts from 1941 to 1993
Martin, Côme. „Le roman visuel : relations entre texte et image dans la bande dessinée et le roman américains contemporains“. Thesis, Paris 4, 2013. http://www.theses.fr/2013PA040089.
Der volle Inhalt der QuelleThe aim of this PhD research is to study the relationship between text and image in contemporary American literature; in other words, to analyze the in-between represented by the visual novel, a genre introduced by Thierry Smolderen in 2006.My main corpus is made of two novels, Mark Z. Danielewski’s House of Leaves (2000) and Jonathan Safran Foer’s Extremely Loud & Incredibly Close (2005), and two comic books, Chris Ware’s Jimmy Corrigan: The Smartest Kid on Earth (2000) and Alison Bechdel’s Fun Home (2006). I start by assuming that those two genres, in spite of their distinctive characteristics, share similarities in their narrative techniques, and therefore suggest an analysis in three parts. First, I shall study the visual devices used by the above books, focusing in particular on the instances where the text becomes visual, and the image takes on narrative qualities. Then, a second part will concentrate on the way those devices emphasis the space of the page, and how they modify the narration by questioning its temporal and spatial conventions. Finally, I will analyze the book, as a motif and as an object in the corpus. The visual novel is not only a new way to approach the text/image relationship in literature; it also allows us to imagine new forms that go beyond the current standards, of which the books studied here are the first examples
Bourgeon, Marie-Aure. „Conception et évaluation d'un dispositif d'imagerie multispectrale de proxidétection embarqué pour caractériser le feuillage de la vigne“. Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS066/document.
Der volle Inhalt der QuelleMutispectral imaging systems are widely used in remote sensing for Precision Viticulture. In this work, this technique was applied in the proximal sensing context to characterize vine foliage. A mobile terrestrial experimental system is presented, composed of a GPS receiver, a multi-spectral camera acquiring visible and near infrared images, and a Greenseeker RT-100 which measures the Normalized Difference Vegetative Index (NDVI). This optical system observes vine foliage in the trellis plan, in natural sunlight. The experimental field is planted with Chardonnay, Pinot Noir and Meunier cultivars in a latin squared pattern. In 2013, six datasets were acquired at various phenological stages.Spectral properties of the vegetation are accessible on images when they are calibrated in reflectance. This step requires the use of a MacBeth colorchart as a radiometric reference. When the chart is hidden by leaves, the calibration parameters are estimated by simple linear interpolation using the results from resembling images, which have a visible chart. The performance of this method is verified with a cross-validation technique (LOOCV).To validate the data provided by the experimental system, the NDVI given by the Greenseeker was compared to those computed from the calibrated images. The assessment of the versatility of the system is done with the images where several indices were determined. It allows an innovative follow-up of the vegetative growth, and offering phenotyping applications. Moreover, the characterization of the sanitary state of the foliage prove that this technique is versatile and accurate
Soulé, Paul. „Étude des Bords des Phases de l’Effet Hall Quantique Fractionnaire dans la Géométrie d’un Contact Ponctuel Quantique“. Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112215/document.
Der volle Inhalt der QuelleI present in this thesis a study that I did in the university Paris-sud under the supervision of Thierry Jolicœur onto Fractional Quantum Hall (FQH) phases in the cylinder geometry. After a short introduction in the first chapter, I present some basic concept relative to the FQH effect in the second one and introduce some essential features relative to the cylinder geometry, useful for the chapters 3, 4, and 5. The chapter 3 is dedicated to the study of the thin cylinder limit, i.e. when the circumference of the cylinder is of the order of a few magnetic length. In this limit, it is known that the Laughlin wave function at the filling factor 1/q is reduced to a one dimensional crystal in the lowest Landau level orbitals where one every q orbitals is occupied. We Taylor expand the Hamiltonian when the circumference is small compare to the magnetic length in order to study an intermediate limit. When only the first four terms of the development are kept, it is possible to find exact representations of the ground state with "squeezing" operators or matrix products. We also find similar representations for quasiholes, quasielectrons and the magnetorton branch. These results have been published in the article Phys. Rev. B 85, 155116 (2012). In the chapter 4 and 5 I focus onto the gapless chiral edge excitations of FQH phases. I present a microscopic study of those edges states in the cylindrical geometry where quasiparticles are able to tunnel between edges. I first study the principal FQH phase at the filling fraction 1/3 whose ground state is well described by the Laughlin wave function in the chapter 4. For an energy scale lower than the bulk gap, the effective theory is given by a very peculiar one dimensional electron fluid localized at the edge: a chiral Luttinger liquid. Using numerical exact diagonalizations, we study the spectrum of edge modes formed by the two counter-propagating edges on each side of the cylinder. We show that the two edges combine to form a non-chiral Luttinger liquid, where the current term reflects the transfer of quasiparticles between edges. This allows us to estimate numerically the Luttinger parameter for a small number of particles and find it coherent with the one predicted by X. G. Wen theory. We published this work in Phys. Rev. B 86, 115214 (2012). I then analyze edge modes of the FQH phase at filling fraction 5/2 in the chapter 5. From a Conformal Field Theory (CFT) based construction, Moore and Read (Nucl. Phys. B, 1991) proposed that the essential physics of this phase is described by a paired state of composite fermions. A striking property of this state is that emergent excitations braid with non-Abelian statistics. When localized along the edge, those excitations are described through a chiral boson and a Majorana fermion. In the cylinder geometry, we show that the spectrum of edge excitations is composed of all conformal towers of the IsingxU(1) model. In addition, with a Monte Carlo method, we estimate the various scaling dimensions for large systems (about 50 electrons), and find them consistent with the CFT predictions.In the last chapter of my manuscript, I present a work that I did in UBC (Vancouver) in collaboration with Marcel Franz onto quantum spin Hall phases in graphene induced by adatoms. In this system, adatoms induce a spin orbit coupling for electrons in the graphene sheet and create some disorder which might be responsible for destruction the spectral gap. We show in this chapter and in the article [Phys. Rev. B 89, 201410(R) (2014)] that the spectral gap remains open for a realistic range of parameters. In addition, with analytical computations in the low energy approximation and numerical exact diagonalizations, we find characteristic signal in the local density of states highlighting the presence of topological gap. This signal might be observed in scanning tunneling spectroscopy experiments
Licari-Guillaume, Isabelle. „« Vertigo's British Invasion » : la revitalisation par les scénaristes britanniques des comic books grand public aux Etats-Unis (1983-2013)“. Thesis, Bordeaux 3, 2017. http://www.theses.fr/2017BOR30044/document.
Der volle Inhalt der QuelleThis thesis deals with the editorial and aesthetic history of the Vertigo imprint, which was created in 1993 by DC Comics, a US-American comics publisher. I shall consider in particular the contribution of British scriptwriters employed by DC and then by Vertigo from the 1980s onwards. Theise creators played a tremendous role, both at the time of Vertigo's founding by editor Karen Berger and at a later date, as the imprint gathered widespread recognition. The genesis of the Vertigo imprint sheds light on the so-called “British Invasion”, that is to say the appearance within the American industry of several UK-based creators working for DC Comics. Spearheaded by Alan Moore, the “invasion” brought to the fore many of the most important scriptwriters of years to come, such as Grant Morrison and Neil Gaiman, whose Sandman series has been described as a major landmark in the recognition of the medium. Existing criticism regarding Vertigo tends to focus on the body of work produced by British authors, without necessarily discussing their national specificity. My goal is therefore double; on the one hand, I intend to write a history of the label as the producer of a specific media culture that belongs to a given socio-historical context and is grounded in the practices and representations of the field's actors (producers and consumers in a broad sense). On the other hand, the awareness of the context in which the books are produced shall allow me to interrogate the imprint's poetics, thus identifying the specificity of a “British school of writing” within the comics mainstream industry
Böhm, Julian. „Phénomènes de transport originaux dans des expériences micro-ondes via la mise en forme spatiale et spectrale“. Thesis, Université Côte d'Azur (ComUE), 2016. http://www.theses.fr/2016AZUR4048/document.
Der volle Inhalt der QuelleTransport of waves plays an important role in modern communication systems like Wi-Fi or optical fibres. Typical problems in such systems concern security against possible intruders, energy consumption, time efficiency and the possibility of mode filtering. Microwave experiments are suited to study this kind of problems, because they offer a good control of the experimental parameters. Thus we can implement the method of wave shaping to investigate atypical transport phenomena, which address the mentioned problems. Wave front shaping solely based on the transmission together with the Wigner-Smith time delay formalism allows me to establish special scattering states in situ. These scattering states avoid a pre-selected region, focus on a specific spot or follow trajectories of classical particles, so called particle-like scattering states. Mode filtering is induced inside a waveguide with wavy boundaries and position dependent loss. The boundary profiles are chosen in such a way that the two propagating modes describe an encircling of an exceptional point in the Bloch picture. The asymmetric mode filtering is found due to the appearing non-adiabatic transitions. Another part of my work deals with Grover’s quantum search. I put such a search into practice in a two-dimensional graphene-lattice using coupled resonators, which form a tight-binding analogue. In this proof of principle experiment we search for different resonators attached to the graphene-lattice. Furthermore, the scaling behaviour of the quantum search is quantified for a linear chain of resonators
Alsayeg, K. „Synthèse de contrôleurs séquentiels QDI faible consommation prouvés corrects“. Phd thesis, 2010. http://tel.archives-ouvertes.fr/tel-00540981.
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