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Cet article étudie le Congrès mondial de science politique organisé à Moscou en 1979 par l’Association internationale de science politique (AISP). En démontrant que cette manifestation n’est pas politique par essence, il entend contribuer à une analyse des rapports entre science politique et pouvoir politique au xxe siècle. Il met d’abord au jour les conditions de possibilité d’un tel événement et montre que, dans le contexte de la guerre froide, la tenue du congrès s’explique par les formes de politisation et de dépolitisation dont il fait alternativement l’objet. L’article analyse ensuite le déroulement du congrès et plus particulièrement les mobilisations de certains savants soviétiques, qui le constituent en ressource pour œuvrer à l’institutionnalisation de la science politique en URSS. Enfin, l’article revient sur les effets politiques et scientifiques de l’événement et avance l’idée selon laquelle le congrès contribue à faire évoluer l’espace du politiquement dicible en URSS par la figure du politologue qu’il valorise et inscrit dans un univers médiatique soviétique. L’article insiste aussi sur le fait que l’événement modifie durablement les pratiques de l’AISP et, de ce fait, les logiques d’internationalisation de la discipline. This article focuses on the World Congress of Political Science organised in Moscow in 1979 by the International Political Science Association (IPSA). By showing that this event is not political in essence, the article seeks to contribute to an analysis of the relationship between political science and political power in the 20th century. We start by examining the conditions of possibility of such an event, showing that the holding of the Congress, in the context of the Cold War, can be explained by the forms of politicisation and depoliticisation to which it was alternately subjected. We then analyse the congress itself and, more particularly, the mobilisation of certain Soviet scholars, who harnessed it to working towards institutionalising political science in the Union of Soviet Socialist Republics (USSR). Lastly, the article returns to the political and scientific effects of this event, and suggests that the congress helped develop the space of what could be expressed politically in the USSR, through the figure of the political scientist, which it valorises and inscribes within the world of the Soviet media. The article also insists on the fact that the event lastingly modified the practices of the IPSA and, consequently, the logics of internationalisation of the discipline.

Dans cet entretien, Stephen Anthony Smith, historien des communismes et ancien éditeur de la revue Past and Present, évoque tant les origines de son parcours intellectuel que l'évolution de ses approches et objets dans l'appréhension des mondes ouvrier et paysan soviétique et chinois. En s'interrogeant sur les héritages du marxisme et plus particulièrement sur ses voies de redéfinition, ses réappropriations, ses usages et ses emprunts, il revient sur les mutations qu'a connues le paradigme de l'histoire sociale notamment autour des notions de classes sociales, de nationalisme et de cultures populaires. En rendant compte du tournant culturel puis global en histoire – et des apports d'une histoire comparée des communismes à laquelle Stephen A. Smith prit une part active – l'entretien permet de souligner les manières dont l'histoire sociale des communismes peut contribuer à penser les cultures des classes populaires et concourir à expliciter leur rapport au politique. In this interview, Stephen Anthony Smith, historian of communism and former editor of the review Past and Present, discusses both the origins of his intellectual career and the evolution of his approaches and topics of research in relation to the worlds of the workers and peasants of Russia and China. By examining the legacy of Marxism and more particularly its redefinition, reappropriation, uses and modifications in the light of the contributions of the social sciences, he reviews the mutations that the paradigm of social history has undergone, particularly with regard to conceptions of social classes, nationalism and popular cultures. By giving an account of the cultural and global turns in historical scholarship, and of the contributions of a comparative history of communism, which he has helped develop, the interview highlights the ways in which the social history of communism can contribute to thinking about the cultures of the popular classes and help to specify their relationship to politics.

Defence date: 15 December 2017 Examining Board: Prof. Stephen Anthony Smith, Oxford University (Supervisor); Prof. Michel Offerlé, Ecole Normale Supérieure (Ulm) (Co-supervisor); Prof. Alexander Etkind, European University Institute; Prof. David Priestland, Oxford University The Moscow State Institute of International Relations (MGIMO) was founded after the Soviet victory at Stalingrad in 1943 with the mission of training a new generation of flag bearers of Communist ideals and Soviet State interests on the international scene, the so-called meždunarodniki. Often cited as the alma mater of most of the leading figures involved in the conduct of the Soviet diplomacy during Cold War, the MGIMO has received paradoxically little attention from scholars. Most researchers who have mentioned it present the Institute either as a crucible of social reproduction in the 1970s Soviet Union or as a subversive place, whose ‘net thinking’ paved the way to Gorbachev’s perestroika. For their part, numerous meždunarodniki describe the MGIMO as a Soviet Tsarskoye Selo or a Communist Lyceum: they surprisingly refer to their experience at the Institute in terms redolent of Russian imperial history, stressing the fact that they were much more than experts in foreign affairs and that they occupied a distinct place within the Soviet elite. Ranging from the end of World War II to the collapse of the USSR, this research aims at analyzing the making of a hybrid social category, what I describe as Party nobility in the Soviet Union, the identity of which shaped and was shaped by the Cold War. How did an institution and its alumni form a distinct social group that sat at the very core of the Cold War enterprise? How did MGIMO become the place where a specific praxis of foreign affairs was inculcated, based on the hybridisation of aristocratic manners and communist ethics during the Khrushchev and the Brezhnev era? Why was the loyalty of both the institution and the social group put into question during perestroika as early as 1985? These are some of the main questions this research will answer.

In recent years, the scientifical community has succeeded in experimentally building simple quantum systems on which series of measurements are successively acquired along quantum trajectories, without any reinitialization of their state (density operator) by the physicist. The subject of this thesis is to adapt the quantum tomography techniques (state and parameters estimation) to this frame, in order to take into account the feedback of the measurement on the state, the decoherence and experimental imperfections.During the measurement process, the evolution of the quantum state is then governed by a hidden-state Markov process (Belavkin quantum filters). Concerning continuous-time measurements, we begin by showing how to discretize the stochastic master equation, while preserving the positivity and the trace of the quantum state, and so reducing to discrete-time quantum filters. Then, we develop,starting from trajectories of discrete-time measurements, some maximum-likelihood estimation techniques for initial state and parameters. This estimation is coupled with its confidence interval. When it concerns the value of parameters (quantum process tomography), we provide a result of robustness using the formalism of particular filters, and we propose a maximization technique based on the calculus of gradient by adjoint method, which is well adapted to the multi-parametric case. When the estimation concerns the initial state (quantum state tomography), we give an explicit formulation of the likelihood function thanks to the adjoint states, show that its logarithm is a concave function of the initial state and build an intrinsic expression of the variance, obtained from asymptotic developments of Bayesian means, lying on the geometry of the space of density operators.These estimation techniques have been applied and experimentally validated for two types of quantum measurements: discrete-time non-destructive measurements of photons in the group of cavity quantum electro-dynamics of LKB at Collège de France, diffusive measurements of the fluorescence of a supra-conducting qubit in the quantum electronics group of LPA at ENS Paris.; La communauté scientifique a réussi ces dernières années à bâtir des systèmes quantiques simples sur lesquels des séries de mesures sont acquises successivement le long de trajectoires quantiques et sans réinitialisation de l’état (opérateur densité) par l’expérimentateur.L’objet de cette thèse est d’adapter les méthodes de tomographie quantique (estimation d’état et de paramètres) à ce cadre pour prendre en compte la rétroaction de la mesure sur l’état, la décohérence et les imperfections expérimentales.Durant le processus de mesure, l’évolution de l’état quantique est alors gouvernée par un processus de Markov à états cachés (filtres quantiques de Belavkin). Pour des mesuresen temps continu, nous commençons par montrer comment discrétiser l’équation maîtresse stochastique tout en préservant la positivité et la trace de l’état quantique, et ainsi sera mener aux filtres quantiques en temps discret. Ensuite, nous développons, à partir de trajectoires de mesures en temps discret, des techniques d’estimation par maximum de vraisemblance pour l’état initial et les paramètres. Cette estimation est accompagnée de son intervalle de confiance. Lorsqu’elle concerne des valeurs de paramètres (tomographie de processus quantique), nous donnons un résultat de robustesse grâce au formalisme des filtres particulaires et nous proposons une méthode de maximisation fondée sur le calcul du gradient par l’adjoint et bien adaptée au cas multiparamétrique. Lorsque l’estimation porte sur l’état initial (tomographie d’état quantique), nous donnons une formulation explicite de la fonction de vraisemblance grâce aux états adjoints, montrons que son logarithme est une fonction concave de l’état initial et élaborons une expression intrinsèque de la variance grâce à des développements asymptotiques de moyennes bayésiennes et reposant sur la géométrie de l’espace des opérateurs densité.Ces méthodes d’estimation ont été appliquées et validées expérimentalement pour deux types de mesures quantiques : des mesures en temps discret non destructives de photons dans le groupe d’électrodynamique quantique en cavité du LKB au Collège de France, des mesures diffusives de la fluorescence d’un qubit supraconducteur dans le groupe d’électronique quantique du LPA à l’ENS Paris.

In recent years, the scientifical community has succeeded in experimentally building simple quantum systems on which series of measurements are successively acquired along quantum trajectories, without any reinitialization of their state (density operator) by the physicist. The subject of this thesis is to adapt the quantum tomography techniques (state and parameters estimation) to this frame, in order to take into account the feedback of the measurement on the state, the decoherence and experimental imperfections.During the measurement process, the evolution of the quantum state is then governed by a hidden-state Markov process (Belavkin quantum filters). Concerning continuous-time measurements, we begin by showing how to discretize the stochastic master equation, while preserving the positivity and the trace of the quantum state, and so reducing to discrete-time quantum filters. Then, we develop,starting from trajectories of discrete-time measurements, some maximum-likelihood estimation techniques for initial state and parameters. This estimation is coupled with its confidence interval. When it concerns the value of parameters (quantum process tomography), we provide a result of robustness using the formalism of particular filters, and we propose a maximization technique based on the calculus of gradient by adjoint method, which is well adapted to the multi-parametric case. When the estimation concerns the initial state (quantum state tomography), we give an explicit formulation of the likelihood function thanks to the adjoint states, show that its logarithm is a concave function of the initial state and build an intrinsic expression of the variance, obtained from asymptotic developments of Bayesian means, lying on the geometry of the space of density operators.These estimation techniques have been applied and experimentally validated for two types of quantum measurements: discrete-time non-destructive measurements of photons in the group of cavity quantum electro-dynamics of LKB at Collège de France, diffusive measurements of the fluorescence of a supra-conducting qubit in the quantum electronics group of LPA at ENS Paris.; La communauté scientifique a réussi ces dernières années à bâtir des systèmes quantiques simples sur lesquels des séries de mesures sont acquises successivement le long de trajectoires quantiques et sans réinitialisation de l’état (opérateur densité) par l’expérimentateur.L’objet de cette thèse est d’adapter les méthodes de tomographie quantique (estimation d’état et de paramètres) à ce cadre pour prendre en compte la rétroaction de la mesure sur l’état, la décohérence et les imperfections expérimentales.Durant le processus de mesure, l’évolution de l’état quantique est alors gouvernée par un processus de Markov à états cachés (filtres quantiques de Belavkin). Pour des mesuresen temps continu, nous commençons par montrer comment discrétiser l’équation maîtresse stochastique tout en préservant la positivité et la trace de l’état quantique, et ainsi sera mener aux filtres quantiques en temps discret. Ensuite, nous développons, à partir de trajectoires de mesures en temps discret, des techniques d’estimation par maximum de vraisemblance pour l’état initial et les paramètres. Cette estimation est accompagnée de son intervalle de confiance. Lorsqu’elle concerne des valeurs de paramètres (tomographie de processus quantique), nous donnons un résultat de robustesse grâce au formalisme des filtres particulaires et nous proposons une méthode de maximisation fondée sur le calcul du gradient par l’adjoint et bien adaptée au cas multiparamétrique. Lorsque l’estimation porte sur l’état initial (tomographie d’état quantique), nous donnons une formulation explicite de la fonction de vraisemblance grâce aux états adjoints, montrons que son logarithme est une fonction concave de l’état initial et élaborons une expression intrinsèque de la variance grâce à des développements asymptotiques de moyennes bayésiennes et reposant sur la géométrie de l’espace des opérateurs densité.Ces méthodes d’estimation ont été appliquées et validées expérimentalement pour deux types de mesures quantiques : des mesures en temps discret non destructives de photons dans le groupe d’électrodynamique quantique en cavité du LKB au Collège de France, des mesures diffusives de la fluorescence d’un qubit supraconducteur dans le groupe d’électronique quantique du LPA à l’ENS Paris.

International audience; When the main source of qubit relaxation comes from its coupling to a photonic channel, each relaxation event is associated with the release of a photon. The corresponding discrete quantum jumps of the qubit state can be observed by counting the number of photons emitted by fluorescence. This discreteness of the quantum jumps is in fact related to the nature of the light detector. What does the evolution of the qubit state become if fluorescence is measured using a heterodyne detector instead? In this talk, an experiment will be discussed, in which the records of heterodyne measurements of fluorescence is used to reconstruct the quantum trajectories of a qubit during relaxation. Using a large number of experiments, it is shown that these trajectories can be used to better predict the probability to find given measurement outcomes during the evolution. This heterodyne measurement of the fluorescence is a quantum demolition continuous measurement, which is very different from the more common dispersive measurement sensitive to qubit occupation. These trajectories are thus expected to exhibit some exotic properties, particularly when using past and future knowledge. Besides, using measurement based feedback based on the fluorescence signal alone, it is possible to stabilize any chosen qubit state. This work thus demonstrates that relaxation into an efficiently monitored channel is not a limit for quantum information protocols but can instead be a resource.

International audience; This paper studies calendar spreads in commodity futures markets while taking into account a stochastic convenience yield. We show that a convenience yield imperfectly correlated with the spot commmodity price results in an optimal strategy composed of two commodity futures contracts. These strategies reveal a calendar spread effect through the positive correlation between the two futures contracts. These strategies can easily be computed and analyzed under the Samuelson hypothesis.

International audience; This papers develops a partial equilibrium model of the convenience yield risk premium. Contrary to the previous literature, the risk premium is computed explicitely and endogenously. We provide a decomposition of the convenience yield risk premium in terms of the volatility of the convenience yield as well as in terms of the sensitivity of the marginal utility of investors to the movements of the convenience yield. This decomposition enables us to assess the impact of the risk aversion and investment horizon of investors on the futures contracts' basis and on the term structure of volatility for our illustration carried out in the case of the copper market.