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This thesis describes the experimental realisation and characterisation of three non-trivial trapping geometries for ultracold atoms. The double-well, ring and to some degree shell trap are examples of a highly versatile class of traps called time-averaged adiabatic potentials (TAAPs). In this experiment the TAAPs arise from the combination of three independent magnetic fields; a static quadrupole field dressed by a uniform radio-frequency field is time- averaged by a bias field oscillating in the kHz regime. The result is a very smooth potential, within which ultracold atoms can be evaporatively cooled to quantum degeneracy, and subsequently manipulated into new geometries without destroying the quantum coherence. The vertically offset double-well potential provided the first example of ul- tracold atoms confined in a TAAP. The same potential is used to demonstrate efficient evaporative cooling across the Bose-Einstein condensate (BEC) phase transition using only the Landau-Zener loss mechanism. Switching off the time- averaging fields loads atoms from the double-well TAAP into the rf-dressed shell trap. A characterisation of this potential measured low heating rates and life- times of up to 58 s. With efforts ongoing to increase the trap anisotropy, this potential shows promise for research into the static and rapidly rotating 2D systems. In the presence of a single time-averaging field, the shell geometry is transformed into a ring-shaped trap with an adjustable radius. The ring trap can be controllably tilted and progress towards multiply connected condensates is being made. A rotation scheme to spin up atoms in the ring trap has been demonstrated, presenting the opportunity to investigate the dynamics of super- flow in degenerate quantum gases.
This volume provides a broad overview of the principal theoretical techniques applied to non-equilibrium and finite temperature quantum gases. Covering Bose-Einstein condensates, degenerate Fermi gases, and the more recently realised exciton-polariton condensates, it fills a gap by linking between different methods with origins in condensed matter physics, quantum field theory, quantum optics, atomic physics, and statistical mechanics.
The book addresses several aspects of thermodynamics and correlations in the strongly-interacting regime of one-dimensional bosons, a topic at the forefront of current theoretical and experimental studies. Strongly correlated systems of one-dimensional bosons have a long history of theoretical study. Their experimental realisation in ultracold atom experiments is the subject of current research, which took off in the early 2000s. Yet these experiments raise new theoretical questions, just begging to be answered. Correlation functions are readily available for experimental measurements. In this book, they are tackled by means of sophisticated theoretical methods developed in condensed matter physics and mathematical physics, such as bosonization, the Bethe Ansatz and conformal field theory. Readers are introduced to these techniques, which are subsequently used to investigate many-body static and dynamical correlation functions.
This book derives from the content of graduate courses on cold atomic gases, taught at the Renmin University of China and at the University of Science and Technology of China. It provides a brief review on the history and current research frontiers in the field of ultracold atomic gases, as well as basic theoretical description of few- and many-body physics in the system. Starting from the basics such as atomic structure, atom-light interaction, laser cooling and trapping, the book then moves on to focus on the treatment of ultracold Fermi gases, before turning to topics in quantum simulation using cold atoms in optical lattices.The book would be ideal not only for professionals and researchers, but also for familiarizing junior graduate students with the subject and aiding them in their preparation for future study and research in the field.
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
This book provides authoritative tutorials on the most recent achievements in the field of quantum gases at the interface between atomic physics and quantum optics, condensed matter physics, nuclear and high-energy physics, non-linear physics, and quantum information.
Advances in Atomic, Molecular, and Optical Physics, Volume 66 provides a comprehensive compilation of recent developments in a field that is in a state of rapid growth. New to this volume are chapters devoted to 2D Coherent Spectroscopy of Electronic Transitions, Nonlinear and Quantum Optical Properties and Applications of Intense Twin-Beams, Non-classical Light Generation from III-V and Group-IV Solid-State Cavity Quantum Systems, Trapping Atoms with Radio Frequency Adiabatic Potentials, Quantum Control of Optomechanical Systems, and Efficient Description of Bose–Einstein Condensates in Time-Dependent Rotating Traps. With timely articles written by distinguished experts that contain relevant review materials and detailed descriptions of important developments in the field, this series is a must have for those interested in the variety of topics covered. Presents the work of international experts in the field Contains comprehensive articles that compile recent developments in a field that is experiencing rapid growth, with new experimental and theoretical techniques emerging Ideal for users interested in optics, excitons, plasmas, and thermodynamics Topics covered include atmospheric science, astrophysics, surface physics, and laser physics, amongst others
In this thesis I explore the possibility of accelerating adiabatic processes for quantum systems. Experiments are performed with a trapped ultracold gas of Rubidium-87 atoms in two distinct regimes: with a one-dimensional thermal gas that can be considered non-interacting, and with a three-dimensional Bose-Einstein condensate for which interactions are dominant. In the first chapter I recall some aspects of the theoretical description and important properties of such gases. The second chapter details the construction of a Bose-Einstein condensation apparatus, mainly composed of two magneto-optical traps and a magnetic trap. In the third chapter this set-up is used to demonstrate that adiabatic processes, in our case, the slow decompression and displacement of the gas, can be dramatically accelerated by using a proper design of the time-dependent parameters of the system. The theoretical treatment is detailed and is not restricted to trapped gases. It may be applied to other physical systems described by either a linear or nonlinear Schrödinger equation containing a time-dependent harmonic potential. The final chapter is theoretical and not directly related to the others. In it I investigate the effect of disorder correlations on one-dimensional Anderson localization. I show that a degenerate mixture of Rubidium-87 and Potassium-41 atoms is well suited to study the localization-delocalization transition predicted by existing models of correlated disorder.
The experimental achievement of Bose-Einstein condensation (1995) and of Fermi degeneracy (1999) in ultra-cold, dilute gases has opened a new field in atomic physics and condensed matter physics. This thesis presents an overview of theoretical and experimental facts on ultra-cold atomic gases. A Green's function scheme is examined, and the book also applies a novel spin-density-functional approach to the study of Fermi gases inside one-dimensional optical lattices.