Decoherence due to photon scattering in an atom interferometer was studied as a function of laser frequency near an atomic resonance. The resulting decoherence (contrast-loss) spectra will be used to calibrate measurements of tune-out wavelengths that are made with the same apparatus. To support this goal, a theoretical model of decoherence spectroscopy is presented here along with experimental tests of this model.

An atom interferometer is a sensitive device that has potential for many useful applications. Atoms are sensitive to electromagnetic fields due to their electric and magnetic moments and their mass allows them to be deflected in a gravitational field, thereby making them attractive for measuring inertial forces. The narrow momentum distribution of Bose-Einstein condensate (BEC) is a great asset in realizing portable atom interferometers. An example is a guided-wave atom interferometer that uses a confining potential to guide the motion of the condensate. Despite the promise of guided-wave atom interferometry with BEC, spatial phase and phase diffusion limit the contrast of the interference fringes. The control of these phases is required for successful development of a BEC-based guided-wave atom interferometer. This thesis analyses the guided-wave atom interferometer, where an atomic BEC cloud at the center of a confining potential is split into two clouds that move along different arms of the interferometer. The clouds accumulate relative phase due to the environment, spatially inhomogeneous trapping potential and atom-atom interactions within the condensate. At the end of the interferometric cycle, the clouds are recombined producing a cloud at rest and moving clouds. The number of atoms in the clouds that emerge depends on the relative phase accumulated by the clouds during propagation. This is investigated by deriving an expression for the probability of finding any given number of atoms in the clouds that emerge after recombination. Characteristic features like mean, standard deviation and cross-correlation function of the probability density distribution are calculated and the contrast of the interference fringes is optimized. This thesis found that optimum contrast is achieved through the control of total population of atoms in the condensate, trap frequencies, s-wave scattering length, and the duration of the interferometric cycle.

This Dissertation describes how I used a three nanograting Mach-Zehnder atom beam interferometer to precisely measure a wavelength of light, known as a tune-out wavelength, that causes zero energy shift for an atom. I also describe how such measurements can be remarkably sensitive to rotation rates. It is well known that atom interferometry can be used to measure accelerations and rotations, but it was a surprise to find out that tune-out wavelength measurements can under certain conditions be used to report the absolute rotation rate of the laboratory with respect to an inertial frame of reference. I also describe how we created conditions which improve the accuracy of tune out wavelength measurements. These measurements are important because they serve as a benchmark test for atomic structure calculations of line strengths, oscillator strengths, and dipole matrix elements. I present a new measurement of the longest tune-out wavelength in potassium, λzero = 768.9701(4) nm. To reach sub-picometer precision, an optical cavity surrounding the atom beam paths of the interferometer was used. Although this improved the precision of our experiment by increasing the light-induced phase shifts, the cavity also brought several systematic errors to our attentions. For example, I found that large ±200 pm shifts in tune-out wavelengths can occur due to the Earth's rotation rate. To solve this problem, I demonstrated that controlling the optical polarization, the magnetic field, and the atom beam velocity distribution can either suppress or enhance these systematic shifts. Suppressing these systemic shifts in tune-out wavelengths is useful for precision measurements used to test atomic structure calculations. By enhancing these systematic shifts, the interferometer can be a gyroscope that utilizes tune-out wavelengths.

Atomic polarizability plays an essential role in topics ranging from van der Waals interactions, state lifetimes, and indices of refraction, to next generation atomic clocks and atomic parity non-conservation experiments. Polarizability measurements, such as the ones described in this thesis, provide valuable input to these subjects and serve as benchmark tests for sophisticated atomic structure calculations. We measured the static polarizability of potassium and rubidium with record precision and 0.5% uncertainty using a Mach-Zehnder atom interferometer with an electric-field gradient. To support future precision measurements of polarizability, we developed a new atom beam velocity measurement technique called phase choppers. Using phase choppers, we demonstrated measurements of mean atom beam velocity with an uncertainty of 0.1%. We also developed a new way to probe atomic structure: a measurement of a zero-crossing of the dynamic polarizability of potassium, known as a magic-zero wavelength. We measured the first magic-zero wavelength of potassium with 1.5 pm uncertainty and established a new benchmark measurement for the ratio of the D1 and D2 line strengths. Finally, we propose the use of a resonant photoionization detector for measurements of strontium polarizability, and the use of contrast interferometry for measurements of alkali dimer tensor polarizabilities.

This dissertation describes new measurements of the van der Waals (vdW) potential energy for atoms near a surface. The measurements presented here were accomplished by studying diffraction a beam of atoms transmitted through a nanograting. I will describe how we improved precision by a factor of 10 over previous diffraction measurements by studying how different types of atoms interact with the same surface. As a result of this new precision, we were able to show for the first time the contribution of atomic core electrons to the atom-surface potential, and experimentally test different atomic structure calculation methods.In addition, this dissertation will describe how changing the width of the grating bars to achieve a particular "magic" grating bar width or rotating a grating to a particular "magic" angle allows us to determine both the atom-surface potential strength and the geometry of the grating. This represents an improvement over several recent studies where uncertainties in the nanograting geometry limited precision in the measurements of the vdW potential.For a complementary measurement, also discussed in this dissertation, we collaborated with the Vigue group in Toulouse, France. In this collaboration we used an atom interferometer to measure the phase shift due to transmission through a nanograting. By combining diffraction data from Tucson with interferometry data from Toulouse we improved the precision of interferometry measurements of the atom-surface potential of a single atomic species by almost a factor of 10 over previous interferometric measurements of the vdW potential. These interferometry measurements also serve to measure the shape of the vdW potential and set a limit on non-Newtonian gravitational interactions at 1-2 nm length scales.Finally, this dissertation will discuss how nanogratings with optimized geometry can improve atom interferometers, for example, with blazed gratings. We discuss next generation atom-surface potential measurements and examine new ways of analyzing diffraction data.

We present revised measurements of the static electric dipole polarizabilities of K, Rb, and Cs based on atom interferometer experiments presented in [Phys. Rev. A 2015, 92, 052513] but now re-analyzed with new calibrations for the magnitude and geometry of the applied electric field gradient. The resulting polarizability values did not change, but the uncertainties were significantly reduced. Then, we interpret several measurements of alkali metal atomic polarizabilities in terms of atomic oscillator strengths f(ik), Einstein coefficients A(ik), state lifetimes tau(k), transition dipole matrix elements D-ik, line strengths S-ik, and van der Waals C-6 coefficients. Finally, we combine atom interferometer measurements of polarizabilities with independent measurements of lifetimes and C-6 values in order to quantify the residual contribution to polarizability due to all atomic transitions other than the principal ns-np(J) transitions for alkali metal atoms.

Après plusieurs décennies de développement, l'interférométrie atomique est devenue un outil extrêmement performant pour mesurer des effets inertiels, tels que des accélérations et des rotations. De telles techniques sont maintenant envisagées pour une future génération de détecteurs d'ondes gravitationnelles afin de pousser les limites de l'état de l'art des détecteurs actuels. L'instrument MIGA (Matter-wave laser Interferometer Gravitation Antenna) couplera interférométrie atomique et optique pour étudier des perturbations du champ gravitationnel à basse fréquence (Hz et sub-Hz). Il consistera en un réseau de 3 interféromètres atomiques, simultanément interrogés par le champ électromagnétique résonnant au sein de deux cavités optiques de 150 m de long, en utilisant un ensemble d'impulsions de Bragg d'ordre π/2 - π - π/2. Des mesures gradiométriques permettront d'acquérir une forte immunité aux bruits sismique et newtonien, qui sont limitants pour les détecteurs terrestres optiques tels que LIGO et Virgo. Une expérience préliminaire est en développement au LP2N, à Talence (France), où un interféromètre est interrogé par deux cavités de 80 cm de long. Pour avoir une taille de faisceau suffisante afin d'interroger efficacement les atomes de 87Rb dans des cavités de cette longueur, nous utilisons une géométrie de cavité marginalement stable, constituée de deux miroirs plans situés à la focale d'une lentille biconvexe, où un mode gaussien de rayon de plusieurs mm peut résonner. / After few decades of development, atom interferometry has become an extremely efficient tool for measuring inertial effects such as accelerations and rotations. Such techniques are now envisioned for a future generation of gravitational wave detectors to push further the limit of the current optical detectors. The Matter-Wave Laser Interferometer Gravitation Antenna (MIGA) instrument will couple atom and optical interferometry to study perturbations of the gravitational field at low-frequencies (Hz and sub-Hz). It will consist of an array of 3 atom interferometers, simultaneously interrogated by the light field resonating inside two 150 m long optical cavities, using a set of high order Bragg pulses π/2 - π - π/2. Gradiometric measurements allows a strong immunity to seismic and newtonian noises which limit optical ground-based detectors such as LIGO and Virgo. A preliminary experiment is being developed at the LP2N laboratory, in Talence (France), where a single atomic cloud is interrogated inside two 80 cm long cavities. In order to interrogate efficiently the 87Rb atoms, a gaussian beam with a radius of several mm resonating inside these cavities is required. This can be achieved by using a marginally stable cavity geometry, composed by two plane mirrors located in the focal planes of a biconvex lens.

L'interférométrie atomique a démontré sa capacité à effectuer des mesures de grande précision, notamment pour la réalisation de capteurs inertiels, les tests de physique fondamentale ou la mesure de constantes fondamentales. Une piste pour l'amélioration de la sensibilité des interféromètres atomiques est la réduction de la dispersion en vitesse de la source en utilisant un ensemble d'atomes ultra-froids pour augmenter le temps d'interrogation des atomes et accroitre la séparation spatiale entre les bras de l'interféromètre. Un nouvel interféromètre atomique à bras séparés est en construction au Laboratoire Collisions Agrégats et Réactivité de Toulouse. Ce dispositif répond à deux objectifs. Premièrement sa conception a pour but l'étude et le développement de nouveaux types de sources de condensat de Bose-Einstein (C.B.E.) double espèce de rubidium 85 et 87 adaptées à l'interférométrie. Cette source de C.B.E. repose sur l'utilisation de puces pour la manipulation et le refroidissement des atomes. Cette technologie est compacte et consomment peu d'énergie, ce qui est adaptée aux applications spatiales. L'autre objectif est d'utiliser cet interféromètre pour tester la neutralité de la matière via l'effet Aharonov-Bohm scalaire. Dans ce manuscrit je commence par exposer et justifer les choix techniques fait lors du dimensionnement et de la construction de la source de C.B.E. double isotopes. Par la suite, je présente les premiers résultats expérimentaux accompagnés de simulations numériques et d'explications théoriques. Lors de la première étape de refroidissement laser nous produisons un nuage de rubidium 87 et 85 contenant 4 × 10^10 atomes à une température de 10 µK avec un taux de cycle de 1 s. A la suite du refroidissement laser 8 × 10^9 atomes sont chargés dans le piège magnétique millimétrique de surface. Différentes expériences de caractérisation sont réalisées et expliquées à la lumières de simulations numériques. L'étude des fréquences de piégeage et de la profondeur a révélé les limites du premier prototype de piège millimétrique que nous avons réalisé au laboratoire. Cependant ces développements expérimentaux et théoriques servent à développer et implémenter dans le dispositif une nouvelle génération de puce à échelle micrométrique. / Atom interferometry has shown its interest for high precision measurements, such as inertial sensors, tests of fundamental physics or fundamental constant measurements. A way to improve sensitivity of such device is to reduce speed dispersion of the atomic cloud. The use of ultra-cold atoms allows increasing the interogation time of atoms and the spatial separation between the interferometer arms. The building of a new atom interferometer with separated arms is ongoing in the laboratory "Collisions Agrégats et Réactivité" at Toulouse. This new setup must meet two objectives. One aim of its conception is to study and develop a new kind of double species Bose-Einstein condensate (B.E.C.) source for atom interferometry with rubidium 87 and 85. This B.E.C. source relies on atom chip technology to cool down and manipulate atoms. This technology is compact and low power consuming, therefore suitable for transportable applications in space. A second aim is to use this interferometer to fix new boundary on the experimental value of atom neutrality thanks to the scalar Aharonov-Bohm effect. In this manuscript I start by exposing and justifying technical choices made for the design of the double isotope B.E.C. source. Then I present the first experimental results compared with numerical simulations and theoretical explanations. During the first laser cooling stage we produce a cloud including 4 × 10^10 rubidium atoms of both isotopes (87 and 85) at 10 µK. This operation can be repeated every second. Following the laser cooling 8×10^9 atoms are loaded into a millimeter sized magnetic trap. Various experiments were performed to characterize the trap. Studies of the trap frequency and depth revealed the limitations of this first prototype. However these theoretical and experimental developments led to design and future implementation of a new generation of micro-chip in our apparatus.

Les capteurs inertiels basés sur l’interférométrie atomique reposent sur l’utilisation d’atomes froids refroidis à des températures proches du micro-Kelvin et des temps d’interrogation de plusieurs centaines de millisecondes. Ces conditions conduisent à une extension du nuage d’atomes de l’ordre du cm, qui rend difficile leur interrogation efficace par des lasers à profil d’intensité gaussien. Cette thèse vise à développer plusieurs moyens de palier aux contraintes posés par le profil gaussien des lasers et leur intensité limitée. Deux axes principaux sont explorés.D'une part, l'inhomogénéité d'intensité des faisceaux d'interrogation a été adressée par l'étude, la réalisation et la caractérisation de solutions de mise en forme de faisceaux. Un modulateur spatial de phase a notamment été utilisé pour réaliser un faisceau plat en intensité et en phase de 3cm de diamètre. Une solution commerciale mise en vente durant la thèse a finalement été adaptée à une expérience d’interférométrie atomique, et son impact a été caractérisé.D’autre part, l’utilisation actuelle de lasers gaussiens de diamètres centimétriques pour adresser un maximum d’atomes apporte des contraintes sur les puissances utilisées. L’idée de profiter du gain en puissance de cavités optiques émerge dans le domaine et constitue le cœur de ce travail. Plusieurs concepts de résonateurs optiques ont été étudiés pour permettre l’amplification d’un mode de grande taille dans une géométrie compacte. Nous avons réalisé un résonateur dégénéré, intégrant une lentille intra-cavité, et avons étudié l’influence de ses désalignements et des défauts des optiques sur la résonance de grands faisceaux injectés.Ces deux dispositifs et leur couplage ouvrent la voie vers des générations avancées d’interféromètres atomiques, pour des expériences de précision en physique fondamentale ou pour la mise au point de capteurs inertiels à atomes froids compacts. / Inertials sensors based on atom interferometry use cold atom clouds cooled to micro-Kelvin temperatures and interrogation times of a few hundred of milliseconds.These conditions lead to an expansion of the atom clouds reaching centimetric sizes, which leads to difficulties when trying to adress them efficiently with gaussian laser beams.This work aims at developing different means to counteract the constraints brought by these gaussian beams and their limited intensity.Two main axes are explored.On the one hand, the intensity inhomogeneity of the interrogation beams has been adressed by the study, realisation and characterization of beamshaping solutions.One of these solutions has been adapted to an atom interferometry experiment, and its impact characterized.On the other hand, the current use of gaussian beams with centimetric sizes to interrogate as many atoms as possible brings constraints on the laser power.The idea of taking advantage of the optical gain of optical resonators rises in the field and constitutes the heart of this work.Different optical resonators concepts have been considered to allow the resonance of a large optical mode in a compact geometry.We built a degenerated optical resonator, with an intra-cavity lens, and studied the influence of misalignments and opticals defects on the resonance of large injected gaussian beams.These two devices and their combination open the way towards a generation of advanced atom interferometers, for precise experiments of fundamental physics or the development of compact cold atom inertial sensors.

Atom-surface interactions are becoming an integral part of the field of atom optics. Here the role of van der Waals atom-surface interactions in atom wave diffraction and interferometry are investigated. In particular, it is shown that van der Waals interactions influence the intensity and phase of atomic diffraction patterns obtained from material gratings. As a result the atomic diffraction patterns are utilized to make an accurate determination of the interaction strength and verify the spatial variation of the atom-surface potential. A theory for describing the modified atom wave diffraction patterns is developed through an analogy with optical waves. An atom interferometer is used to directly measure the de Broglie wave phase shift induced by atom-surface interactions. More specifically, the phases of the zeroth, first, and second diffraction orders are measured. A proposal for using electromagnetic fields to modify the van der Waals interaction is put forth. Several of the important experimental components for observing such an effect are also demonstrated.