Strongly Interacting Quantum Mixtures Of Ultracold Atoms
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Strongly Interacting Quantum Mixtures Of Ultracold Atoms
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Author : Cheng-Hsun Wu (Ph. D.)
language : en
Publisher:
Release Date : 2013
Strongly Interacting Quantum Mixtures Of Ultracold Atoms written by Cheng-Hsun Wu (Ph. D.) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
This thesis describes the construction of a new apparatus for ultracold quantum gases as well as the scientific results this machine has produced so far. This new apparatus is capable of simultaneously cooling and trapping lithium, sodium, and potassium. It therefore provides a platform to study a large variety of quantum mixtures. Three main experimental results are presented. Firstly, the direct cooling of "K to Bose-Einstein condensation is presented. Then the 41K atoms provide the coolant for 6Li and 40K, achieving a triply degenerate gas of 6Li -40K -41K. In particular, a broad interspecies Feshbach resonance between 40K -41K is observed, opening a new pathway to study a strongly interacting isotopic Bose-Fermi mixture of 40K -41K. Secondly, a new Bose-Fermi mixture of 23Na -40K is introduced. We show that 23Na is a very efficient coolant for 40K by sympathetically cooling 40K to quantum degeneracy with the help of a 23Na condensate. Moreover, over thirty interspecies Feshbach resonances are identified, paving the way to study strongly interacting Bose- Fermi problems, in particular the Bose polaron problem. Thirdly, we report on the first formation of ultracold fermionic Feshbach molecules of 23Na40K by radio-frequency association. The lifetime of the nearly degenerate molecular gas exceeds 100 ms in the vicinity of the Feshbach resonance. The NaK molecule features chemical stability in its ground state in contrast to the case of the KRb molecule. Therefore, our work opens up the prospect of creating chemically stable, fermionic ground state molecules of 23Na40K where strong, long-range dipolar interactions will set the dominant energy scale. Finally, the thesis concludes with an outlook on future topics in polaron physics and quantum dipolar gases, which can be studied using the new apparatus.
From Strongly Interacting Bose Fermi Mixtures To Ultracold Molecules
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Author : Zoe Ziyue Yan
language : en
Publisher:
Release Date : 2020
From Strongly Interacting Bose Fermi Mixtures To Ultracold Molecules written by Zoe Ziyue Yan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
This thesis describes experiments on ultracold quantum gases. First, I discuss quantum simulation involving mixtures of bosonic and fermionic atoms. Second, I present work on creating and controlling ultracold dipolar molecules of 23Na40K. The rich phase diagram of Bose-Fermi mixtures was studied with our system of bosonic 23Na and fermionic 40K atoms. When the fermions were immersed as a minority species within a Bose-Einstein condensate, the system realized the canonical Bose polaron quasiparticle, which is an important paradigm in condensed matter physics. We investigated the strongly-coupled Bose polaron as it approached the quantum critical regime of the Bose-Fermi mixture. Using radiofrequency spectroscopy, we probed the binding energy and decay rate as a function of temperature. In particular, the decay rate was found to scale linearly with temperature near the Planckian rate k[subscript B]T/h− in the unitarity-limited regime, a hallmark of quantum critical behavior. Bose-Fermi mixtures host a complex spectrum of collective excitations, which can shed light on their properties such as collisional relaxation rates, equilibrium equations of state, and kinetic coefficients. We probed the low-lying collective modes of a Bose-Fermi mixture across different interaction strengths and temperatures. The spin-polarized fermions were observed to transition from ballistic to hydrodynamic flow induced by interactions with the bosonic excitations. Our measurements establish Bose-Fermi mixtures as a fruitful arena to understand hydrodynamics of fermions, with important connections to electron hydrodynamics in strongly-correlated 2D materials. The second part of this thesis describes the creation and manipulation of ultracold molecules in their ground state. Molecules have more tunable degrees of freedom compared to atoms, paving the way for studies of quantum state-controlled chemistry, quantum information, and exotic phases of matter. We created loosely-bound Feshbach molecules from ultracold atoms, then transferred those molecules to their absolute electronic, vibrational, rotational, and hyperfine ground state by stimulated Raman adiabatic passage. The rotational level structure, sample lifetimes, and coherence properties were studied, culminating in a demonstration of second-scale nuclear spin coherence times in an ensemble of NaK. Controlling the intermolecular interactions - which can be tunable, anisotropic, and long range - is an outstanding challenge for our field. We induced strong dipolar interactions via the technique of microwave dressing, an alternative to using static electric fields to polarize the molecules. The origin of these dipolar collisions was the resonant alignment of the approaching molecules' dipoles along their intermolecular axis, resulting in strong attraction. Our observations were explained by a conceptually simple two-state picture based on the Condon approximation.
Physics On Ultracold Quantum Gases
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Author : Wei Yi
language : en
Publisher: World Scientific Publishing Company
Release Date : 2018
Physics On Ultracold Quantum Gases written by Wei Yi and has been published by World Scientific Publishing Company this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Cold gases categories.
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.
Ultracold Bosonic And Fermionic Gases
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Author : Kathy Levin
language : en
Publisher: Elsevier
Release Date : 2012-11-15
Ultracold Bosonic And Fermionic Gases written by Kathy Levin and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-11-15 with Science categories.
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
Quantum Matter At Ultralow Temperatures
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Author : M. Inguscio
language : en
Publisher: IOS Press
Release Date : 2016-09-27
Quantum Matter At Ultralow Temperatures written by M. Inguscio and has been published by IOS Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-09-27 with Science categories.
The Enrico Fermi summer school on Quantum Matter at Ultralow Temperatures held on 7-15 July 2014 at Varenna, Italy, featured important frontiers in the field of ultracold atoms. For the last 25 years, this field has undergone dramatic developments, which were chronicled by several Varenna summer schools, in 1991 on Laser Manipulation of Atoms, in 1998 on Bose-Einstein Condensation in Atomic Gases, and in 2006 on Ultra-cold Fermi Gases. The theme of the 2014 school demonstrates that the field has now branched out into many different directions, where the tools and precision of atomic physics are used to realise new quantum systems, or in other words, to quantum-engineer interesting Hamiltonians. The topics of the school identify major new directions: Quantum gases with long range interactions, either due to strong magnetic dipole forces, due to Rydberg excitations, or, for polar molecules, due to electric dipole interactions; quantum gases in lower dimensions; quantum gases with disorder; atoms in optical lattices, now with single-site optical resolution; systems with non-trivial topological properties, e.g. with spin-orbit coupling or in artificial gauge fields; quantum impurity problems (Bose and Fermi polarons); quantum magnetism. Fermi gases with strong interactions, spinor Bose-Einstein condensates and coupled multi-component Bose gases or Bose-Fermi mixtures continue to be active areas. The current status of several of these areas is systematically summarized in this volume.
Interactions In Ultracold Gases
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Author : Matthias Weidemüller
language : en
Publisher: John Wiley & Sons
Release Date : 2011-02-10
Interactions In Ultracold Gases written by Matthias Weidemüller and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-02-10 with Science categories.
Arising from a workshop, this book surveys the physics of ultracold atoms and molecules taking into consideration the latest research on ultracold phenomena, such as Bose Einstein condensation and quantum computing. Several reputed authors provide an introduction to the field, covering recent experimental results on atom and molecule cooling as well as the theoretical treatment.
Ultracold Molecules From Ultracold Atoms
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Author : Caleb A. Christensen
language : en
Publisher:
Release Date : 2011
Ultracold Molecules From Ultracold Atoms written by Caleb A. Christensen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
The thesis presents results from experiments in which ultracold Sodium-6 and Lithium-23 atomic gases were studied near a Feshbach resonance at high magnetic fields. The enhanced interactions between atoms in the presence of a molecular state enhance collisions, leading to inelastic decay and loss, many-body dynamics, novel quantum phases, and molecule formation. Experimental data is presented alongside relevant theory and numerical models. Results are presented for both homonuclear Na 2 and Li 2 molecules, as well as heteronuclear NaLi resonances, although we were unable to isolate and measure NaLi molecules. Furthermore, experiments and theories related to strongly-correlated quantum phases such as Stoner model ferromagnetism, Bose mediated Fermi interactions, and Bose-Fermi mixtures are presented as applicable to Na and Li gases. Conclusions are presented regarding the feasibility of producing deeply bound, dipolar NaLi molecules, as well as future prospects for strongly interacting atomic gases of Na and Li.
Topics In Ultracold Atomic Gases
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Author : Weiran Li
language : en
Publisher:
Release Date : 2013
Topics In Ultracold Atomic Gases written by Weiran Li and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Abstract: This thesis discusses two important topics in ultracold atomic gases: strong interactions in quantum gases, and quantum Hall physics in neutral atoms. First we give a brief introduction on basic scattering models in atomic physics, and an approach to adjust the interactions between atoms. We also include a list of experimental probes in cold atom physics. After these introductions, in Chapter 3, we report a few interesting problems in strongly interacting quantum gases. We introduce the BCS-BEC crossover model and relevant many-body techniques at the beginning, and discuss the details of several specific systems. We find the Fermi gases across narrow Feshbach resonances are strongly interacting at low temperature even when the magnetic field is several widths away from the resonance. We also discuss an approach to describe the metastable repulsive branch of Bose and Fermi gases across the resonance, and find a stable region of repulsive Bose gas close to unitarity. Some studies in two dimensional Fermi gases with spin imbalance are also included, and they are closely related to a number of recent experiments. In Chapter 4, we discuss quantum Hall physics in the context of neutral atomic gases. After illustrating how the Berry phase experienced by neutral atoms is equivalent to the magnetic field in electrons, we introduce the newly developed synthetic gauge field scheme in which a gauge potential is coupled to the neutral atoms. We give a detail introduction to this Raman coupling scheme developed by NIST group, and derive the theoretical model of the system. Then we make some predictions on the evolution of quantum Hall states when an extra anisotropy is applied from the external trap. Finally, we propose some experiments to verify our predictions.
Quantum Gas Experiments Exploring Many Body States
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Author : Paivi Torma
language : en
Publisher: World Scientific
Release Date : 2014-09-16
Quantum Gas Experiments Exploring Many Body States written by Paivi Torma and has been published by World Scientific this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-09-16 with Science categories.
Quantum phenomena of many-particle systems are fascinating in their complexity and are consequently not fully understood and largely untapped in terms of practical applications. Ultracold gases provide a unique platform to build up model systems of quantum many-body physics with highly controlled microscopic constituents. In this way, many-body quantum phenomena can be investigated with an unprecedented level of precision, and control and models that cannot be solved with present day computers may be studied using ultracold gases as a quantum simulator.This book addresses the need for a comprehensive description of the most important advanced experimental methods and techniques that have been developed along with the theoretical framework in a clear and applicable format. The focus is on methods that are especially crucial in probing and understanding the many-body nature of the quantum phenomena in ultracold gases and most topics are covered both from a theoretical and experimental viewpoint, with interrelated chapters written by experts from both sides of research.Graduate students and post-doctoral researches working on ultracold gases will benefit from this book, as well as researchers from other fields who wish to gain an overview of the recent fascinating developments in this very dynamically evolving field. Sufficient level of both detailed high level research and a pedagogical approach is maintained throughout the book so as to be of value to those entering the field as well as advanced researchers. Furthermore, both experimentalists and theorists will benefit from the book; close collaboration between the two are continuously driving the field to a very high level and will be strengthened to continue the important progress yet to be made in the field.
Computational Studies Of Strongly Interacting Ultracold Atoms
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Author :
language : en
Publisher:
Release Date : 2010
Computational Studies Of Strongly Interacting Ultracold Atoms written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
We develop and apply computational methods to investigate correlation effects in atomic and molecular systems, and in optical lattice systems. Problems from both classes are studied synergistically. We quantified effects of many-body correlations in trapped atomic Bose gases; developed auxiliary-field quantum Monte Carlo method for Bosons and fermions whose computational cost scales as N^3-N^4 with system size; benchmarked the method in molecular systems using Gaussian basis functions; demonstrated that its accuracy is comparable to the preeminent quantum chemistry coupled-cluster method CCSD(T) for systems near equilibrium geometry, and better than the latter when bonds are stretched or broken; developed methods to correct for finite-size errors to drastically improve the efficiency of many-body simulations by reaching larger and more realistic system sizes; formulated an approach to eliminate spin contamination in auxiliary-field calculations; examined spin-density waves states in simple models of metallic systems; showed the existence of incommensurate spin-density waves in two-dimensional optical lattices with positive scattering lengths.
