Since atom interferometers were first realized about 20 years ago, atom interferometry has had many applications in basic and applied science, and has been used to measure gravity acceleration, rotations and fundamental physical quantities with unprecedented precision. Future applications range from tests of general relativity to the development of next-generation inertial navigation systems. This book presents the lectures and notes from the Enrico Fermi school "Atom Interferometry", held in Varenna, Italy, in July 2013. The aim of the school was to cover basic experimental and theoretical aspects and to provide an updated review of current activities in the field as well as main achievements, open issues and future prospects. Topics covered include theoretical background and experimental schemes for atom interferometry; ultracold atoms and atom optics; comparison of atom, light, electron and neutron interferometers and their applications; high precision measurements with atom interferometry and their application to tests of fundamental physics, gravitation, inertial measurements and geophysics; measurement of fundamental constants; interferometry with quantum degenerate gases; matter wave interferometry beyond classical limits; large area interferometers; atom interferometry on chips; and interferometry with molecules. The book will be a valuable source of reference for students, newcomers and experts in the field of atom interferometry.

This thesis presents experimental results from the Stanford 10 m atom drop tower. We use atomic physics and laser spectroscopic techniques to test both general relativity and quantum mechanics. By dropping different types of atoms and observing their free-fall accelerations, it will be possible to test the equivalence principle and other general relativistic effects in the lab. By observing coherence after splitting an atom by up to 8.2 cm, we have probed the quantum-to-classical transition with increasingly macroscopic superposition states.

The rapidly developing topic of ultracold atoms has many actual and potential applications for condensed-matter science, and the contributions to this book emphasize these connections. Ultracold Bose and Fermi quantum gases are introduced at a level appropriate for first-year graduate students and non-specialists such as more mature general physicists. The reader will find answers to questions like: how are experiments conducted and how are the results interpreted? What are the advantages and limitations of ultracold atoms in studying many-body physics? How do experiments on ultracold atoms facilitate novel scientific opportunities relevant to the condensed-matted community? This volume seeks to be comprehensible rather than comprehensive; it aims at the level of a colloquium, accessible to outside readers, containing only minimal equations and limited references. In large part, it relies on many beautiful experiments from the past fifteen years and their very fruitful interplay with basic theoretical ideas. In this particular context, phenomena most relevant to condensed-matter science have been emphasized. - Introduces ultracold Bose and Fermi quantum gases at a level appropriate for non-specialists - Discusses landmark experiments and their fruitful interplay with basic theoretical ideas - Comprehensible rather than comprehensive, containing only minimal equations

Light-pulse atom interferometry--in which quantum mechanical atomic wave packets are split along two paths and later recombined and made to interfere by sequences of optical pulses--is a remarkably sensitive technique for measuring inertial forces, allowing it to be a valuable tool for applications ranging from fundamental tests of gravity to geodesy and inertial navigation. The inertial sensitivity of an atom interferometer is proportional to its enclosed spacetime area--that is, the product of the spatial separation between the two interferometer paths and the interferometer duration. Therefore, new techniques that allow this spacetime area to be increased are essential in order for atom interferometry to reach its full potential. In this thesis, I describe the development of such techniques. We approach the problem of increasing the interferometer spacetime area on two fronts. First, we implement new methods to increase the momentum transferred by the beam splitters of the interferometer. The velocity difference and therefore the spatial separation of the interferometer paths are proportional to this momentum transfer. Conventional atom optics techniques involve beam splitters that transfer two photon momentum recoils (2 hbar k) to the atoms. I will discuss our realization of large momentum transfer (LMT) beam splitters that transfer up to 100 hbar k. Second, we have built a 10 m tall atomic fountain that allows the total interferometer duration to be increased to 2 s. Ultimately, we combined LMT atom optics with long-duration atom interferometry in the 10 m atomic fountain, leading to very large spacetime area atom interferometers. In these very large area atom interferometers, the separation between the two atomic wave packets that respectively travel along the two interferometer paths reaches distances of up to 54 cm. Therefore, in addition to offering greatly increased inertial sensitivity, these interferometers probe the quantum mechanical wavelike nature of matter in a new macroscopic regime. I will discuss the techniques we devised to overcome the many technical challenges associated with such interferometers, which in other apparatus have prevented interference from being maintained for path separations larger than 1 cm. I will also describe initial results from the use of our very large area interferometers to test the equivalence principle with Rb-85 and Rb-87 and our plans for further progress in this direction. Very large area atom interferometry requires high laser power and extremely cold atom sources. We have developed a novel high power, frequency doubled laser source at 780 nm that is suitable for atom optics. Also, we have implemented a sequence of matter wave lenses to prepare and measure atomic ensembles with record-low effective temperatures of 50 pK. In addition to applications in atom interferometry, we expect that such an atom source will be broadly useful for a wide range of experiments.

The realisation of cold and slow atomic beams has opened the way to a series of precision measurements of high scientific interest, as atom interferometry, Bose-Einstein Condensation and atomic fountain clocks. The latter are used since several years as reference clocks, given the high performance that they can reach both in accuracy and stability. The common philosophy in the construction of atomic fountains has been the pulsed technique, where an atoms sample is launched vertically and then falls down under the effect of the gravity. The Observatoire de Neuchâtel had a different approach and has built a fountain clock (FOCS1) operating in a continuous mode. This technique offers two main advantages: the diminution of the undesirable effects due to the atomic density (e.g. collisions between the atoms and cavity pulling) and to the noise of the local oscillator (intermodulation effect). To take full advantage of the continuous fountain approach however, we need to increase the atomic flux. The techniques chosen to reach this goal are an efficient transverse collimation together with more atoms to begin with. Here we report on a study of different transverse collimation techniques performed in a two-dimensional phase stable optical lattice (namely gray molasses and magnetically induced laser cooling) as well as the development and characterisation of a 2D-magneto-optical trap used to load the fountain. Best performances are reached in a 2D+-MOT configuration of such a pre-source, for which we detect an atomic flux 20 times greater than the one measured when the fountain is loaded by a Cs vapour. This gain could improve the atomic clock stability by a factor 6. An even better stability is expected after introducing a pre-cooling stage before performing the transverse collimation. This new configuration is currently under investigation and will be implemented in a second continuous fountain (FOCS2).

A number of atom interferometry methods have been introduced and the state of the art in precision atom interferometry have been advanced. An interferometer using laser cooled atoms in an atomic fountain and off-resonant optical Raman pulses between ground states of the atom has been applied to the measurement of the ratio of planck's constant to mass, which is a step in the determination of the fine structure constant. The result has surpassed the next best measurement (the Quantum Hall Effect measurement) by a factor of ten in precision. Also, using an atomic interferometer as an accelerometer, the value of g has been measured and compared to that of the previous best absolute gravimeter (based on a falling corner-cube optical interferometer) with comparable results. Using 'optical tweezers' based on laser trapping techniques, experimental verification of the reputation theory of polymer dynamics, developed by de Genes twenty-five years ago, have been achieved. Other techniques and measurements have been unable to provide the needed verification.

This edition contains carefully selected contributions by leading scientists in high-resolution laser spectroscopy, quantum optics and laser physics. Emphasis is given to ultrafast laser phenomena, implementations of frequency combs, precision spectroscopy and high resolution metrology. Furthermore, applications of the fundamentals of quantum mechanics are widely covered. This book is dedicated to Nobel prize winner Theodor W. Hänsch on the occasion of his 75th birthday. The contributions are reprinted from a topical collection published in Applied Physics B, 2016. Selected contributions are available open access under a CC BY 4.0 license via link.springer.com. Please see the copyright page for further details.

This book gathers the lecture notes of courses given at Session CVII of the summer school in physics, entitled "Current Trends in Atomic Physics" and held in July, 2016 in Les Houches, France. Atomic physics provides a paradigm for exploring few-body quantum systems with unparalleled control. In recent years, this ability has been applied in diverse areas including condensed matter physics, high energy physics, chemistry and ultra-fast phenomena as well as foundational aspects of quantum physics. This book addresses these topics by presenting developments and current trends via a series of tutorials and lectures presented by international leading investigators.