Cold atom apparatuses have proven to be an invaluable tool in quantum many-body studies as they provide a platform for quantum simulations. These systems allow us to explore thousands of avenues related to neutron stars, novel technologies, quantum many-body physics and many more. Since joining the Sommer Laboratory group, I have made significant contribution to the design and construction of an ultracold 6Li apparatus. In this work I describe the design of a 'two-part' vacuum system for the injection and manipulation of lithium atoms. Additionally, I describe the lasersystems necessary to cool and capture hot lithium atoms to temperatures on the order of several hundred micro-kelvin. Finally I discuss the design and performance of our built apparatus at the time of this dissertation's submission. I will also give a brief overview of research that has led up to this point in the field of atomic physics followed by a description of our atomic apparatus and the future application of this apparatus.
Cold atom apparatuses have proven to be an invaluable tool in quantum many-body studies as they provide a platform for quantum simulations. These systems allow us to explore thousands of avenues related to neutron stars, novel technologies, quantum many-body physics and many more. Since joining the Sommer Laboratory group, I have made significant contribution to the design and construction of an ultracold 6Li apparatus. In this work I describe the design of a 'two-part' vacuum system for the injection and manipulation of lithium atoms. Additionally, I describe the lasersystems necessary to cool and capture hot lithium atoms to temperatures on the order of several hundred micro-kelvin. Finally I discuss the design and performance of our built apparatus at the time of this dissertation's submission. I will also give a brief overview of research that has led up to this point in the field of atomic physics followed by a description of our atomic apparatus and the future application of this apparatus.
An ultra-cold Fermi gas is a great way to simulate quantum many-body physics. The deeperunderstanding of strongly interacting fermionic systems gained from studying physics of such ultra-cold systems have found applications to high TC superconductors. The apparatus described here aims to study non-equilibrium dynamics and transport properties of unitary Fermi systems by optical cooling and trapping a cloud of 6Li atoms. My contribution to the design and construction of the Sommer group ultra-cold 6Li apparatus involves the design and construction of the Feshbach resonance electronics, AOM electronics for the laser system, setup of some of the AOM and ODT optics, and some coding. In this text I describe the design of our vacuum apparatus and laser system that traps and cools 6Li atoms to micro Kelvin temperatures, characterizes its performance, and describe how it can be utilized for spin transport experiments across normal-superfluid interface
Cavity quantum electrodynamics (cQED) is a central paradigm for the study of open quantum systems.The study of cQED aims to understand phenomena such as quantum decoherence and the emergence of semiclassical dynamics, striving to better connect empirical realism and axiomatic theory.Within this quantum regime, it is possible to prepare a mechanical oscillator in pure quantum states and observe how it evolves under interaction with the environment.Furthermore, quantum coupling of these mechanical systems to ultracold atomic systems offers a novel approach to controlling macroscopic systems at the quantum level.We are laying the experimental groundwork for hybrid atom-optomechanics where the optomechanical coupling is atom-mediated using an ultracold 6 Li atomic gas.The ultracold 6 Li gas is to be in close proximity with and strongly coupled to a high quality factor fused silica microtoroid resonator by confinement in a two-color evanescent wave optical dipole trap.The infrastructure, construction, and operation of an ultracold Li apparatus is presented and followed with a report of the characterization of our first observation of an ultracold lithium gas in the laboratory.Specifically, this thesis briefly covers theory and experimental implementation of laser cooling methods, development of the homemade laser and laser amplifier systems, and development and construction of the homemade electronic systems for the precise control and monitoring of atomic parameters.Finally, magneto-optical trap characterization methods and images of the cold atoms using time-dependent fluorescence imaging are shown and followed with a discussion of further work. ACKNOWLEDGMENTSMany people have contributed to the success of this thesis, and I owe thanks to all of them.First, I am grateful to Prof. Mukund Vengalattore for giving me the opportunity to be a part of his group and to work on building the lithium experiment.His incredible passion, never-ending myriad of ideas he contributed to this work, and the exceptional work environment he created have been crucial to the success of this thesis and to my development as a masters student.I owe much thanks to my colleague in the lithium-6 experiment, Yogesh Patil, for his invaluable insights and close to instant understanding of many of the technical difficulties and physical effects.Much of the success of this thesis results from his insights during our countless discussions.Thank you so much for the time we spent in the lab together!Many thanks to our undergraduate member, Airlia Shaffer-Moag, for a full set of crosstalk data on all 32 DIO circuits.Also, many thanks to all other group members from previous years who provided the original designs that the circuits in the lithium experiment are based upon.Finally, I am grateful to those who were not directly involved in the lithium-6 experiment but nevertheless contributed to making this thesis a successful and very pleasant one.First, I thank Lauren Aycock for her guidance, encouragement and invaluable suggestions in the lab and on this thesis.I thank Collin Reynolds for pointing out some very key circuit issues and for his constant feedback and encouragement.Finally, I thank Srivatsan Chakram for his help and insights and for his willingness to discuss my questions! b To my instructors, mentors, and colleagues.
During my PhD, I participated in the full setup from scratch of an experiment that aims at cooling down and manipulating two fermionic alkaline atomic species, 6Li and 40K. Our goal is to study ultracold Fermi mixtures with mass imbalance, and to realize a flexible quantum analog simulator. In fact, for certain quantum many-body problems, such as high critical temperature superconductivity and frustrated anti-ferromagnetism, there is neither complete analytical nor numerical solution. Therefore, cold atoms systems, due to their purity and their high degree of tunability, even on their interaction itself, offer an interesting complementary point of view in the study of those phenomena. As far as the experimental setup is concerned, we built an ultra-high vacuum system, a complete and stable laser source for each species, as well as two performing atomic sources, a 6Li Zeeman slower and a 40K bidimensionnal magneto-optical trap; most of the optical and electrical quantities, as well as the imaging diagnostics, being computer controlled. Once those preliminary steps have been performed and optimized, we could obtain an efficient double magneto-optical trap, containing typically 5x10^9 atoms of 6Li and 8x10^9 atoms of 40K. In this configuration, we produced the first 6Li40K* heteronuclear molecules by photoassociation, for which we identified 70 rovibrational lines. In a second part, I describe in detail the magnetic transport of the atomic mixture, between the magneto-optical trap chamber and a science cell, located in an ultra-high vacuum region with large optical access. The complete setup, from its design to its experimental implementation and optimization, as well as the development of the program and the useful numerical diagnostics, are the heart of my work. The transport efficiency could be tested and optimized, allowing for an efficient transfer of the mixture in the science cell. Thus, after this thesis, all the experimental tools are operational in order to allow for evaporative cooling of the mixture in an optically plugged magnetic trap. Therefore, the field is open for quantum simulation and understanding of many-body problems in ultracold Fermi mixtures.
Ultra-cold atoms have become an essential tool in studying unique phenomena in condensed matter systems such as superconductivity and quantum phase transitions. To accomplish these experiments we use an apparatus designed to trap and cool lithium atoms down to nano-Kelvin temperatures. Recently, significant upgrades to the laser system have been made to improve performance, increase stability, minimize maintenance and improve flexibility. We are working towards two exciting projects: proving the existence of an exotic superfluid state (FFLO) and probing the crossover between one and three-dimensions in a spin-1/2 Fermi gas with a spin-imbalance.
Ultracold gases provide a clean setup for investigating the many-body physics of stronglyinteracting fermions. Due to the universal nature of strongly interacting fermionic systems, an ultracold gas can serve as a quantum simulator for other strongly interacting systems of fermions such as neutron stars and high-Tc superconductors [1] [2]. A better understanding of such systems could potentially have great scientific and technological implications. In this thesis, I describe the construction of an apparatus that can be used for future experiments on ultracold atoms probing questions related to spin and heat transport in a strongly interacting gas of 6Li atoms. Multiple stages of cooling have been successfully completed on the way towards establishing a quantum degenerate ultracold gas of Li-6. To this end a magneto-optical trap (MOT) has been realized with a temperature on the order of ? 1mK, a compressed MOT (cMOT) has been realized with a temperature ? 600?K, and most recently a crossed optical-dipole trap (ODT) with a temperature ? 70?K. The foundations have also been laid for the final stage of atomic trapping in our apparatus, the multi-region trap, or "box trap"; in particular I will describe an optical setup that has been tested and is suitable for use in creating the hollow cylindrical walls or our box trap, which we like to call the "ring beam".
Ultracold mixture experiments hold the promise of providing new insights into many-body quantum systems as well as ultracold chemistry and few-body phenomena. The work presented in this thesis dealt with the construction of a new apparatus for the production and study of ultracold gases of fermionic lithium-6 and bosonic caesium-133. These isotopes offer a wide tunability in their interaction strength, both in inter-species and intra-species collisions, through magnetic Feshbach resonances. Additionally, the widely different resonance frequencies of lithium and caesium enables independent control of each of the species. With this apparatus, Bose-Einstein condensates (BEC) containing 10^4 lithium Feshbach molecules are routinely produced. The cooling system for caesium has been developed in parallel and important steps towards producing ultracold caesium gases have been made. An optical dipole trap has been loaded with 2x10^6 caesium atoms and evaporative cooling towards quantum degeneracy can now be pursued. Laser, vacuum, magnetic and control systems have been developed for the implementation of this experiment. Light produced with this laser system was used to laser cool atoms, create conservative dipole traps as well as to provide means of imaging atomic clouds. Additionally, a system to produce strong magnetic fields of up to 1400 G has been established in order to exploit the wide tunability in the atomic interactions. Software that was developed for the computerised control system facilitated the coordination of all the components involved in the experimental sequence. Measurements and calculations that showcase the functionality of relevant parts of the setup are presented in this thesis. In this experiment, lithium and caesium atoms are obtained from a novel type of Zeeman slower and are loaded into a magneto-optical trap (MOT). The system is capable of doing this independently for each of the atomic species as well as sequentially. After the MOT has been loaded with atoms, they are transferred into a conservative far-off-resonance optical dipole trap. By adjusting the interactions between atoms and lowering the depth of the dipole trap, efficient evaporative cooling of lithium was carried out from which a molecular BEC was obtained. Time-of-flight measurements were used to characterise the condensate and study its expansion dynamics.