Дисертації з теми "Applications du calcul quantique"
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Kempe, Julia. "Calcul quantique : marches aléatoires et enchevêtrement, applications cryptographiques." Paris, ENST, 2001. http://www.theses.fr/2001ENST0015.
Повний текст джерелаKempe, Julia. "Calcul quantique : marches aléatoires et enchevêtrement, applications cryptographiques /." Paris : École nationale supérieure des télécommunications, 2001. http://catalogue.bnf.fr/ark:/12148/cb388211970.
Повний текст джерелаGrospellier, Antoine. "Décodage des codes expanseurs quantiques et application au calcul quantique tolérant aux fautes." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS575.
Повний текст джерелаFault tolerant quantum computation is a technique to perform reliable quantum computation using noisy components. In this context, quantum error correcting codes are used to keep the amount of errors under a sustainable threshold. One of the main problems of this field is to determine the minimum cost, in terms of memory and time, which is needed in order to transform an ideal quantum computation into a fault-tolerant one. In this PhD thesis, we show that the family of quantum expander codes and the small-set-flip decoder can be used in the construction of ref. [arXiv:1310.2984] to produce a fault-tolerant quantum circuit with constant space overhead. The error correcting code family and the decoder that we study has been introduced in ref. [arXiv:1504.00822] where an adversarial error model was examined. Based on the results of this article, we analyze quantum expander codes subjected to a stochastic error model which is relevant for fault-tolerant quantum computation [arXiv:1711.08351], [arXiv:1808.03821]. In addition, we show that the decoding algorithm can be parallelized to run in constant time. This is very relevant to prevent errors from accumulating while the decoding algorithm is running. Beyond the theoretical results described above, we perform a numerical analysis of quantum expander codes to measure their performance in practice [arXiv:1810.03681]. The error model used during these simulations generates X and Z type errors on the qubits with an independent and identically distributed probability distribution. Our results are promising because they reveal that these constant rate codes have a decent threshold and good finite length performance
Bredariol, Grilo Alex. "Quantum proofs, the local Hamiltonian problem and applications." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC051/document.
Повний текст джерелаIn QMA, the quantum generalization of the complexity class NP, a quantum state is provided as a proof of a mathematical statement, and this quantum proof can be verified by a quantum algorithm. This complexity class has a very natural complete problem, the Local Hamiltonian problem. Inspired by Condensed Matters Physics, this problem concerns the groundstate energy of quantum systems. In this thesis, we study some problems related to QMA and to the Local Hamiltonian problem. First, we study the difference of power when classical or quantum proofs are provided to quantum verification algorithms. We propose an intermediate setting where the proof is a “simpler” quantum state, and we manage to prove that these simpler states are enough to solve all problems in QMA. From this result, we are able to present a new QMA-complete problem and we also study the one-sided error version of our new complexity class. Secondly, we propose the first relativistic verifiable delegation scheme for quantum computation. In this setting, a classical client delegates her quantumcomputation to two entangled servers who are allowed to communicate, but respecting the assumption that information cannot be propagated faster than speed of light. This protocol is achieved through a one-round two-prover game for the Local Hamiltonian problem where provers only need polynomial time quantum computation and access to copies of the groundstate of the Hamiltonian. Finally, we study the quantumPCP conjecture, which asks if all problems in QMA accept aproof systemwhere only a fewqubits of the proof are checked. Our result consists in proposing an extension of QPCP proof systems where the verifier is also provided an auxiliary classical proof. Based on this proof system, we propose a weaker version of QPCP conjecture. We then show that this new conjecture can be formulated as a Local Hamiltonian problem and also as a problem involving the maximum acceptance probability of multi-prover games. This is the first equivalence of a multi-prover game and some QPCP statement
Duchemin, Ivan. "Calcul quantique Hamiltonien : théorie et application aux portes logiques mono-moléculaires." Toulouse 3, 2006. http://www.theses.fr/2006TOU30243.
Повний текст джерелаRibeiro, Pedro. "Transitions de Phase Quantiques dans des Modèles de Spin Collectif. Applications au Calcul Adiabatique." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00812554.
Повний текст джерелаLemaire, Alexis. "Application de l'hypercalculie et de l'informatique quantique gravifique à l'intelligence artificielle générale." Reims, 2010. http://www.theses.fr/2010REIMS020.
Повний текст джерелаFathallah, Mohamed. "Calcul et localisation de l'énergie d'une molécule : programmation informatique et applications en mécanique moléculaire, et essai de décomposition atomique en mécanique quantique." Aix-Marseille 3, 1991. http://www.theses.fr/1991AIX30025.
Повний текст джерелаBettonte, Gabriella. "Quantum approaches for Worst-Case Execution-Times analysis of programs." Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASG026.
Повний текст джерелаQuantum computing is gaining popularity in the computer science community. The awareness of the potential of quantum computing started in 1981, when Richard Feynman first speculated about building a quantum computer. However, until recently, the field has known much skepticism about its long-term practical capabilities to solve problems. In particular, researchers are still facing the challenge of building scalable and reliable quantum computers. Lately, many companies have obtained encouraging results and built quantum machines with enough qubits to start conducting interesting experiments. We chose the worst-case execution-time (WCET) evaluation as the application of our research on quantum computing, as it is crucial for various real-time applications. WCET analysis guarantees that a program's execution time matches all the scheduling and timing constraints. In quantum algorithms history, attention was often given to problems with a particular mathematical structure. The WCETs evaluation, as an opposite, is not a particularly quantum-friendly problem, and it has already proven efficient classical solutions. Hence, it is worth exploring the impact of quantum computing on those kinds of problems, with the spirit of finding new and concrete fields to which quantum computing could bring its potential. If not, research on such specific fields will help to set the boundaries of which applications could benefit from quantum computing. This thesis presents different quantum approaches to perform WCETs evaluations of programs under simplified assumptions
Hubert, Mickaël. "Relativistic coupled cluster theory for excited states at a general excitation rank : applications to diatomic molecules." Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2046/.
Повний текст джерелаThis thesis focuses on methodological developments of the theoretical evaluation of the quantum and relativistic energy of electronically excited states of an atom or a molecule. The wave-function method Coupled Cluster (CC) is currently one of the most accurate methods to calculate these states for many-body systems. The implementation presented is based on the many-body relativistic 4-component Dirac-Coulomb Hamiltonian and a Coupled Cluster wave function at arbitrary excitation rank. The excited states are evaluated using linear response theory by diagonalizing the Coupled Cluster Jacobian matrix. The work focuses on the evaluation of these second-quantized elements using a new commutator-based algorithm, and on its adaptation to a Dirac 4-component relativistic formalism. Finally, I present some applications of the code to challenging diatomic molecules
Vranckx, Stéphane. "Dynamical study of diatomics : applications to astrochemistry, quantum control and quantum computing." Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209261.
Повний текст джерела1) HeH+, a species of great astrochemical importance which is thought to be the first molecular species to have formed in the universe;
2) CO2+, a metastable dication of particular interest in quantum control experiments due to its long-lived lowest vibrational level;
3) 41K87Rb, a polar molecule that can be formed at very low temperature and trapped, making it a good candidate for quantum computing schemes.
First, we use ab initio methods to compute accurate potential energy curves for the lowest singlet and triplet states of HeH+ as well as the potential energy curves, transition dipole moments and nonadiabatic radial couplings of the ground 3Π state of CO2+ and of its 11 lowest 3Σ- states.
In a second step, we use this ab initio data to compute the photodissociation and radiative association cross sections for the a and b 3Σ+ states of HeH+, as well as the values of the corresponding rate constants for astrophysical environments. The photodissociation cross sections from the lowest vibrational level of CO2+ is also determined.
Going one step further, we optimize laser control fields that drive the photodissociation dynamics of HeH+ and CO2+ towards specific channels. We compare two field optimization methods: a Møller operator-based Local Control approach and Optimal Control Theory. In both cases, we add a constraint that minimizes the area of the optimized fields.
Finally, we focus on one of the potential applications of high-fidelity laser control: the use of small molecular systems as quantum computers. We more specifically study the potential implementation of both intra- and intermolecular logic gates on data encoded in hyperfine states of trapped ultracold polar 41K87Rb molecules, opening interesting perspectives in terms of extensibility.
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Dans cette thèse, nous étudions théoriquement les propriétés de molécules diatomiques, leur dynamique de réaction ainsi que le contrôle de cette dynamique à l'aide de champs laser. Notre travail porte plus spécifiquement sur trois espèces :
1) HeH+, un composé-clé en astrochimie considéré comme la première espèce moléculaire qui s'est formée dans l'univers ;
2) CO2+, un dication métastable qui se prête bien à des expériences de contrôle quantique en raison du relativement long temps de vie de son état vibrationnel le plus bas ;
3) 41K87Rb, une molécule polaire qui présente la particularité de pouvoir être formée à très basse température et piégée, ce qui en fait un bon support physique potentiel pour la réalisation d'un ordinateur quantique moléculaire.
Nous utilisons tout d'abord des méthodes de calcul ab initio afin d'obtenir les courbes d'énergie potentielle des premiers états singulets et triplets de HeH+ avec un haut de degré de précision, ainsi que les courbes d'énergie potentielle, les moments dipolaires de transition et les couplages non-adiabatiques radiaux de l'état fondamental 3Π de CO2+ et de ses 11 premiers états 3Σ-.
Ensuite, nous utilisons ces données ab initio pour calculer les sections efficaces de photodissociation et d'association radiative des états a et b 3Σ+ de HeH+, ainsi que les constantes cinétiques associées à ces processus dans les conditions rencontrées dans des environnements astrophysiques. Les sections efficaces de photodissociation du niveau vibrationnel le plus bas de CO2+ sont également calculées.
Nous allons ensuite un cran plus loin en optimisant des champs laser qui guident la dynamique de photodissociation de HeH+ et CO2+ vers des canaux de dissociation spécifiques. Nous comparons deux méthodes d'optimisation de ces champs: une approche de contrôle local basée sur les opérateurs de Møller et la théorie du contrôle optimal. Dans le deux cas, nous incluons une contrainte qui minimise l'aire des champs.
Enfin, nous nous concentrons sur l'une des applications possibles du contrôle laser à haute fidélité :l'utilisation de petits systèmes moléculaires comme ordinateurs quantiques. Nous étudions plus spécifiquement l'implémentation possible d'opérations logiques intra- et intermoléculaires sur des données encodées dans des états hyperfins de molécules de 41K87Rb piégées, ce qui ouvre des perspectives intéressantes en terme d'extensibilité.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Mahmoudi, Farvah. "Chromodynamique quantique aux collisionneurs hadroniques : vers une automatisation du calcul des processus multi-particules à l'ordre d'une boucle : application à la production de deux photons et un jet." Chambéry, 2004. http://www.theses.fr/2004CHAMS013.
Повний текст джерелаThe future CERN collider (LHC) bas a fantastic potential of discovery, provided QCD can be quantitatively predicted. To do so, it is necessary to work at NLO approximation in order to reduce the dependence of the cross-section on the non-physical scales. To obtain results in this approximation, one has to calculate the cross-sections of the partonic subprocesses contributing to the studied reaction at the lowest order, and also the virtual corrections (loop corrections) and the real corrections. The calculation of the virtual corrections remains very complicated if the number of external particles is greater than four or if the external (internal) particles are massive. Ln this thesis, an automatic method which enables to calculate one loop diagrams with five external legs and which can be generalized to the case of massive particles is presented. Ln a first part, we describe different tools and methods necessary to such calculations. We then apply them to the calculation of the (gluon + gluon -> photon + photon + gluon) reaction, which interests the ATLAS and CMS experimentalists as the background for the Higgs boson search. We also give the explicit result for this amplitude for each helicity configuration in a compact form and a clearly gauge invariant representation. We finally present a phenomenological study of this reaction
Zvereva-Loëte, Natalia. "Applications de la Chimie Quantique à la Spectroscopie : Molécules, Complexes de Van der Waals, Molécules piégées." Habilitation à diriger des recherches, Université de Bourgogne, 2009. http://tel.archives-ouvertes.fr/tel-00452878.
Повний текст джерелаMançois, Fabien. "Nouveaux composés photochimiques dédiés aux applications optiques non linéaires." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13930/document.
Повний текст джерелаIn this work we have investigated the commutation of linear and non linear optical properties in organic multifunctional switches. Indolino-oxazolidine compounds and their derivatives were chosen as example of multifunctional systems, because they combine both acidochromic and photochromic properties. The relationships between the molecular structure of these compounds and their optical properties were established by means of high level the quantum chemical approach and hyper-Rayleigh Scattering of light approaches
Bouba, Oumarou. "Théories quantique et semi-classique des intégrales radiales de transitions dipolaires et multipolaires des états excités : Applications au calcul des forces d'oscillateur et des probabilités de transition dans l'approximation à une configuration." Orléans, 1986. http://www.theses.fr/1986ORLE0010.
Повний текст джерелаOumarou, Bouba. "Théories quantique et semi-classique des intégrales radiales de transitions dipolaires et multipolaires des états excités applications au calcul des forces d'oscillateur et des probabilités de transition dans l'approximation à une configuration." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37600169m.
Повний текст джерелаHubert, Mickaël. "Théorie "Coupled Cluster" relativiste pour les états excités au rang d'excitation général. Applications aux molécules diatomiques." Phd thesis, Université Paul Sabatier - Toulouse III, 2013. http://tel.archives-ouvertes.fr/tel-00844310.
Повний текст джерелаCoine, Clément. "Continuous linear and bilinear Schur multipliers and applications to perturbation theory." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD074/document.
Повний текст джерелаIn the first chapter, we define some tensor products and we identify their dual space. Then, we give some properties of Schatten classes. The end of the chapter is dedicated to the study of Bochner spaces valued in the space of operators that can be factorized by a Hilbert space.The second chapter is dedicated to linear Schur multipliers. We characterize bounded multipliers on B(Lp, Lq) when p is less than q and then apply this result to obtain new inclusion relationships among spaces of multipliers.In the third chapter, we characterize, by means of linear Schur multipliers, continuous bilinear Schur multipliers valued in the space of trace class operators. In the fourth chapter, we give several results concerning multiple operator integrals. In particular, we characterize triple operator integrals mapping valued in trace class operators and then we give a necessary and sufficient condition for a triple operator integral to define a completely bounded map on the Haagerup tensor product of compact operators. Finally, the fifth chapter is dedicated to the resolution of Peller's problems. We first study the connection between multiple operator integrals and perturbation theory for functional calculus of selfadjoint operators and we finish with the construction of counter-examples for those problems
Fremont, Julien. "Etude des contributions aux surfaces de potentiel et couplages non-adiabatiques par calculs ab initio de structures électroniques et mise aux points des Hamiltoniens effectifs pour les prédictions vibrationnelles : applications aux molécules LiH, H+3 et PH3." Reims, 2010. http://theses.univ-reims.fr/sciences/2010REIMS019.pdf.
Повний текст джерелаThis work takes place at the halfway between theoretical chemistry and theoretical molecular spectroscopy by proposing to use at their limits the quantum chemistry methods and then make theoretical predictions on the three molecules LiH, PH3 and H3 +. First of all, a chapter is devoted to quantum chemistry methods used in this work to obtain the potential energy surfaces and electronic states. For applications in molecular spectroscopy, the potential energy surface requires to be very accurate. The second chapter examines the influence of the basis, electronic correlations, relativistic corrections and extrapolation methods on the vibrational levels of LiH molecule. For a molecule with a small number of electrons, it is possible to get such quality on the potential energy surface that the limit the Born-Oppenheimer approximation is reached. The third chapter develops the concepts of contact transformation and effective Hamiltonian. It introduce the terms derived from quantum chemistry calculations needed to finally apply this formalism beyond the Born-Oppenheimer approximation to the LiH molecule. The aim of these two preveiws chapters is to explore the limits of ab-initio methods to characterize the vibrational states of all isotopologues near to the dissociation. The study of molecules with a large number of variables has other types of difficulties. The large number of electrons on one hand makes difficult to quantum chemistry calculations to obtain potential energy surface of good quality, on the other hand, the increase in the number of variables complicates the nuclear wave functions and therefore the calculation of vibrational energy levels. The fourth chapter presents the study within the framework of Born-Oppenheimer of the PH3 molecule containing the derivation of the kinetic energy operator in valence coordinates and calculating the potential energy surface by quantum chemistry method. The molecular symmetries of the Hamiltonian produces effects still poorly understood by scientists. The H3 + molecule in its C3v configuration has a conical intersection where the non-adiabatic effects are revealed. In this final chapter the kinetic energy operator in hyperspherical coordinates and the Jacobian matrix associated with this transformation are derived. The non-adiabatic couplings calculated in Cartesian coordinates are reexpressed hypersheriques. After introducing the adiabatic-diabatic transformation, the geometric phase effects are studied
Wattanakit, Chularat. "Élaboration et application de matériaux poreux : études théoriques et expérimentales." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00912339.
Повний текст джерелаJeandel, Emmanuel. "Techniques algébriques en calcul quantique." Lyon, École normale supérieure (sciences), 2005. http://www.theses.fr/2005ENSL0307.
Повний текст джерелаThe main problem studied is the computation of the Zariski closure of algebraic groups and its applications on quantum computation. We give a polynomial time algorithm to decide whether a finitely generated subgroup of a given reductive group is Zariski-dense. A second algorithm, which computes precisely the Zariski-closure of a finitely generated group is given. These tools gives decidability results for several problems in quantum computing, mainly whether a set of gates is universal. We give also a separation between various models of quantum computing An other part of the thesis deals with finite automata. A new model of automata, topological automata, is defined. We then proved in a unified framework that all models of classical, probabilistic and quantum automata accept only regular languages with an isolated threshold
Dürr, Christoph. "Tomographie discrète, calcul quantique et ordonnancement." Habilitation à diriger des recherches, Université Paris Sud - Paris XI, 2006. http://tel.archives-ouvertes.fr/tel-00111205.
Повний текст джерелаBlais, Alexandre. "Calcul quantique universel sur qubits supraconducteurs." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0031/MQ67692.pdf.
Повний текст джерелаBaboin, Anne-Céline. "Calcul quantique : algèbre et géométrie projective." Phd thesis, Université de Franche-Comté, 2011. http://tel.archives-ouvertes.fr/tel-00600387.
Повний текст джерелаApplencourt, Thomas. "Calcul haute performance & chimie quantique." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30162/document.
Повний текст джерелаThis thesis work has two main objectives: 1. To develop and apply original electronic structure methods for quantum chemistry 2. To implement several computational strategies to achieve efficient large-scale computer simulations. In the first part, both the Configuration Interaction (CI) and the Quantum Monte Carlo (QMC) methods used in this work for calculating quantum properties are presented. We then describe more specifically the selected CI approach (so-called CIPSI approach, Configuration Interaction using a Perturbative Selection done Iteratively) that we used for building trial wavefunctions for QMC simulations. As a first application, we present the QMC calculation of the total non-relativistic energies of transition metal atoms of the 3d series. This work, which has required the implementation of Slater type basis functions in our codes, has led to the best values ever published for these atoms. We then present our original implementation of the pseudo-potentials for QMC and discuss the calculation of atomization energies for a benchmark set of 55 organic molecules. The second part is devoted to the Hight Performance Computing (HPC) aspects. The objective is to make possible and/or facilitate the deployment of very large-scale simulations. From the point of view of the developer it includes: The use of original programming paradigms, single-core optimization process, massively parallel calculations on grids (supercomputer and Cloud), development of collaborative tools , etc - and from the user's point of view: Improved code installation, management of the input/output parameters, GUI, interfacing with other codes, etc
Pomeransky, Andrei. "Intrication et Imperfections dans le Calcul Quantique." Phd thesis, Université Paul Sabatier - Toulouse III, 2004. http://tel.archives-ouvertes.fr/tel-00007256.
Повний текст джерелаDuclos-Cianci, Guillaume. "Outils de calcul quantique tolérant aux fautes." Thèse, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/6770.
Повний текст джерелаPomeransky, Andrei A. "Intrication et imperfections dans le calcul quantique." Toulouse 3, 2004. http://www.theses.fr/2004TOU30132.
Повний текст джерелаQuantum information is a new domain of physics, which studies the applications of quantum systems to the computation and to the information transmission. The quantum computers use the lows of quantum mechanics to perform the calculations much more efficiently than all currently existing computers can. The quantum computers will be influenced by all kinds of perturbations. We study, in the case of two very different quantum computations, the efficiency of the quantum computers in the presence of the static imperfections. One of the fundamental reasons of the extraordinary efficiency of the quantum computers is the effect of quantum entanglement. In the present thesis we study certain important properties of a widely used quantitative measure of entanglement. We consider also the average informational entropy of quantum states, find an explicit expression for this quantity and study some its most important properties
Lalire, Marie. "Développement d'une notation algorithmique pour le calcul quantique." Grenoble INPG, 2006. http://www.theses.fr/2006INPG0113.
Повний текст джерелаNo formalism or language existed ta describe completely and rigorously quantum algorithms and protocols. 5ince these algorithms and protocols have necessarily quantum and classical parts, process algebras seemed a good candidate for such a language. 50, in this thesis, we developed a notation, based on process algebras, which provides a homogeneous style for formai descriptions of concurrent and distributed quantum computations comprising bath quantum and classical parts. Based upon an operational semantics that makes sure that quantum abjects, operations and communications operate according ta the postulates of quantum mechanics, an equivalence has been defined among process states considered as having the same behaviour
Darrigan, Clovis. "Calcul quantique de susceptibilités électriques dans les solides cristallins." Pau, 2001. http://www.theses.fr/2001PAUU3029.
Повний текст джерелаDe, Visme Marc. "Sémantique des Jeux Quantique." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEN056.
Повний текст джерелаIn this thesis, we study quantum programming languages, and focus on the quantum lambda-calculus, a paradigmatic language defined by Selinger and Valiron, which mixes a rich classical control flow (higher order functions, etc.) and quantum data (qubit creation, measure, and unitary operations). In this thesis, we search for a denotational semantics of this language, in other words, we extract the meaning and behaviour of programs by interpreting them in an adequately chosen mathematical universe. In order to model the quantum lambda-calculus, one must adapt the traditional denotational models to the mathematics of quantum computation (Hilbert spaces, density matrices, etc.). We have three main contributions:Firstly, we extend game semantics to the quantum case. Game semantics is a dynamic approach to denotational semantics, which focuses on the sequence of interactions between a program and its environment. We obtain the first denotational model of the full quantum lambda-calculus which is both compositional and interactive, meaning that it represents the dynamic of the execution. Our model generalise the recently developed model for the probabilistic case.Secondly, we formally link our model to the only pre-existing denotational model of the full lambda-calculus, the quantum relational model of Pagani, Selinger and Valiron.Lastly, we prove that our game model is fully abstract, the gold standard of denotational semantics, which ensures a total correspondence between the programming language and the model. We deduce that the quantum relational model was also fully abstract, which was an open problem.This thesis is constituted of three parts. The first part details some preliminaries on category theory, used for defining a formal framework including both the quantum game model and the quantum relational model, some preliminaries on the mathematics of quantum computation, and then some preliminaries on quantum programming and its models. The second part starts with some preliminaries on game semantics and defines our quantum game model in the simplified case of the linear quantum lambda-calculus. The third part builds on the second part to define the full quantum game model, prove its full abstraction, and deduce that the quantum relational model is fully abstract too
Amriou, Tayeb. "Etude ab-initio de la strucutre électronique des composés lamellaires intercalés detype AMX2. Application aux batteries rechargeables." Artois, 2003. http://www.theses.fr/2003ARTO0405.
Повний текст джерелаThis work describes a general study of the layered compounds AMX2 (A = Li, Na ; M = Transition Metals; X = O, S, Se) usually used as positive electrode in the rechargeable batteries. First principal calculations are used to investigate the structural, electronic and electrochemical properties of theses compounds. The open circuit voltage variation is correlated to the nature of the alkali, the transition metal and the chalcogene. The results are interpreted with the charge transfer phenomena. It has been shown that the behaviour with the lithium intercalation is different from sodium intercalation. So, the understanding of the charge transfer is the key criteria to obtain a high potential
Amblard, Zoé. "Cryptographie quantique et applications spatiales." Thesis, Limoges, 2016. http://www.theses.fr/2016LIMO0113.
Повний текст джерелаThis thesis in collaboration with Thales Alenia Space studies quantum cryptographic protocols for n parties in dimension d. We first analyze the family of Bell inequalities called homogeneous Bell inequalities introduces by François Arnault in [1] and we construct several theoretical tools for a better understanding of these inequalities. With these tools, we show how to implement the measurements required to test these inequalities by using optical devices calleds multiport beamsplitters and described by Zukowski et al. in [2]. We use these devices to construct new cryptographic protocols in dimension d called hdDEB which we describe in [3]. Then, we study advantages and drawbacks of the use of quantum cryptography to protect satellite links in a noisy environment. We consider several scenarios with LEO satellites and, for each of them, we conclude about the interest of using Quantum Key Distribution protocols
Roux, Raphaël. "Étude probabiliste de systèmes de particules en interaction : applications à la simulation moléculaire." Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00597479.
Повний текст джерелаBiane, Philippe. "Quelques applications du calcul stochastique." Paris 7, 1985. http://www.theses.fr/1985PA077103.
Повний текст джерелаKachigar, Ghazal. "Questions de localisabilité pour le calcul distribué." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0339/document.
Повний текст джерелаThis thesis is divided in two parts. Its starting point is the concept of resistance to localisation, an important concept in distributed quantum computing.In the first, theoretical part of this thesis, we go over the history of certain concepts and results in quantum information theory and distributed computing, such as the phenomenon of entanglement and the non-signalling condition in the first domain, and the LOCAL model and the colouring problem in the second domain. We then focus on the φ-LOCAL model, whose goal is to study the possibility of quantum distributed algorithms, and which was developedin 2009 by adapting the non-signalling condition to the LOCAL model. We introduce the concepts of global and local consistency in order to emphasise some shortcomings of this model. Finally, we present a more adequate version ofthe φ-LOCAL model.The second part of this thesis contains our major technical results in probability theory. We define the concept of k-localisability which is a probabilistic translation of the φ-LOCAL model. We show that this concept is close to but weaker than the concept of k-dependence which is well-studied in the probabilistic literature. We mention recent results concerning 1-dependent colouring of the path graph and the conclusion they allow us to reach with regards to 1-localisable colouring of the path graph : that it is possible with four or more colours. The rest of this part is dedicated to answering the question of the possibility of 1-localisable colouring of the path graph using three colours which we will show to be impossible. In answering this question we have made use of methods in linear programming and combinatorics. In particular, we prove a theorem on the explicit solution of a linear programming problem having a certain form, and a formula for the Catalan numbers
Bohuslavskyi, Heorhii. "Electronique cryogénique et réalisation de boîtes quantiques sur substrat SOI pour le calcul quantique." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY080/document.
Повний текст джерелаThis thesis studies cryogenic electronics and quantum dots on silicon-on-insulator (SOI) for quantum computing. Different types of electron and hole quantum dots are fabricated with Leti's SOI nanowire (NW) and planar 28nm FD-SOI technology. In the first part, Pauli Spin Blockade (PSB) is studied for the first holes down to 60mK. We show that it is governed by a strong spin orbit coupling (SOC). The intradot relaxation rate of 120kHz was found for the first holes. The access barriers tunability realized with additional gates was proven to be efficient regarding the isolation of qubit from source/drain metallic leads. Following the recent demonstration of electron-dipole spin resonance (EDSR) achieved in electron quantum dots confined in the corners of silicon nanowire (CDs), we deeply investigated quantum dots in several multi-gate samples under different body-biasing conditions. Based on preliminary cryogenic transport measurements, an operation protocol for a compact two electron spin qubit gate has been proposed.Regarding cryogenic electronics required for an efficient control, manipulation and read-out of a large number of qubits, the low temperature digital and analog performance of 28nm FD-SOI MOSFETs was analysed from room temperature down to 4K. Significant improvements in transistor performance are achieved with a clear enhancement of carrier mobility and a strong reduction of subthreshold swing (SS), even for short-channel devices with gate length down to 28nm. The saturation of the subthreshold swing at low temperature is explained with a new analytical model developed in this thesis. By introducing a narrow tail in the density of states at the edges of the conduction and valence bands and using the Fermi-Dirac statistics, an excellent agreement of SS is achieved between experiments and modelling. The analysis of the SS-IDS metric under different forward body-biasing (FBB) conditions has revealed that the increased density of interface traps cannot be responsible for the SS saturation at low temperature. By adding a slight exponential variation in the interface trap density, we show that the SS-IDS curve can be well reproduced over more than 6 decades, paving a way for an efficient cryogenic design of CryoCMOS.In a second time, cryogenic performance of Ring Oscillators (RO) down to 4K was investigated. We have shown that the optimal supply voltage can be reduced down to 0.3V. This allows to efficiently reduce the dynamic and static power dissipations. At the same time, a small Energy-Delay product of 6.9fJ.ps with a delay per stage of 37ps were achieved at VDD=0.325V under aggressive FBB.Finally, in the last chapter, the duality of short-channel FD-SOI transistors operation as FETs or SETs is demonstrated at 4K. By benchmarking the QDs with respect to the common silicon platforms, we show that 28nm FD-SOI technology has a great potential for both cryogenic electronics and qubits
Rossi, François-Noël. "Etude théorique des collisions non réactives entre atomes alcalins et molécules d'hydrogène ou de deuterium : Calcul et analyse des surfaces de potentiel, application aux transitions de structure fine du rubidium." Paris 13, 1986. http://www.theses.fr/1986PA132015.
Повний текст джерелаIthier, Grégoire. "Manipulation cohérente, lecture et décohérence d'un bit quantique supraconducteur." Paris 6, 2006. https://tel.archives-ouvertes.fr/tel-00130589.
Повний текст джерелаPalafox, Jordy. "Calcul Moulien, Arborification, Symétries et Applications." Thesis, Pau, 2018. http://www.theses.fr/2018PAUU3008/document.
Повний текст джерелаThis thesis work mainly focuses on the use of the mould calculus and the technic of arborification which had been introduced both by J.Ecalle in the seventies and theirs applications to the study of continuous or discrete systems.One of the contributions is the systematic study of conditions under which the arborification allows to reestablish the convergence of formal series via introduction of a notion of invariance of mould under arborification. These results allow to give a detailed proof of Brjuno Theorem of analytic linearizability of vector fields as it is proposed by J.Ecalle in his article "Singularité non abordable par la géométrie". These results were obtained jointly with Dominique Manchon (University of Clermont Ferrand) and Jacky Cresson.The power of the mould calculus is then illustrated by an almost complete resolution of the Jarque-Villadelprat's conjecture about Hamiltonian Isochronous centers. This conjecture states that there is not existing polynomial vector fields in the plane of odd degree which are Hamiltonian. The study of the algebraic structure of the correction, introduced in the nineties by G.Gallavotti and then generalized by J.Ecalle and B.Vallet and its explicit computation via mould calculus, enables us to obtain explicit conditions of obstruction to isochronicity. The algebraic and combinatoric aspect of these objects and methods brings naturally to the classification of center conditions through a notion of complexity. The arborification allows to the unification of different approaches and a simplicification of different works, especially those of J.C.Butcher about algebraic structures of Runge-kutta methods, who had introduced that is called B-series by numerical mathematicians. Studying the algebraic structure of the substitution operator associated to a diffeomorphism, especially the one related to a Runge-Kutta method and the one which is associated to the solution of the underlying differential equations, we present the Butcher's encoding as a special translation of a direct arborification of the substitution automorphism. We can conclude that this phenomenon is wide and allows to include more recent studies on the approach by rough path of stochastic differential equations.A second part of this thesis involves the research of Lie group of symmetries of planar webs following Hénaut's approach (University of Bordeaux).This work allows to precise the relation between the dimension of the groups of symmetries and the linearizability or hexagonal character of planar webs. In the the case of line arrangement, we obtain a depthful relation between the modulus of derivations of Saito associated to the line arrangement and the group of symmetries of the associated web
Cirstea, Horatiu. "Calcul de réécriture : fondements et applications." Nancy 1, 2000. http://www.theses.fr/2000NAN10037.
Повний текст джерелаThis thesis is devoted to the study of a calculus that describes the application of conditional rewriting rules and the obtained results at the same level of representation. We introduce the rewriting calculus, also called the rho-calculus, which generalizes the first order term rewriting and lambda-calculus, and makes possible the representation of the non-determinism. In our approach the abstraction operator as weIl as the application operator are objects of calculus. The result of a reduction in the rewriting calculus is either an empty set representing the application failure, or a singleton representing a deterministic result, or a set having several elements representing a not-deterministic choice of results. In this thesis we concentrate on the properties of the rewriting calculus where a syntactic matching is used in order to bind the variables to their current values. We define evaluation strategies ensuring the confluence of the calcalus and we show that these strategies become trivial for restrictions of the general rewriting calculus to simpler calculi like the lambda-calculus. The rewriting calculus is not terminating in the untyped case but the strong normalization is obtained for the simply typed calculus. In the rewriting calculus extended with an operator allowing to test the application failure we define terms representing innermost and outermost normalizations with respect to a set of rewriting rules. By using these terms, we obtain a natural and concise description of the conditional rewriting. Finally, starting from the representation of the conditional rewriting rules, we show how the rewriting calculus can be used to give a semantics to ELAN, a language based on the application of rewriting rules controlled by strategies
Rousseau, Emmanuel. "Evaluation expérimentale d'éléments de calcul quantique (qubit) formés d'électrons piégés sur l'hélium liquide." Phd thesis, Université Paris Sud - Paris XI, 2006. http://tel.archives-ouvertes.fr/tel-00250371.
Повний текст джерелаLa première étape dans la réalisation de ce qubit consiste à piéger et à contrôler un unique électron. Ceci a été réalisé grâce à un jeu d'électrodes micro-fabriquées définissant un puits de potentiel dans lequel l'électron est piégé. Nous sommes capables avec un tel échantillon de piéger et de détecter un nombre variables d'électrons entre 1 et une vingtaine.
Cela nous a alors permis d'étudier le comportement statique d'un petit nombre d'électrons dans un piège. Ils sont supposés cristallisés et formés des structures appelées molécules de Wigner. De telles molécules n'ont pas encore été observées avec des électrons au-dessus de l'hélium. Sans apporter de preuves formelles, nos résultats sont en faveur d'une cristallisation de Wigner.
Nous avons ensuite essayé de caractériser plus précisément le qubit. Nous avons cherché à réaliser une lecture projective (dépendant de l'état du qubit) et une mesure du temps de relaxation. Les résultats ont été obtenus en excitant l'électron par un champ électrique incohérent. Une mesure propre du temps de relaxation nécessiterait un champ électrique cohérent. La conclusion ne peut donc pas être définitive mais il semblerait que le temps de relaxation soit plus court que calculé théoriquement. Cela est peut-être dû à une mesure de la relaxation entre les états d'oscillations dans le piège et non entre les états du qubit.
AL, SALEH-MAHROUSSEH SALOUA. "Calcul relativiste, en electrodynamique quantique, de la diffusion compton sur un electron lie." Clermont-Ferrand 2, 1988. http://www.theses.fr/1988CLF21098.
Повний текст джерелаAl, Saleh-Mahrousseh Saloua. "Calcul relativiste, en électrodynamique quantique, de la diffusion Compton sur un électron lié." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37618406p.
Повний текст джерелаMignard, Michaël. "Invariants numériques de catégories de fusion : calculs et applications." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCK015.
Повний текст джерелаPointed fusion categories are fusion categories in which all simple objects are invertible. We develop computer-based methods to classify pointed categories up to Morita equivalence, and apply them to pointed fusion categories of dimension from 2 to 31. We prove that there are 1126 Morita classes of such categories. Also, we prove that the Frobenius-Schur indicators of the centers of a pointed category of dimension less than 32, along with its ribbon twist, determine its Morita class. This is not true in general: the modular data, and a fortiori the indicators and the ribbon twists, do not distinguish modular categories. We give a family of examples; in fact, arbitrarly many pairwise non-equivalent modular categories can share the same modular data
Douce, Tom. "Realistic quantum information processing : from devices to computational models." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC201/document.
Повний текст джерелаThe theory of quantum computing lies at the very boundary between quantum physics and computer science. As such, both fields bring their own methods and mathematical tools to make quantum computing even richer. The present thesis attempts to reflect this specificity by addressing questions ranging from experimental physics to computational models. The goal is to provide novel ways of demonstrating quantum advantage. After a short introduction to basic notions of quantum mechanics, some computer science aspects are discussed. We describe the powerful formalism of quantum complexity classes and the concept of quantum computations based on continuous variables. We then translate the model of instantaneous quantum computing to continuous variables, which is experimentally appealing. The chapter concludes with a discussion on a hybrid protocol involving Grover’s algorithm in a quantum communication framework. The last part of the thesis is devoted to experimentally driven issues. A fundamental connection between the Hong-Ou-Mandel experiment and the Wigner function of two-photon states is derived and a verification protocol is designed accordingly. We then move to the field of superconducting circuits to discuss proposals for future experiments. We show how to use a flux qubit to manipulate a NV color center. We also describe how to use to probe the Rabi model in the ultra strong coupling regime using an additional weakly coupled qubit
Coviello, Rosanna. "Calcul stochastique via régularisation et applications financières." Phd thesis, Université Paris-Nord - Paris XIII, 2006. http://tel.archives-ouvertes.fr/tel-00121525.
Повний текст джерелаNous fournissons des exemples de portefeuilles autofinancés et introduisons une notion de A-martingale. Un calcul relatif à celle-ci est développé. La condition de non-arbitrage parmi toutes les stratégies dans A est récupérée si le processus des prix de l'actif risqué est une A-martingale.
Nous abordons le problème de la viabilité du marché, de la couverture et de la maximisation de l'utilité de la richesse terminale.
La deuxième partie de la thèse est consacrée à l'étude d'une équation différentielle stochastique unidimensionnelle dirigée par une semimartingale mélangée à un processus à variation cubique finie.
Nous proposons une méthode qui repose sur une transformation réduisant le coefficient de diffusion à 1.
Le développement de la méthode utilisée nous conduit à des résultats significatifs dans l'analyse du calcul via régularisation.
En particulier, une formule de type Ito-Wentzell relative aux processus à variation cubique finie est
établie et la structure des processus weak-Dirichlet par rapport à la filtration brownienne est clarifiée.
Nous démontrons, par une approche similaire, l'existence et l'unicité d'une équation dirigée par un processus hölder-continu dans l'espace. En utilisant une formule d'Ito pour les semimartingales réversibles nous prouvons l'existence d'une solution lorsque le processus dirigeant l'équation est le mouvement brownien et le coefficient de diffusion est juste continu
Mora, Frédéric. "Visibilité polygone à polygone : calcul, représentation, applications." Phd thesis, Université de Poitiers, 2006. http://tel.archives-ouvertes.fr/tel-00090127.
Повний текст джерелаNous proposons un nouvel algorithme pour calculer la visibilité dans l'espace de Plücker, afin de minimiser les coûts en temps et mémoire vis-à-vis des précédentes approches.
En synthèse d'images, nous utilisons l'information ainsi calculée pourproposer une nouvelle solution au calcul analytique des ombres douces en illumination directe. Cette solution concilie la qualité et la rapidité du rendu.
En propagation électromagnétique, nous proposons l'optimisation sans perte d'un modèle basé rayons. Celle-ci permet d'effectuer des simulations dont la précision est optimale tout en s'appliquant à des environnements de tailles significatives.
Hochet, Bertrand. "Conception de VLSI : applications au calcul numérique." Grenoble INPG, 1987. http://www.theses.fr/1987INPG0005.
Повний текст джерелаSénéchaud, Pascale. "Calcul formel et parallélisme : bases de Gröbner booléennes, méthodes de calcul : applications, parallélisation." Grenoble INPG, 1990. http://tel.archives-ouvertes.fr/tel-00337227.
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