Tesis sobre el tema "Atomes dipolaires"
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Schlosser, Nicolas. "Etude et réalisation de micro-pièges dipolaires optiques pour atomes neutres". Phd thesis, Université Paris Sud - Paris XI, 2001. http://tel.archives-ouvertes.fr/tel-00001195.
Texto completol'implémentation de portes logiques quantiques. Dans ce contexte, cette étude
porte sur la réalisation d'un piège dipolaire optique de si petite taille qu'il
ne puisse contenir qu'un atome unique. Pour cela, il est nécessaire de
focaliser très fortement un laser à l'endroit où l'on désire capturer les
atomes. L'expérience s'articule donc autour d'un objectif de microscope de
grande ouverture numérique, entièrement conçu et réalisé au laboratoire. Cette
optique est utilisée pour faire focaliser un laser au centre d'un piège
magnéto-optique, réservoir d'atomes froids alimentant le piège dipolaire ainsi
créé.
Le dispositif d'observation des atomes piégés est basé sur le même objectif,
qui collecte, avec une grande efficacité, la fluorescence des atomes piégés et
en fait l'image sur une caméra CCD ou une photodiode à avalanche. La résolution
spatiale du dispositif utilisant la caméra permet d'obtenir une image des
atomes capturés, alors que l'on utilise la rapidité de la photodiode à
avalanche pour les études de la dynamique du piège avec une bonne résolution
temporelle.
Après une description détaillée de ce dispositif expérimental, nous montrons
qu'il est possible de réaliser des micro-pièges dipolaires optiques, de
quelques microns cube et contenant une dizaine d'atomes. L'étude de la
dynamique de chargement et de la durée de vie de ces pièges révèle également la
présence de processus de collisions à deux corps. Nous montrons ensuite qu'en
diminuant le taux de chargement il est possible d'observer, en temps réel, un
atome unique piégé pendant quelques secondes. Dans ce régime, un processus de
"blocage collisionnel" limite ce nombre d'atome à un. Pour finir, nous
décrirons la mise en place d'un double piège dipolaire, dans lequel on peut
piéger un atome unique dans chaque site. Ce dispositif ouvre la voie vers
l'étude de l'interaction entre atomes piégés individuellement.
Bouazza, Chayma. "Gaz de dysprosium ultrafroid dans des pièges dipolaires optiques : contrôle des interactions entre atomes fortement magnétiques". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEE012/document.
Texto completoIn this thesis, I present the study of the laser trapping and cooling of a Dysprosium atomic gas. This latter belong to the lanthanide family, it exhibits a large angular momentum in its electronic ground state, making it a suitable candidate for investigating dipolar quantum gases. These systems present a major interest as they can lead to the observation of novel quantum phenomena thanks to the anisotropic and long-range character of the interaction between magnetic dipoles. Moreover, Dysprosium has a rich electronic structure offering the possibility to implement strong light-spin coupling with a reduced heating with respect to alkali species, which paves the way toward the realization of synthetic gauge fields.In this work, I present the experimental investigation of different interaction mechanisms occurring in an ultracold gas of Dysprosium, ranging from light-assisted collisions to dipolar relaxation and evaporative cooling. I expose also the experimental realization of an effective magnetic field, using spin-dependent light-shift, allowing optical control over atomic interactions by means of Feshbach resonances
Houde, Olivier. "Réalisation d'éléments d'optique atomique : études d'un guide, d'une lame séparatrice dipolaire et d'un miroir concave magnétique". Paris 11, 2002. http://www.theses.fr/2002PA112229.
Texto completoThe topic of this work deals with the realization of atom optic elements. We have developed and studied three elements: a dipole guide, a dipole beam-splitter and a magnetic concave mirror. These elements have been analysed by studying their influence on a 87Rb cold atoms cloud in propagation due to gravity. Cold atoms are produced in a magneto-optical trap. The atomic guide uses the dipole force created by a far red-detuned, vertically directed, TEM_00 laser beam. The dipole interaction leads to a potential well with finite depth, which transversally confine a large part of the atoms during their propagation. The guiding atoms do not expand due to their temperature. We have guided 15% of the atoms over a 30 cm distance. The beam-splitter uses the dipole force created by two crossed dipole guides, the first one along the vertical direction and the second one along an oblique direction at an angle of 0. 12 rad from the vertical. The atoms are first guided by the vertical guide along a 4 mm distance. Then the oblique guide is switched on. In the overlap region of the two crossing guides, the initial cloud is split. At the beam-splitter output, we obtain two clouds separated from about 1 mm. The splitter efficiency is about 40%. The magnetic concave mirror uses the Stern and Gerlach effect. After a 2 mm fall in the gravity field, the atoms are submitted to a magnetic field gradient created by two coils in the anti-Helmholtz configuration. This magnetic field induces cloud bounces because it creates a potential well in which the cloud oscillates and undergoes transverse focalisations. We have observed two bounces and multiple focalisations
Fossez, Kévin. "Réactions de capture radiative et spectroscopie d'anions multipolaires dans le cadre du Gamow Shell Model". Caen, 2014. http://www.theses.fr/2014CAEN2018.
Texto completoSmall open quantum systems, whose properties are profoundly affected by the environment of continuum states, are intensely studied in various fields of Physics: nuclear physics, atomic and molecular physics, quantum optics, etc. These different many-body systems, in spite of their specific features, have generic properties which are common to all weakly bound or unbound systems close to the threshold. Coupling to the continuum is essential to describe the low-energy nuclear reactions of astrophysical interest, the formation of halo states in nuclei, atomic clusters and dipolar anions, or the near-threshold two neutron and alpha particle correlations (clustering). Recently, the open quantum system extension of the nuclear shell model, the Gamow shell model (GSM), based on the Berggren ensemble, has been applied successfully for the description of resonant states spectra in atomic nuclei. The coupled-channel formulation of the GSM (GSM-CC) allows to describe various low-energy nuclear reactions. In this work, the GSM-CC is formulated and applied for the description of proton/neutron radiative capture reactions of astrophysical interest, such as: 17F ( p , gamma ) 18Ne, 7Be ( p , gamma ) 8B and 7Li ( n , gamma ) 8Li. Moreover, for the first time, the GSM has been applied in atomic physics for the description of spectra of dipolar anions. Systematic investigation of the hydrogen cyanide dipolar anion (HCN-) allowed to identify the collective bands of states both in the strong coupling regime, for weakly bound halo states, and in the weak coupling regime above the dissociation threshold. In the strong coupling regime, K_J = 0 anion a rotational band has been found. Above the threshold, K_J quantum number is not conserved. Resonances in this regime form rotational bands according to the angular momentum of the rotating molecule, whereas the bandhead energies and the lifetimes depend predominantly on the external electron wave function
Trifa, Youssef. "Dynamiques de corrélations et d'intrication dans des gaz d'atomes froids". Electronic Thesis or Diss., Lyon, École normale supérieure, 2024. http://www.theses.fr/2024ENSL0018.
Texto completoThe quantum many-body problem, and especially the study of dynamical properties of a multipartite quantum system, is one of the hardest problems of modern physics. There exist only a few analytical results and exact numerical simulations require an amount of resources that grow exponentially with the system size.In this thesis, we studied correlations and entanglement properties for systems composed of magnetic atoms on a lattice, for instance via the generation of spin squeezing. For this purpose we have developed new approximate numerical methods that allow us to study large system sizes. This enabled us to propose protocols to generate an amount of spin squeezing that scales with the system size. The advantage is twofold. Since spin squeezing is an entanglement witness, this would allow for entanglement detection in a system of magnetic atoms - which has yet to be realized experimentally. Moreover, spin squeezing offers an important metrological advantage, asspin-squeezed states can be used for extremely precise measurements of external magnetic fields, far beyond what one can achieve within dependent atoms.Finally, we studied the generation of other forms of entanglement, namely Dicke squeezing (of spin or momentum), in systems of Bose condensed atoms. This form of entanglement is well-known in spin-1 atomic condensates. Here, we propose a protocol to generalize it to the case of momentum modes, using a time-dependent Hamiltonian. The entangled states generated during the dynamics are potentially useful for the precision measurements of inertial forces
Celistrino, Teixeira Raul. "Effets mécaniques de l'interaction dipolaire des atomes de Rydberg sondés par spectroscopie microonde". Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066224/document.
Texto completoThe typical energy scales that arise from dipolar interaction between Rydberg atoms are orders of magnitude bigger than those related to the interaction between atoms and molecules at the ground level. A length scale of several micrometres stems from that strong interaction, which is the cause of the so-called dipole blockade effect, or the suppression of excitation of Rydberg atoms within dense atomic clouds. In the first part of this thesis, we study the possibility of using this effect to the deterministic excitation of a single atom within a Bose-Einstein condensate in a magnetic trap created on an atom chip. In a second part, we study the dipolar interaction of Rydberg atoms in dense ensembles, through microwave spectroscopy of transitions between Rydberg levels close in energy. These ensembles are created by laser excitation of Rb87 atoms initially in the ground level, trapped in a dense, cold cloud. The spectra of the microwave transitions are broadened and shifted, due to dipolar interaction. The study of these spectra then allows to infer several aspects of the spatial distribution of the Rydberg atoms, which reveals different excitation processes depending whether the laser light is in resonance or shifted with respect to the Rydberg transition. The mechanical evolution of the Rydberg atom cloud as a function of their mutual repulsive interaction was also observed, by performing microwave spectroscopy at different delays from the laser excitation. By these observations we show that, for time scales bigger than 10µs, their movement must be taken into account if one wants to understand the dynamics of the Rydberg excitation in dense atomic clouds
Cantat-Moltrecht, Tigrane. "Atomes de Rydberg en interaction : des nuages denses d'atomes de Rydberg à la simulation quantique avec des atomes circulaires". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEE001/document.
Texto completoInteracting many-body quantum systems are at the heart of contemporary research in quantum physics. The understanding of such systems is crucial to the development of condensed-matter physics. Many research efforts aim at building a "quantum simulator": a platform which allows to model a hard-to-access quantum system with a more controllable one. Ensembles of Rydberg atoms, thanks to their strong dipolar interactions, make for an excellent system to study many-body quantum physics. We present here a study of the excitation of a dense cloud of interacting Rydberg atoms. This study was conducted on an experimental setup mixing on-chip cold atoms techniques with Rydberg atoms manipulation techniques. The result of this study leads us to make a full-fledged proposal for the realisation of a quantum simulator, based on trapped circular Rydberg atoms. The proposed simulator is particularly promising due to its flexibility and to the long simulation times for which it would allow. We conclude this manuscript with a detailed description of the first experimental step towards building such a simulator: the on-chip excitation of circular Rydberg atoms
Nguyen, Thanh Long. "Study of dipole-dipole interaction between Rydberg atoms : toward quantum simulation with Rydberg atoms". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066695/document.
Texto completoQuantum simulation offers a highly promising way to understand large correlated quantum systems, and many experimental platforms are now being developed. Rydberg atoms are especially appealing thanks to their strong and short-range dipole-dipole interaction. In our setup, we prepare and manipulate ensembles of Rydberg atoms excited from an ultracold atomic cloud magnetically trapped above a superconducting chip. The dynamics of the Rydberg excitation can be controlled through the laser excitation process. The many-body atomic interaction energy spectrum is then directly measured through microwave spectroscopy. This thesis develops a rigorous Monte Carlo model that provides an insight into the excitation process. Using this model, we discuss a possibility to explore quantum simulations of energy transport in a 1D chain of low angular momentum Rydberg atoms. Furthermore, we propose an innovative platform for quantum simulations. It relies on a groundbreaking approach, based on laser-trapped ensemble of extremely long-lived, strongly interacting circular Rydberg atoms. We present intensive numerical results as well as discuss a wide range of problems that can be addressed with the proposed model
Perrin, Hélène. "Refroidissement d'atomes de césium confinés dans un piège dipolaire très désaccordé". Phd thesis, Université Pierre et Marie Curie - Paris VI, 1998. http://tel.archives-ouvertes.fr/tel-00003896.
Texto completoDans une première série d'expériences, on superpose au piège un réseau interférentiel unidimensionnel de pas comparable à la longueur d'onde optique. On peut résoudre la structure vibrationnelle induite avec les transitions Raman. Les atomes sont refroidis dans ce réseau par la méthode du refroidissement par bandes latérales initialement développée pour les ions et appliquée pour la première fois ici aux atomes neutres. On prépare ainsi un échantillon d'atomes froids avec 90% des atomes dans le niveau fondamental du réseau.
Cette thèse présente également les résultats obtenus sur les atomes piégés par refroidissement Raman. Cette technique, très efficace à une dimension sur les atomes libres, est étendue à trois dimensions sur des atomes piégés, polarisés ou non. On a développé ici une méthode permettant simultanément de polariser et de refroidir les atomes en utilisant la transition Raman. On obtient des températures de l'ordre de 2 µK avec des densités atomiques de l'ordre de 10^12 atomes/cm3, ce qui représente un gain de trois à quatre ordres de grandeur par rapport à un piège magnéto-optique. On montre que la limite atteinte est due à la réabsorption par les atomes refroidis de photons résonnants issus du repompage. En réduisant volontairement la densité atomique, on limite la réabsorption, ce qui permet d'atteindre des températures encore plus basses (680 nK).
Dreon, Davide. "Designing and building an ultracold Dysprosium experiment : a new framework for light-spin interaction". Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEE036/document.
Texto completoIn this thesis I present the construction of a new experiment producing ultra cold gases of Dysprosium. Using the favourable electronic structure of open-shell lanthanide atoms, we aim at the realisation of laser-induced synthetic gauge fields, which could lead to the observation of novel (topological) phases of matter. The coupling of the atomic spin with the light field, improved with respect to alkali atoms, opens the possibility to explore strongly interacting regimes that were up to now out of experimental reach. I adapt existing protocols for the implementation of gauge fields to the case of Dysprosium, taking into account its large electronic spin (J = 8 in the ground state). Moreover, Dysprosium has the largest magnetic moment among the stable elements, and is the best candidate for the study of dipolar gases. I describe the experimental setup that we built and how we perform the trapping and cooling of Dysprosium. We study in detail the behaviour of the magneto-optical trap, which is performed on the ¹S₀ ↔ ³P₁ intercombination line. The narrow linewidth and the large spin make the trap operation quite challenging. Nevertheless, I show that its understanding becomes quite simple in the regime where the cloud spontaneously polarises due to the interplay of optical and gravitational forces. Finally, I describe the last steps of optical transport and evaporation, which will lead to the production of a degenerate gas
Clément, Jean-François. "Réalisation d'un condensat de Bose-Einstein dans un piège dipolaire optique à 1565 nm". Phd thesis, Université Paris Sud - Paris XI, 2008. http://tel.archives-ouvertes.fr/tel-00343970.
Texto completoStern, Guillaume. "Stratégies pour le chargement d’un piège dipolaire d’atomes froids de césium et le refroidissement évaporatif". Paris 11, 2008. http://www.theses.fr/2008PA112077.
Texto completoCesium atom was condensed for the first time in 2002. A dipolar trap was required to trap the atoms in their fundamental ground state, in which two bodies collisionnal process are suppressed. Our strategy, to reach quantum degeneracy, consists in loading a tight dipolar trap with a magnetic trap. Once the magnetic trap is switched off, the “hot” but dense dipolar trap could allow a very fast evaporative cooling while limiting the three bodies recombinations. Simulations of the loading and evaporation process, taking into account several pertinent phenomena, have been developed. They show different schemes, which could allow us to reach to the condensation in a time of the second order with several tens of thousands atoms. The previous experimental setup has been modified to fit this new strategy. The main changes were the improvements of the vacuum system, and the transfer by using a pushing beam. A simple or crossed dipolar trap has been built. Performances of the loading of a simple dipolar trap with a magnetic trap have been compared with the performances of the loading with an optical molasses. They were better and our model reproduces quite fairly the results we obtained. In the case of a loading of a crossed dipolar trap, the results were much worse what we expected. A loading with a compressed MOT gives similar results, and it’s with a molasses that the loading is the most successful
Cartarius, Florian. "Phases classiques et quantiques des systèmes dipolaires de basse dimensionnalité". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY049.
Texto completoIn this work, the classical and quantum phases of low-dimensional atomic or molecular systems is studied with a particular focus on the regime where a system goes over from a strictly one-dimensional to a two dimensional system.The first part of the thesis is dedicated to atoms interacting via contact interactions. In particular, we study the dynamical depinning following a sudden turn off of an optical lattice for a gas of impenetrable bosons in a tight atomic waveguide. We use an exact solution, which is based on an equivalence between strongly interacting bosons and noninteraction fermions, in order to derive the exact quantum dynamical evolution. At long times, in the thermodynamic limit, we observe the approach to a nonequilibrium steady state, characterized by the absence of quasi-long-range order and a reduced visibility in the momentum distribution. Similar features are found in a finite-size system at times corresponding to half the revival time, where we find that the system approaches a quasisteady state with a power-law behavior.In the second part, we study the effect of additional dipolar interactions on the ground state of the system. The inclusion of dipole-dipole interaction leads to new quantum phases of the one-dimensional system, but can also lead to a transverse instability.This instability is first analyzed in the classical regime. We study classical particles with dipolar interactions, that are confined on a chain by a harmonic potential. The dipoles are polarised perpendicular to the plane of confinement. Classical particles with repulsive power-law interactions undergo a transition from a single to a double chain (zigzag) by decreasing the confinement in the transverse direction. We theoretically characterize this transition when the particles are classical dipoles, polarized perpendicularly to the plane in which the motion occurs, and argue that this transition is of first order, even though weakly. The nature of the transition is determined by the coupling between transverse and axial modes of the chain and contrasts with the behavior found in Coulomb systems, where the linear-zigzag transition is continuous and belongs to the universality class of the ferromagnetic transition. Our results hold for classical dipolar systems and Rydberg atoms, which can offer a test bed for simulating the critical behavior of magnets with lattice coupling.In the quantum regime, we consider dipolar bosons in an optical lattice, tightly confined by an anisotropic harmonic potential. In the regime where a single chain becomes unstable, we show that the system can be mapped onto an extended multi-mode Bose-Hubbard model, where the coefficients can be determined by means of a low energy theory. A path integral Monte Carlo method, exact diagonalization and TEBD are used to determine the ground state of the extended Bose-Hubbard models. and show that the model captures the linear to zigzag transition
Chung, Brice. "Régime fortement corrélé dans des atomes ultra froids en rotation". Paris 11, 2009. http://www.theses.fr/2009PA112157.
Texto completoResearch in quantum gases is particularly active. Many of these atomic systems correspond to those coming from condensed matter physics. It is the case for rapidly rotating quantum gases which in some limit, is analogous to that of the quantum Hall effect. In this thesis, we analyze the strongly correlated regime reached in rapid rotation. The richness of the quantum Hall physics is combined to the peculiarities of cold atomic gases (tunable interactions, bosonic and fermionic statistics, etc. ). In particular, we show the formation of a Fermi sea out of a bosonic gas in dipolar interaction. The case of its instability by formation of Cooper pairs is discussed (Moore-Read state). Correlations on spherical geometry by use of density-density correlations are being analyzed. Finally, we address by the Hamiltonian formalism developed by R. Shankar and G. Murthy, the gap calculation at the principal fraction nu=1/2 for bosons with dipolar interactions and discuss about contradicting results
Reymond, Georges-Olivier. "Etudes expérimentales d'atomes dans un piège dipolaire microscopique". Phd thesis, Université Paris Sud - Paris XI, 2002. http://tel.archives-ouvertes.fr/tel-00002178.
Texto completoDarquié, Benoît. "MANIPULATION D'ATOMES DANS DES PIÈGES DIPOLAIRES MICROSCOPIQUES ET ÉMISSION CONTRÔLÉE DE PHOTONS PAR UN ATOME UNIQUE". Phd thesis, Université Paris Sud - Paris XI, 2005. http://tel.archives-ouvertes.fr/tel-00011604.
Texto completoNous avons caractérisé la géométrie du potentiel et le mouvement des atomes piégés par des mesures de fréquences d'oscillation et d'énergies moyennes.
Pour prouver que ce système est adapté au traitement quantique de l'information, nous montrons que son extensibilité à grande échelle est envisageable. A l'aide d'un modulateur de phase programmable par ordinateur et à partir d'un seul faisceau laser, nous avons généré holographiquement des réseaux de micro-pièges dipolaires pour atomes uniques, chacun des sites étant adressable individuellement.
En vue de réaliser des portes logiques à deux bits quantiques, nous avons choisi de nous orienter vers leur intrication conditionnelle. Celle-ci passe par le contrôle de l'émission de l'atome à l'échelle du photon unique, obtenue à la suite d'une excitation impulsionnelle. Nous avons conçu une chaîne laser délivrant des impulsions nanosecondes. Elle nous assure un contrôle cohérent de la transition fermée (5S1/2, F = 2, mF = 2) vers (5P3/2, F = 3, mF = 3). Nous avons observé des oscillations de Rabi et des battements quantiques sur des atomes uniques. En ajustant la puissance de la chaîne laser pour réaliser des impulsions pi, on obtient une source déclenchable de photons uniques qui présente un flux de hotons important et un faible taux d'impulsions contenant deux photons.
Darquié, Benoît. "Manipulation d'atomes dans des pièges dipolaires microscopiques et émission contrôlée de photons par une atome unique". Paris 11, 2005. https://pastel.archives-ouvertes.fr/tel-00011604.
Texto completoThis work deals with the manipulation of single atoms of rubidium 87 in microscopic optical dipole traps, in order to use them for quantum information processing. The experimental setup is based on a high numerical aperture lens which allows us to focus a beam to the diffraction limit and collects the light emitted by the atoms with a high efficiency. We have characterized the geometry of the potential and the movement of the trapped atoms by measuring oscillation frequencies, and mean energies of the atoms. To demonstrate that our setup is well suited to quantum information processing, we prove its scalability. Using a programmable phase modulator and holographic techniques, we have generated, from a single beam, arrays of micro-dipole traps, each of them being optically addressable. In order to realize two qubit logic gates, we have decided to go towards conditional entanglement. This requires the controlled emission of single photons by each of the atoms, which is obtained after a pulsed excitation. We have developed a new laser system delivering pulses of 4 ns every 200 ns, with a peak power from 1 to 10 W. It allows us to drive coherently the closed transition 5S1/2,F=2,mF=±2 to 5P3/2,F=3,mF=±3. We then observed Rabi oscillations and quantum beats with single atoms. By adjusting the power of the laser source to realize pi-pulses, we obtain a triggered single photon source with a high flux of photons and a weak rate of pulses containing two photons
Rabault, Martin. "Condensation de Bose-Einstein tout-optique en microgravité pour l'interférométrie atomique". Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0193/document.
Texto completoThe I.C.E experiment aims at testing the weak equivalence principle (WEP) underlying Einstein’s theory of general relativity and which postulates the equivalence between inertial mass and gravitationnal mass. If this principle has always been verified until today, it is of fundamental interest for physics to continue the measurements with greater precision. Indeed, new unifying theories of quantum mechanics and general relativity predict a violation of this principle. To carry out a test of the WEP, it suffices to compare the accelerations of two objects in free fall in the same gravitationnal field. This is what the I.C.E experiment, on the quantum scale, achieves (unlike the spatial Microscope mission, which to date has been able to verify the principle of equivalence with macroscopic objects with a sensitivity on of 2.10−14). Thus, the experiment consists in performing, by an interferometric method, the measurement of the acceleration of two atomic species (87Rb and 39K) of different mass and composition in free fall in a vacuum chamber. The measurement sensitivity of the inertial effects to which the atoms are sensitive (accelerations and rotations) is all the greater as the free fall time of the atoms is high and their temperature is low. But on Earth, in the laboratory, the atoms eventually fall to the bottom of the vacuum chamber containing them under the effect of gravity, which greatly limits the measurement sensitivity achievable. This is why it is interesting to place the experiment in a microgravity environment in which the atoms stay in the center of the vacuum chamber in order to reach much longer interrogation times. As such, several times a year, the experiment is put aboard the aircraft Zero-g of the Novespace company. The available microgravity durations make it possible to reach theoretical interrogation times of the order of one second, which should raise the sensitivity level to 10−11. However, we are today very strongly limited by the high level of vibrations of the aircraft as well as its rotations : the loss of contrast of the interference fringes and the phase noise caused, do not allow us to exceed 5 ms of interrogation times in 0 g. Since the coherence of an atomic source is directly related to its temperature, the use of ultra-cold clouds is of great interest to improve the contrast of the interference fringes, especially for the long interrogation times targeted. In parallel, the laboratory is now equipped with a microgravity simulator on which is mounted the experiment, giving access to interrogation times of more than 250 ms with parabolic trajectories of a very good repeatability (of the order of 3 mg). This manuscript synthesizes the work that produced the very first 87Rb Bose-Einstein condensate in microgravity by all-optical methods, with a repetition rate of 13,5 seconds. We demonstrate the efficiency of our dipole trap loading method based on the association of a grey molasses cooling and a spatial modulation of the dipole beams. These results pave the way for future highly sensitive interferometric measurements with a large scale factor
Gouraud, Baptiste. "Optical nanofibers interfacing cold toms. A tool for quantum optics". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066026/document.
Texto completoWe built a new experiment using cold atoms interacting with the light guided by an optical nanofiber. We first developed a nanofiber manufacturing bench. By heating and stretching a commercial optical fiber, a silica cylinder of 400 nm diameter is obtained. The light guided in these nanofibers is strongly focused over the whole length and exhibits strong evanescent fields. We then prepared a vacuum chamber and the laser system necessary for the manipulation of cold atoms. After inserting a nanofiber amid a cloud of cold atoms, we observed the phenomenon of slow light under the conditions of electromagnetically induced transparency: the light guided by the fiber is slowed down to a speed 3000 times smaller than its usual speed. We also stored the light guided by an optical fiber. After several microseconds, the information stored as a collective atomic excitation could be retrieved in the fiber. We have shown that this optical memory works for light pulses containing less than one photon on average. This system may therefore be used as a quantum memory, an essential tool for future quantum communication networks. Finally, we trapped atoms in an array in the vicinity of the nanofiber thanks to the light guided by the latter. Compared to our first set of experiments, the resulting cloud has a longer lifetime (25 ms) and interacts more strongly with the guided light (OD ~ 100). This new system should allow to efficiently implement other quantum optics protocols, such as the generation of single photons, or the entanglement of two remote atomic ensembles
Dugué, Julien. "Sources Ultrafroides Avancées pour l'Interféromètrie et la Physique Atomiques". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00410953.
Texto completoHyafil, Philippe. "VERS LE PIEGEAGE D'ATOMES DE RYDBERG CIRCULAIRES". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2005. http://tel.archives-ouvertes.fr/tel-00012092.
Texto completoentrepris la construction d'un dispositif expérimental visant à piéger des atomes de Rydberg circulaires au voisinage d'éléments micro-fabriqués en surface d'une puce. La source primaire de Rubidium est un jet atomique vertical fournissant un flux d'atomes
lents. Nous démontrons la possibilité de réaliser la séquence expérimentale suivante. Les atomes sont tout d'abord recapturés à l'intérieur d'un cryostat à Hélium pompé au sein duquel a lieu la suite des manipulations. L'utilisation de techniques de
micro-piégeage atomique à la surface d'une puce permet ensuite la préparation d'un nuage froid et dense de Rubidium. Après un processus d'excitation composé de plusieurs échelons lasers et radiofréquences on obtient un atome de Rydberg circulaire unique grâce au phénomène de blocage dipolaire. Cet atome est finalement confiné dans un piège électrique dynamique tirant parti de l'extrême
polarisabilité des états atomiques utilisés. Une technique « d'habillage micro-onde » réduit la différence de polarisabilité entre deux niveaux donnés, autorisant ainsi le maintien d'une
cohérence quantique sur un temps de l'ordre de la seconde. Le temps de vie atomique est également prolongé grâce à l'inhibition de l'émission spontanée due à la proximité de surfaces métalliques. En
dernier lieu, la mesure de l'état atomique final après interaction est effectuée en détectant l'électron d'ionisation grâce à un compteur supraconducteur.
Emmert, Andreas. "Puce à atomes supraconductrice : atomes à froids dans un environnement cryogénique et excitation d'atomes de Rydberg". Paris 6, 2009. http://www.theses.fr/2009PA066637.
Texto completoAtom-chips are a versatile tool for the manipulation of cold atoms with magnetic potentials created by microstructures. However, one observes significant atom losses in those traps caused by spin-flip transitions, induced by radio-frequency fluctuations of the magnetic field, when the atoms are close to the chip surface. These fluctuations are due to Johnson-Nyquist noise in metallic structures. In our setup, the lifetime of atoms far away from the chip in a cryogenic environment is very long due to a low residual pressure obtained by cryogenic pumping. At a distance of several tens of micrometers yet, the lifetime is still limited by Johnson-Nyquist noise. One solution to this problem is the use of a purely superconducting environment, even in the realistic case of an atom-chip made of a type II superconductor containing vortices. We observe that the superconducting film influences the trapping potential, demonstrating the presence of micrometer size permanent supercurrents. We are able to induce these currents on demand with the potentiality to create complex traps. A cryogenic atom-chip can also be used for trapping strongly excited atoms (Rydberg atoms) which have a huge transition dipole moment that could be coupled to mesoscopic solid-state quantum systems. This long-term goal in mind, we have adapted our experiment for the excitation of Rydberg atoms. First excitation spectra reveal a parasitic electric field in the close vicinity of the atom-chip which is sufficiently weak for the next step of our experiment, the excitation of an single atom on demand using the dipole blockade effect
Karcher, Romain. "Implémentation d'une source d'atomes ultra-froids pour l'amélioration de l'exactitude d'un gravimètre atomique Improving the accuracy of atom interferometers with ultracold sources A determination of the Planck constant using the LNE Kibble balance in air". Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS165.
Texto completoThis thesis aims to improve the accuracy of the Cold Atom Gravimeter from LNESYRTE.This gravimeter employs atom interferometry techniques to measure the local gravityacceleration g of free falling Rubidium 87 cold atoms. This gravimeter is the national metrologicalreference meaning that all its biases must be evaluated with the lowest uncertainties. At the beginningof this thesis, the total accuracy budget of 4.3μGal was dominated by the uncertainty onthe wavefront aberration bias which accounted for 4.0μGal. In order to improve the evaluation ofthis effect, we implemented an ultra-cold atom source, with which we performed g measurementsover a wide range of temperatures. The developpment of a complete model of the experiment anda simulation of the impact of the wavefronts on the g measurements allowed us to gain insightson the evaluation of this bias which uncertainty was thus improved by a factor three and is now1.3μGal. Finally the gravimeter participated in the Kibble balance project which goal was tolink the Planck constant to the kg unit. This project needed the determination and transfer ofthe absolute g value. We contributed to the revolution of the International System of Units : thePlanck constant is now fixed and the definition of the kg is modified. This new definition is noweffective since 20 May 2019
Couvert, Antoine. "Production et étude de lasers à atomes guidés, et de leur interaction avec des défauts contrôlés". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00442294.
Texto completoChotia, Amodsen. "Dynamique de l'interaction dans un gaz d'atomes de Rydberg froids. Blocage dipolaire, ionisation Penning. Pompage optique et refroidissement de la vibration de molécules". Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00447969.
Texto completoVogt, Thibault. "Blocage dipolaire de l'excitation d'atomes froids vers des états de Rydberg : contrôle par champ électrique et résonance de Förster". Paris 11, 2006. https://tel.archives-ouvertes.fr/tel-00135180.
Texto completoChandra, Aveek. "Coupling 1D atom arrays to an optical nanofiber : Demonstration of an efficient Bragg atomic mirror". Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066582/document.
Texto completoThe coupling of cold atoms to 1D nanoscale waveguides have opened new avenues of research. The waveguide in our case is a nanofiber, which confines light transversally to a subwavelength scale. The guided light exhibits a strong evanescent field allowing enhanced atom-photon interaction in the vicinity of nanofiber. In our experiment, a cold atomic cloud is first interfaced with an optical nanofiber. By using an optical lattice in the evanescent field, the atoms are then trapped in 1D atomic arrays close to the nanofiber. In this platform, we reach high optical depth OD ~ 100 and long lifetimes ~ 25 ms by using a dual-color compensated trapping scheme that preserves the internal properties of atoms. In this thesis, we explore collective effects emerging from the spatial ordering of atoms. When the period of the lattice is made close to commensurate with the resonant wavelength, Bragg reflection, as high as 75%, is observed. The reflection shows dependency on orientation of the probe polarization relative to the atomic arrays - a chiral signature in nanoscale waveguide-QED systems. The ability to control photon transport in 1D waveguides coupled to spin systems would enable novel quantum networking capabilities and the study of many-body effects arising from long-range interactions
Mestre, Michael. "Holographie dynamique appliquée aux atomes froids : cas du guidage dans un mode laser de Laguerre-Gauss". Paris 11, 2008. http://www.theses.fr/2008PA112359.
Texto completoThe use of a spatial light modulator (SLM), a reconfigurable diffractive element, was studied in the context of cold atom experiments. The SLM enabled to shape an infrared laser beam by far-field diffraction, creating a dipole potential in a magneto-optical trap (MOT) for Rubidium atoms. A detailed study of the numerical algorithms designed to compute holograms for creating arbitrary diffraction patterns has been performed, and the fundamental and technical hurdles preventing the production of smooth patterns have been identified. The use of analytically known holograms was also studied, with an emphasis on the holograms that create a phase dislocation in the center of the beam. Ring shaped Laguerre-Gaussian beams have been produced using this method. The absence of light intensity in the center of such beams enables one to obtain a dipole guide for the cold atoms, in which the atoms are trapped in a region where the rate of spontaneous emission is a local minimum. A quantitative evaluation of the cold atom guiding efficiencies as a function of various parameters has been performed (frequency detuning and radial order of the Laguerre-Gaussian beam, by taking advantage of the dynarnic reconfiguration capabilities of the SLM). Ln parallel, a quick switching technique for the SLM, based on acousto-optic modulators, was developed to provide the means to modify a dipole potential in a few microseconds in an atomic physics experiment
Kadio, Demascoth. "Réalisation expérimentale et étude d'un guide pour atomes froids d'une séparatrice et d'un miroir concave". Paris 11, 2002. http://www.theses.fr/2002PA112082.
Texto completoWe have realized and demonstrated three efficients atom optics elements: a guide and a beamsplitter which use the dipole force and a concave mirror which uses the magnetic force. These elements have been tested with a cold atoms 87-Rb cloud at a temperature of 10 mK in an optical molasses. The guide is realized with a far red-detuned Nd:YAG laser beam which creates a 2-D dipole trap. When the atomic cloud is released from the optical molasses, it falls due to gravity and due to the dipole guide the atoms remain localised inside the guiding laser beam. The guide efficiency is about 40% over a distance of 30 cm. Furthermore, as the laser beam is focused an adiabatic compression of the cloud occurs, and in a defocusing region of the laser beam, its adiabatic cooling is observed to 2 mK, corresponding to a factor 5 between the temperature of the cloud in the molasses [1]. The results are numerically interpreted, by using a Monte Carlo statistic method. We have observed in the guide experiment and have demonstrated by calcu1ation that if the atoms enter in the guide with a kinetic moment and if the guide is pulsed, we generate a doughnut clouds. The beamsplitter uses two crossing dipole guides: one is along the vertical axis et the other along an oblique direction making a 0. 12 radian angle with the vertical. The atoms are first guided in the vertical one. When they have travelled a few millimeters the second guide is suddenly switched on. The created coupling at the crossing point of the two guides allows an atom transfer from the vertical to the oblique direction. The observation, 10 mm below the initial trap position, shows a cloud splitting ranging a few millimeters. The measured transfer efficiency is about 30% [2]. We have demonstrated numerically that time control of the switching time of the oblique guide could permit to increase a larger beamsplitter efficiency. The concave mirror uses a pulsed magnetic quadrupole field, applied when the atoms are fallen a few millimeters. We have clearly observed two bounces. The magnetic potential is curved and the atoms bounce and simultaneously are refocused [3]. Nevertheless, this mirror is not perfect and presents some aberrations. We have shown by using a Monte Carlo statistic method that an addition time orbiting magnetic field would significant1y reduce the aberrations of the mirror. [1] L. Provost, D. Marescaux, O. Houde, H. T. Duong, Opt. Comm. 166 (1999) 199. [2] O. Houde, D. Kadio, L. Pruvost, Phys. Rev. Lett. 85 (2000) 5543. [3] D. Kadio, O. Houde, L. Provost, Euro. Phys. Lett. 54 (2001) 417
Hyafil, Philippe. "Vers le piègeage d'atomes de Rydberg circulaires". Paris 6, 2005. https://tel.archives-ouvertes.fr/tel-00012092.
Texto completoDe, paz Aurelie. "Échange de spin et dynamique d’aimantation d’un gaz quantique dipolaire". Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCD096/document.
Texto completoThis Thesis reports on several experimental studies of magnetic properties of a Chromium Bose-Einsteincondensate loaded into a 3D optical lattice, focusing on the effects induced by dipolar interactions.We show that in a 3D lattice dipolar relaxation is a resonant process due to the reduction of the density ofaccessible orbital states. These resonances are observed for magnetic fields Bres such that the Zeeman energyreleased matches an excitation towards higher-energy bands of the lattice. We can thus inhibit those processes byapplying a field different from Bres. Analyses of the resonances allowed us to probe the lattice 3D band structureas well as to demonstrate the effects of local interactions between atoms.We study spin exchange dynamics in a 3D lattice. We especially observed for the first time spin exchangebetween atoms localized in different lattice sites mediated by dipolar interactions. These studies are the firststep toward a new exploration of magnetism in lattice. Varying the depth of the lattice we study these effects inthe superfluid regime, well described by mean filed theories, as well as in the strongly correlated regime, whosetheoretical description is still challenging.Finally, we study the evolution dynamics of two giant spins interacting through dipolar interactions. Thecondensate being initially splitted in half, atoms from the two clouds are prepared in opposite spin states thusproducing two giant spins ±3×N. We show that any spin dynamics is energetically inhibited for large spinswhich is well accounted for by a classical theory
Gaaloul, Naceur. "Étude théorique de la manipulation laser d'atomes froids". Paris 11, 2007. http://www.theses.fr/2007PA112339.
Texto completoThe topic of this thesis is the theoretical study of the laser manipulation of cold atomic ensembles. The purpose is to improve the control over external degrees of freedom and to propose new schemes of atom optics. The first step consists in modelizing an experiment of a cold atoms beam-splitter working in the gravitational field. The evolution of the atomic populations in the time-dependant light potentials is obtained by solving the Schrodinger equation. This resolution is performed by a temporal propagation of translational wave-packets. Improvements of the efficiency of the beam-splitter are proposed as well as a scheme of a coId atoms deflector functioning in a free fall configuration. The model was then extended to the case of Bose-Einstein condensates. The dynamics of the system is then governed by the Gross-Pitaevskii equation and its resolution gives access to the evolution of the condensate wave function. A quantum degenerate gases deflector is proposed and its characteristics are explored within realistic conditions. The last part of the thesis deals with the study of Bose-Einstein condensation in light potentials shaped by spatial light modulators (SLM). The specificities of these potentials are studied and compared with harmonic potentials normally used in condensation experiments. This study is based on realistic experimental data and emphasizes the interest in using such systems to obtain and manipulate quantum degenerate gases
Mimoun, Emmanuel. "Condensat de Bose-Einstein de sodium dans un piège mésoscopique". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00527457.
Texto completoJelassi, 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". Paris 11, 2007. http://www.theses.fr/2007PA112143.
Texto completoThis thesis is composed of two parts. The first part presents the study of the realization of a lens for atoms using the dipolar interaction. A theoretical study suggests several possible experimental sequences allowing the realization of an achromatic lens with a controllable magnification. Attempts at realizing the sequence highlighted atom losses induced by the laser. The process of photoassociation, strongly probable under the experimental conditions, is responsible of the losses. The second part of this thesis reports on the recording of the photoassociation spectra. The analysis of the spectra obtained was carried out using the Lu-Fano graphs methods, which is often used in the physics of Rydberg atomic states. Applied to the three observed vibrational series, the method showed that the LeRoy-Bernstein formula established to describe vibrational levels located in the asymptotic zone of the molecular potential, must be improved. The two suggested improvements consist in taking into account the short-range region of the potential well and the second term of the multipolar expansion. For a third series, the Lu-Fano graph exhibits a coupling between two vibrational series due to the spin-orbit and spin-spin interactions. The graph allowed a quantitative characterization of this coupling
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.
Texto completoPerrin, Hélène. "Condensats de Bose-Einstein, champs évanescents et champs radio-fréquences". Habilitation à diriger des recherches, Université Paris-Nord - Paris XIII, 2008. http://tel.archives-ouvertes.fr/tel-00355511.
Texto completoDans un second temps, sur la proposition d'Oliver Zobay et Barry Garraway, nous avons mis au point une nouvelle approche pour confiner les atomes dans des potentiels très anisotropes. La combinaison d'un champ radiofréquence (RF) et d'un champ magnétique statique résulte en un potentiel adiabatique dont la géométrie peut être largement contrôlée, y compris dynamiquement. Ces potentiels RF permettent de réaliser une « bulle » à atomes, un double puits, un anneau... Nous nous sommes intéressés principalement à produire un piège quasi bidimensionnel dans l'épaisseur de la bulle. Ces pièges sont compatibles avec les condensats de Bose-Einstein, et les atomes peuvent être refroidis par évaporation in situ. Nos premières expériences impliquant des champs radiofréquence ont eu un impact important dans la communauté des atomes froids, en particulier pour les expériences sur puce. A la suite de nos travaux, de nombreuses équipes ont utilisé cette technique avec succès.
Bouchoule, Isabelle. "Refroidissement par bandes latérales d'atomes de Césium et quelques applications". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2000. http://tel.archives-ouvertes.fr/tel-00011771.
Texto completoMorice, Olivier. "Atomes refroidis par laser : du refroidissement sub-recul à la recherche d'effets quantiques collectifs". Phd thesis, Université Pierre et Marie Curie - Paris VI, 1995. http://tel.archives-ouvertes.fr/tel-00011902.
Texto completoPasquiou, Benjamin. "Effets de l'interaction dipôle-dipôle sur les propriétés magnétiques d'un condensat de chrome". Phd thesis, Université Paris-Nord - Paris XIII, 2011. http://tel.archives-ouvertes.fr/tel-00659391.
Texto completoLandragin, Arnaud. "Réflexion d'atomes sur un miroir à onde évanescente : Mesure de la force de van der Waals et diffraction atomique". Phd thesis, Université Paris Sud - Paris XI, 1997. http://tel.archives-ouvertes.fr/tel-00400765.
Texto completoLeseleuc, de kerouara Sylvain de. "Quantum simulation of spin models with assembled arrays of Rydberg atoms". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLO007.
Texto completoSingle atoms trapped in arrays of optical tweezers and excited to Rydberg states are a promising experimental platform for the quantum simulation of spin models. In this thesis, we first solved a long-standing challenge to this approach caused by the random loading of the traps, with only 50% of them filled with single atoms. We have engineered a robust and easy-to-use method to assemble perfectly filled two-dimensional arrays of 87Rb atoms by moving them one by one with a moveable optical tweezers controlled by computer, a technique further enhanced to trap, image and assemble three-dimensional arrays. We then implemented the quantum Ising model by coherently coupling ground-state atoms to a Rydberg level. After finding experimental parameters where the dipole-dipole interaction takes the ideal form of a van der Waals shift, we performed adiabatic preparation of the Néel state. We showed that the coherence time of our excitation lasers limited the efficiency of this technique. We then used a different type of interaction, a resonant dipolar coupling, to implement XY spin models and notably the Su-Schrieffer-Heeger model, known for its fermionic topological phase protected by the chiral symmetry. Here, we used effective hard-core bosons, which modify the properties of the topological phase. We first recovered known properties at the single particle level, such as the existence of localized zero-energy edge-states. Then, preparing the many-body ground state at half-filling, we observed a surprising robustness of its four-fold degeneracy upon applying a perturbation. This result was explained by the existence of a more general symmetry protecting the bosonic phase
Hoang, Nathalie. "Développement d'un piège atomique lumineux et magnétique : étude du régime de collisions : perspectives pour la condensation de Bose-Einstein du césium". Paris 11, 2003. https://tel.archives-ouvertes.fr/tel-00005990.
Texto completoThis thesis work is part of a research effort made since 1996 in the field of the Bose-Einstein condensation (BEC) of cesium atoms. The first attempts carried out in 1996 using magnetic trapping and rf evaporative cooling failed because of the unusually high inelastic collision rates encountered by this atom. The solution consists in trapping the atoms in the lowest energy state. This can be performed in an optical trap or in a hybrid trap, both magnetic and optical. Recently R. Grimm's group demonstrated cesium BEC with an optical trap. The solution discussed in this work combines a vertical magnetic trap and a transversal optical trap created by a laser beam Nd: YAG. The experimental apparatus has been completed, and the hybrid trap has been partly characterized. The 4 s lifetime is the current limitation of the trap and is discussed on the basis of some assumptions. The collisionnal dynamics are analysed from the atomic cloud oscillations while varying the magnetic field. Actually, the elastic collision rate of the atoms inside the trap is low, because of a low density. In the same time, numerical calculations have been performed. This theoretical work has two parts. The first one consists in a Monte-Carlo simulation of one dimension evaporative cooling in our set-up. These results figure out the direction we should follow towards BEC. The second part relies on the application of an asymptotic method for studying collisions in a magnetic field between two atoms in their ground state f=3, mf=3. This study motivated by the existence of a Feshbach resonance for this state allows the interpretation of a photoassociation experiment. In this experiment, the tunability of the scattering length with respect of the magnetic field has been observed
Kermaidic, Yoann. "Mesure du moment dipolaire électrique du neutron : analyse de données et développement autour du ¹⁹⁹Hg". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY055/document.
Texto completoA permanent electric dipole moment (EDM) is a fundamental property of simple systems such as the electron, atoms/molecules or the neutron whose amplitude is expected to be non-zero within the Standard Model of particles physics (SM) but which has never been observed so far. This observable violating the CP symmetry offers the opportunity to link particle physics to the fundamental cosmological enigma of the observed baryon asymmetry of the Universe. Such an asymmetry requires new CP violation sources/mechanism beyond the SM, which can be best probed by EDM searches. The current EDM experiments sensitivity is order of magnitude above the weak SM sector predictions. Measuring a null EDM, after a 60 years quest, set the strongest upper limit on the CP violation in the strong SM sector and constrains the new physics models phase space. On the contrary, measuring a non-zero EDM in the coming years can be understood as a signal from physics beyond the SM evolving at a multi-TeV scale. In this haunting perspective, many new EDM projects raised in the last years and important efforts are pursued near the neutron in particular. This manuscript present the neutron EDM search near the most sensitive experiment running at the Paul Scherrer Institute in Switzerland
Fuhrmanek, Andreas. "From single to many atoms in a microscopic optical dipole trap". Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00655970.
Texto completoDiry, Fabienne. "Holographie dynamique pour les atomes froids : modes de Laguerre-Gauss et leurs variantes". Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00642811.
Texto completoRoccia, Stéphanie. "La co-magnétométrie mercure pour la mesure du moment électrique dipolaire du neutron : optimisation et application au test de l'invariance de Lorentz". Grenoble 1, 2009. https://theses.hal.science/tel-00440287.
Texto completoIn this thesis, magnetometry is studied in the context of the neutron Electric Dipole Moment (nEDM) measurement with the RAL/Sussex/ILL spectrometer. In particular, the pre-existing mercury co-magnetometer has been modeled and optimized to be used in the next nEDM measurement at the Paul Scherrer Institut (Villigen Suisserland) in 2010-2012. Using data taken at the Institut Laue-Langevin (Grenoble, France), the complementarity between external cesium magnetometry and mercury co-magnetometry has been studied, bringing two results : - a best way to control systematics due to the co-magnetometer - a limit on the neutron anomalous couplings that violates Lorentz invariance
Jacob, David. "Condensats de Bose-Einstein de spin 1 : étude expérimentale avec des atomes de sodium dans un piège optique". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00730750.
Texto completoRaskop, Jérémy. "Quantum optics with single collective excitations of nanofiber-trapped arrays of atoms". Thesis, Sorbonne université, 2020. http://www.theses.fr/2020SORUS005.
Texto completoThis thesis focuses on the study of interactions between photons guided by an optical nanofiber and arrays of trapped atoms. Our experimental setup consists in a two-color compensated dipole trap located in the evanescent field of an optical nanofiber in a ultra-high vacuum chamber. Cold cesium atoms are trapped in two 1D arrays above and below the nanofiber. An optical depth of over 130 is achieved with only a few thousand atoms. We demonstrate the ability to prepare the trapped atoms in a single Zeeman sub-level, albeit with limited efficiency. This is an important step towards the realization of a long-lived quantum memory with our fibered platform. The main result of this thesis concerns the initialization of a single collective excitation coupled to the nano-waveguide. The excitation is heralded by the detection of a Raman scattered photon in the nanofiber. We are then able to readout the atomic state and retrieve a single photon in the guided mode with an efficiency of up to 25%. This result is the first demonstration of an atomic entangled state preferentially coupled to a waveguide. It is a milestone in the context of the emerging waveguide-QED approach, with applications to quantum networking, quantum non-linear optics and quantum many-body physics
Khalili, Guyve. "Réalisation d'une source d'électrons par ionisation d'un jet d'atomes de césium refroidis par laser". Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112103/document.
Texto completoElectron and Ion beams are at the base of many instrumental techniques used to explore, to analyse and to modify materials from the micrometer to the manometer scale (Electronic Microscopy, Electron Spectrometry, Focused Ion beams techniques…). Spatial and Energetic resolutions of these techniques are strongly dependent on its source‘s properties and particularly their working temperature. In fact, for more than ten years, the potential of ionised cold atoms have been intensively studied. Our experiment at LAC, described in this thesis, uses a 2 dimensional magneto-optical trap (2D-MOT) to create a caesium atomic beam. The transverse temperature of the beam is around 100 µK. Despite this, the beam is still too divergent after exiting the cooling area. To guide the atomic beam up to the ionisation area, we have studied and implemented a particular method of dipolar guiding. The use of a unique laser properly set allowed us to push and guide altogether the atoms of the beam while limiting the heating effect. Thus, we have managed to compress the atomic beam’s size to 400 µm at 60 cm from the output of the MOT.Afterward, the atomic beam is ionised by the method of Rydberg (static) field ionisation. The atoms are firstly excited by laser on a Rydberg state (n~30) as a static homogeneous and uniform electric field is applied. The excited atoms of beam travel therefore to a high-gradient field area where they ionise around the same electric potential value, therefore reducing the ionisation area’s size and the initial potential energy spread of the electron beam. The ionisation probability of the atoms in the field depends greatly on the excited Rydberg state. The choice of an optimal Rydberg state , i.e. with the highest probability of ionisation, needs better knowledge of the ionisation of cesium Rydberg states. A two levels model us to describe the ionisation behaviour of some Ryberg. This simple models helps to understand what kind of states we want to excite in order to optimise the ionisation area‘s size. An experimental study of cesium Rydberg states is also presented
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.
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