Dissertations / Theses on the topic 'Ultracold atoms'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Ultracold atoms.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Piotrowicz, Michal J. "Ultracold Rydberg atoms." Thesis, Open University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.530495.
Full textTreutlein, Philipp. "Coherent manipulation of ultracold atoms on atom chips." Diss., kostenfrei, 2008. http://edoc.ub.uni-muenchen.de/9153/.
Full textEdmunds, P. D. "Trapping ultracold argon atoms." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1462806/.
Full textSala, Simon Johannes. "Ultracold atoms in traps." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17471.
Full textThis thesis aims for a theoretical description of ultracold trapped atoms. The main focus are resonance phenomena due to the coupling of center-of-mass and relative motion, the development of a theoretical approach to treat ultracold few-body systems in versatile trap potentials, and the quantum simulation of attosecond physics with ultracold atoms.
Polo, Gomez Juan. "Tunneling dynamics of ultracold atoms." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/400375.
Full textThe theory of Quantum Mechanics led to the discovery of many phenomena that were previously hidden by its probabilistic nature. In particular, Quantum Mechanics brought to light the so-called wave-particle duality behavior of extremely small objects. This behavior is typically obtained in isolated systems, therefore experiments where particles do not interact with the environment are basic to study quantum systems and quantum phenomena. Ultracold atoms are systems where atoms are cooled down to temperatures of the order of nanokelvin and, in general, kept in ultrahigh vacuum chambers, such that they can be studied in a highly controlled environment. Within this field, Bose—Einstein condensates (BECs) are a particular appealing state of matter where all the particles of an ultracold bose gas, macroscopically occupy a single quantum state. This behavior makes BECs ideal for studying quantum phenomena at a macroscopic scale. In this thesis, we investigate systems where, a quantum phenomenon that has no analogue in classical mechanics, the quantum tunneling is, or has the potential to be, the mechanism that triggers the dynamics. A tunneling event occurs whenever a massive particle is able to access a classically forbidden region of space without having the necessary kinetic energy to do it. Note that this phenomenon can arise in different scenarios, for instance a particle can tunnel when colliding with a potential barrier or it can simply oscillate between two separated wells separated by a potential barrier. In this context, first, we consider the implementation of a matter-wave bright soliton interferometer whose splitting mechanism is based on tunneling through a finite width barrier. We use bright matter-wave solitons in one dimensional BECs as they present properties, such as their dispersionless behavior, that are ideal for interferometric purposes. As mentioned previously, we are also interested on systems where tunneling occurs between neighboring potentials. For those cases, in order to estimate the tunneling amplitudes that couple the eigenstates of the local traps, the analytical density profiles of the eigenstates are required, especially around the low density regions. In particular, we study the density profiles of harmonically trapped two-component BECs within the miscible phase. The analytical formulation of the density profiles of each component around the low density regions is given by means of universal equations. We then turn our attention to the dynamics of single atoms in tunnel-coupled potentials. First, we study spatial adiabatic passage processes as a robust and efficient technique to transport and load single atoms between cylindrically symmetric concentric potentials. The two processes investigated are based on the matter-wave analogues of the rapid adiabatic passage and of the stimulated Raman adiabatic passage. With these techniques, we are able to transport the atom between two and three rings and to load an ultracold atom from a harmonic potential to a concentric ring. Next, we continue investigating ring potentials, but instead of using concentric rings, we use sided-coupled rings and we demonstrate that in this system, complex tunneling amplitudes appear naturally in the dynamics of single atom angular momentum states. We also propose to use this feature to engineer spatial dark states through quantum interference. Finally, we demonstrate how spatial dark states can be used to create edge-like states in an optical ribbon either for the manifold of ground states of the traps forming the ribbon or for states carrying orbital angular momentum. We show that these states are robust and that can be extended to other geometries. In addition, we suggest to use the winding number associated to the angular momentum as a synthetic dimension opening the possibility to quantum simulate three dimensional systems with two dimensional lattices.
Harte, Tiffany. "Ultracold atoms in dressed potentials." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:1a4ea098-ec17-414a-8873-95d83ca8ea97.
Full textMirandés, Rivera Estefania de. "Bloch oscillations of ultracold atoms." Paris 6, 2006. http://www.theses.fr/2006PA066622.
Full textHabibian, Hessam. "Cavity Quantum Electrodynamics with Ultracold Atoms." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/120180.
Full textIn this thesis we investigate the interactions between ultracold atoms confined by a periodic potential and a mode of a high-finesse optical cavity whose wavelength is incommensurate with the potential periodicity. The atoms are driven by a probe laser and can scatter photons into the cavity field. When the von-Laue condition is not satisfied, there is no coherent emission into the cavity mode. We consider this situation and identify conditions for which different nonlinear optical processes can occur. We characterize the properties of the light when the system can either operate as a degenerate parametric amplifier or as a source of antibunched light. Moreover, we show that the stationary entanglement between the light and spinwavemodes of the array can be generated. In the second part we consider the regime in which the zero-point motions of the atoms become relevant in the dynamics of atom-photon interactions. Numerical calculations show that for large parameter regions, cavity backaction forces the atoms into clusters with a local checkerboard density distribution. The clusters are phase-locked to one another so as to maximize the number of intracavity photons.
Grass, Tobias. "Ultracold atoms in artificial gauge fields." Doctoral thesis, Universitat Politècnica de Catalunya, 2013. http://hdl.handle.net/10803/117523.
Full textPelegrí, Andrés Gerard. "Ultracold atoms carrying orbital angular momentum." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/670113.
Full textDebido a la gran flexibilidad que ofrecen en su manipulación y control, los sistemas de átomos ultrafríos son ideales para simular un amplio abanico de modelos de materia condensada y constituyen una plataforma muy prometedora para la implementación de nuevas tecnologías cuánticas. En este contexto, la atomtrónica se ha establecido recientemente como un nuevo campo de investigación cuyo objetivo es crear circuitos de ondas de materia con átomos ultrafríos manipulados mediante micro trampas ópticas versátiles, con el doble propósito de explorar nuevos fenómenos físicos y de construir dispositivos cuánticos como sensores u ordenadores. Los circuitos atomtrónicos más sencillos están formados por potenciales en forma de anillo, los cuales proporcionan caminos cerrados para los átomos que admiten de manera natural estados con Momento Angular Orbital (MAO). Inspirados por estos avances, en esta tesis investigamos diversos sistemas que comparten la característica de estar formados por átomos ultrafríos con carga de MAO en potenciales con simetría cilíndrica. Nuestro interés se centra en tres aspectos de los estados con MAO: su potencial para fabricar sensores, sus aplicaciones en la simulación de modelos de magnetismo cuántico, y las posibilidades que ofrecen para obtener estados topológicos. Empezamos considerando un condensado de Bose-Einstein (CBE) atrapado en un único potencial en forma de anillo y preparado en una superposición de estados con MAO que rotan en direcciones opuestas. El perfil de esta superposición muestra una línea de mínima densidad que gira debido a la interacción no lineal entre los átomos. Después de deducir una expresión que relaciona la frecuencia de esta rotación con la fuerza de las interacciones, proponemos protocolos que permiten utilizar el sistema como un sensor de interacciones a dos cuerpos, campos magnéticos y rotaciones. A continuación, estudiamos diferentes configuraciones de potenciales acoplados lateralmente en las que los átomos ultrafríos experimentan una dinámica de efecto túnel gobernada por amplitudes complejas con fases que se pueden variar modificando la geometría del sistema. En primer lugar, exploramos una red en forma de cadena de diamante llena con átomos no interactuantes en estados con MAO. En este sistema, las fases de las amplitudes de efecto túnel complejas dan lugar a una estructura de bandas topológica con sus correspondientes estados de borde. Además, ajustando de forma adecuada las amplitudes de efecto túnel, se puede obtener un espectro de energías compuesto únicamente de bandas planas. En este caso, el sistema muestra confinamiento de Aharonov-Bohm. En segundo lugar, analizamos una familia de sistemas consistente en distribuciones de potenciales de anillo con una geometría flexible llenas con bosones fuertemente correlacionados en estados de MAO. Nos centramos en el régimen de aislante de Mott con un átomo por trampa, en el que se puede establecer una correspondencia entre estados con MAO y de espín-1/2. Mostramos que, ordenando las trampas de manera adecuada, estos sistemas pueden simular diferentes modelos de espín de interés relacionados con un modelo de Heisenberg general. Seguidamente nos volvemos a fijar en la cadena de diamante para investigar la física de dos bosones con interacción atractiva en el límite en el que todas las bandas son planas. En esta situación, la energía cinética no juega ningún papel y las propiedades del sistema vienen determinadas únicamente por las interacciones. Mostramos que el sector de baja energía del espectro de estados de dos bosones se puede describir en términos de modelos efectivos de una sola partícula que son topológicamente no triviales. Finalmente, estudiamos una red cuadrada en dos dimensiones con diferentes separaciones fuera y dentro de la celda unidad. Demostramos que este sistema constituye un ejemplo de aislante topológico de segundo orden, presentando un momento cuadrupolar finito y estados de esquina protegidos.
Due to their high degree of tunability and controllability, ultracold atom systems constitute an ideal playground for simulating a wide variety of condensed matter models and are one of the most promising platforms for the implementation of novel quantum technologies. In this context, the emerging field of atomtronics aims at realizing matter-wave circuits with ultracold atoms in versatile optical micro-traps. These efforts have a two-fold purpose: exploring new fundamental physics and constructing quantum devices such as sensors or computers. The simplest atomtronic circuits are formed by ring-shaped potentials, which provide closed loops for the atoms that naturally support Orbital Angular Momentum (OAM) states. Motivated by these advances, in this thesis we investigate different systems that have the common characteristic of being formed by ultracold atoms carrying OAM in cylindrically symmetric potentials. Our interest is focused on three aspects of OAM states: their potential use for sensing purposes, their applications as quantum simulators of models of quantum magnetism, and the possibilities that they offer for realizing topological phases of matter. We start by considering a Bose Einstein Condensate (BEC) trapped in a single ring potential and prepared in a superposition of counter-rotating OAM states. The density profile of this state has a minimal line that rotates due to the non-linear interaction between the atoms. After deriving an expression that relates the frequency of this rotation with the strength of the interactions, we propose protocols to use the system as a device for sensing two-body interactions, magnetic fields and rotations. Next, we explore several configurations of side-coupled potentials where ultracold atoms in OAM states experience tunnelling dynamics that are governed by complex amplitudes with phases that can be tuned by modifying the geometry of the system. First, we study a lattice with a diamond chain shape filled with non-interacting ultracold atoms carrying OAM. In this system, the phases in the tunnelling rates give rise to a topological band structure with its corresponding protected edge states. Furthermore, a proper tuning of the tunneling parameters may lead to an energy spectrum composed entirely of flat bands. In this scenario, the system exhibits Aharonov-Bohm caging. We then analyse a family of systems consisting of arrays of ring potentials with a flexible geometry filled with strongly correlated bosons in OAM states. We focus on the Mott insulator regime at unit filling, for which one can establish a correspondence between OAM and spin-1/2 states. We demonstrate that by properly arranging the traps, these systems can realize different spin models of interest related to a general Heisenberg model. Then, we turn our attention back to the diamond chain to examine the physics of two attractively interacting bosons in the limit when all bands are flat. In this situation, the kinetic energy is frozen and the properties of the system are solely determined by the interactions. We show that the low-energy sector of the two-boson spectrum can be described in terms of effective single-particle models that are topologically non-trivial. Finally, we investigate a two-dimensional square lattice with different intra- and inter-cell spacings in the non-interacting limit. We show that this system constitutes an example of a second-order topological insulator, displaying a finite quadrupole moment and protected corner states.
Rey, Ana Maria. "Ultracold bosonic atoms in optical lattices." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1802.
Full textThesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Camerer, Stephan. "Interfacing ultracold atoms and mechanical oscillators." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-130346.
Full textSaers, Robert. "Ultracold rubidium atoms in periodic potentials." Doctoral thesis, Umeå universitet, Fysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1821.
Full textThomas, Nicholas, and n/a. "Double-TOP trap for ultracold atoms." University of Otago. Department of Physics, 2005. http://adt.otago.ac.nz./public/adt-NZDU20070321.160859.
Full textTorralbo, Campo Lara. "A compact system for ultracold atoms." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3192.
Full textEngland, Duncan. "Towards ultrafast photoassociation of ultracold atoms." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:1e2a7450-e568-4f11-9c56-bb62250cd3df.
Full textViebahn, Konrad Gilbert Heinrich. "Quasicrystalline optical lattices for ultracold atoms." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/287942.
Full textBowman, David. "Ultracold atoms in flexible holographic traps." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/16293.
Full textSmith, Dane Hudson. "Resonant Floquet scattering of ultracold atoms." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1478192866433031.
Full textAigner, Simon. "Magnetic field microscopy using ultracold atoms." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:16-opus-79425.
Full textvon, Stecher Javier. "Trapped ultracold atoms with tunable interactions." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3315828.
Full textFancher, Charles. "Ac Zeeman Force with Ultracold Atoms." W&M ScholarWorks, 2016. https://scholarworks.wm.edu/etd/1499449866.
Full textSighinolfi, Matteo. "Open quantum systems and ultracold atoms." Doctoral thesis, Università degli studi di Trento, 2022. https://hdl.handle.net/11572/338501.
Full textChristensen, Caleb A. "Ultracold molecules from ultracold atoms : interactions in sodium and lithium gas." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68868.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 218-226).
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.
by Caleb A. Christensen.
Ph.D.
Zamora, Alejandro. "Quantum gauge theory simulation with ultracold atoms." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/285115.
Full textL'estudi dels àtoms ultrafreds constitueix una de les àrees més actives de la física atòmica, molecular, òptica i de l'òptica quàntica. Els èxits teòrics i experimentals de les tres últimes dècades sobre el control i la manipulació de la matèria quàntica en escala macroscòpica condueix a l'anomenada tercera revolució quàntica. Concretament, els recents avenços en els estudis dels àtoms ultrafred en xarxes òptiques proporcionen un sistema que es pot reajustar i reorganitzat per imitar el comportament d'altres sistemes de molts cossos: els gasos d'àtoms ultrafreds en xarxes òptiques actuen com a genuïns simuladors quàntics. La comprensió de les teories de gauge és clau per a la descripció de les interaccions fonamentals del nostre món físic. Particularment, les teories de gauge descriuen una de les més importants classes de sistemes que poden ser tractats amb simuladors quàntics. L'objectiu principal de la tesi és estudiar la implementació de simuladors quàntics de teories de gauge amb gasos d'àtoms ultrafreds en xarxes òptiques. En primer lloc, analitzem un sistema format per un gas ultrafred no interaccionant en una xarxa 2D sota l'acció d'un camp de gauge exòtic i extern provinent del grup de gauge de Heisenberg-Weyl. Descrivim un nou mètode per simular el grau de llibertat gauge, que consisteix a associar la coordenada gauge a una coordenada real i perpendicular a l'espai 2D de les posicions. Així, el sistema resultar ser un aïllant 3D amb topologia no trivial, concretament un aïllant Hall quàntic. Seguidament, estudiem un simulador quàntic analògic de camps de gauge dinàmics amb àtoms alcalinoterris en una xarxa hexagonal. Al régim fortament repulsiu amb un àtom en cada lloc, l'estat fonamental és un líquid espinorial quiral amb la simetria d'inversió temporal trencada. Les fluctuacions d'espín al voltant d'aquesta configuració vénen descrites per una teoria gauge U(1) emergent amb un terme topològic de Chern-Simons. També tractem l'estabilitat dels tres estats amb mínima energia, tot observant una temperatura crítica comuna. Considerem indicis experimentals mesurables dels estats de camp mitjà, que poden ser claus per revelar l'estructura gauge. A continuació, introduïm un enfoc constructiu per a teories gauge en el reticle, la qual porta a una família de teories de gauge, els magnets de gauge. Aquesta família es correspon amb els models d'enllaços quàntics de la teoria gauge U(1). Primer, (re)descobrim el diagrama de fases del magnet de gauge en 2+1 D. Després, proposem una implementació realista d'un simulador quàntic digital del magnet de gauge U(1) amb àtoms de Rydberg, considerant que el nombre de recursos necessaris per a la simulació dels models d'enllaços es redueix dràsticament pel fet que l'espai d' Hilbert local disminueix de dimensió infinita a 2 (bit quàntic). Finalment, motivats pels avenços en la simulació de sistemes quàntics oberts, considerem alguns aspectes de la dinàmica de sistemes quàntics correlacionats de molts cossos. Específicament, estudiem l'evolució temporal en un protocol de canvi sobtat que conserva l'espectre d'entrellaçament d'una bipartició. Considerem la ruptura d'una cadena d'Ising en dues cadenes independents i ho comparem amb la unió de dues cadenes, la qual no conserva l'espectre d'entrellaçament
El estudio de los átomos ultrafríos constituye una de las áreas mas activas de la física atómica, molecular, óptica y de la óptica cuántica. Los logros teóricos y experimentales de las tres últimas décadas sobre el control y la manipulación de la materia cuántica a escala macroscópica conducen a la denominada tercera revolución cuántica. Concretamente, los avances recientes en los estudios de átomos ultrafríos en redes ópticas proporcionan un sistema que puede ser reajustado y reorganizado para imitar el comportamiento de otros sistemas de muchos cuerpos: los gases de átomos ultrafríos en redes ópticas actúan como genuinos simuladores cuánticos. La comprensión de las teorías de gauge es clave para la descripción de la interacciones fundamentales de nuestro mundo físico. En particular, las teorías de gauge describen una de las mas importante clase de sistemas que pueden ser abordados con simuladores cuánticos. El objetivo principal de la tesis es estudiar la implementación de simuladores cuánticos de teorías de gauge con gases de átomos ultrafríos en redes ópticas. En primer lugar, analizamos un sistema formado por un gas ultrafrío no interactuante en una red 2D, bajo la acción de un campo de gauge exótico y externo descrito por el grupo de gauge de Heisenberg-Weyl. Describimos un método novedoso para simular el grado de libertad gauge , que consiste en asociar la coordenada gauge a una coordenada real y perpendicular al espacio 2D de las posiciones. Así, el sistema resulta ser un aislante 3D con una topología no trivial, específicamente un aislante Hall cuántico. Seguidamente, estudiamos un simulador cuántico analógico de campos de gauge dinámicos, considerando átomos alcalinotérreos en una red hexagonal. En el régimen fuertemente repulsivo con una átomo en cada sitio, el estado fundamental es un liquido espinorial quiral con la simetría de inversión temporal rota. Las fluctuaciones de espín alrededor de dicha configuración vienen dadas en términos de una teoría de gauge U(1) emergente con un término topológico de Chern-Simons. También tratamos la estabilidad de los tres estados con mínima energía, observando una temperatura crítica común. Consideramos indicios experimentales medibles de los estados de campo medio, que pueden claves para revelar la estructura de gauge. A continuación, introducimos la noción del enfoque constructivo para teorías de gauge en el retículo, lo que conduce a una familia de teorías de gauge, los magnetos de gauge. Esta familia se corresponde con los modelos de enlaces cuánticos para la teoría de gauge U(1), los cuales consideran una representación dimensional truncada del grupo de gauge. Primeramente, (re)descubrimos el diagrama de fases del magneto de gauge en 2+1D. Seguidamente, proponemos un implementación realista de un simulador cuántico digital del magneto de gauge U(1) usando átomos de Rydberg, considerando que el número de recursos necesarios para la simulación de los modelos de enlace está drásticamente reducido debido a que el espacio de Hilbert local disminuye de infinitas dimensiones a 2 (bit cuántico). Finalmente, motivados por los avances en la simulación de sistemas cuánticos abiertos, consideramos algunos aspectos sobre la dinámica de sistemas cuánticos correlacionados de muchos cuerpos . Específicamente, estudiamos la evolución temporal en un protocolo de cambio súbito que conserva el espectro de entrelazamiento de una bipartición. Consideramos la ruptura de una cadena de Ising en dos cadenas independientes y lo comparamos con la unión de dos cadenas, la cual no conserva el espectro de entrelazamiento. Estos dos cambios abruptos son localmente y globalmente distinguibles. Nuestro resultado sugiere que la mencionada conservación juega un papel fundamental en la dinámica fuera de equilibrio y en el consiguiente equilibrio.
Simonet, Juliette. "Optical traps for Ultracold Metastable Helium atoms." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://tel.archives-ouvertes.fr/tel-00651592.
Full textGhazanfari, Nader. "Rapidly Rotating Ultracold Atoms In Harmonic Traps." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613282/index.pdf.
Full textWest, Adam Daniel. "Interfacing ultracold atoms with nanomagnetic domain walls." Thesis, Durham University, 2012. http://etheses.dur.ac.uk/3588/.
Full textFletcher, Ben. "A rotating optical lattice for ultracold atoms." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504342.
Full textChen, Ruiping. "Laser cooling of atoms for ultracold cooling." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.479242.
Full textWu, Cheng-Hsun Ph D. Massachusetts Institute of Technology. "Strongly interacting quantum mixtures of ultracold atoms." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83817.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 198-202).
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.
by Cheng-Hsun Wu.
Ph.D.
Petrescu, Alexandru. "Topological phases with ultracold atoms and photons." Palaiseau, Ecole polytechnique, 2015. https://theses.hal.science/tel-01208205/document.
Full textWe propose theoretical models that support topological phases and which are relevant to current experiments on lattices hosting photonic modes or ultracold atoms. In the first part of this thesis, we introduce a topological phase on a Kagom ́e lattice whose degrees of freedom are photons. In that context, we discuss two protocols to access the local Berry curvature and the Chern number of Bloch bands from semiclassical dynamics of wavepackets. Secondly, we obtain the phase diagram for bosons at unit filling with repulsive on–site interactions whose kinetic term corresponds to a Chern insulator defined on the honeycomb lattice. In the second part, we turn to recently realized quasi one–dimensional lattices, and un- cover their phase diagrams, comprising low–dimensional Meissner phases, chiral Mott insulating phases as well as abelian fractional quantum Hall states
Simonet, Juliette. "Optical traps for Ultracold Metestable Helium atoms." Paris 6, 2011. http://www.theses.fr/2011PA066055.
Full textDao, Tung-Lam. "Strongly-correlated ultracold atoms in optical lattices." Palaiseau, Ecole polytechnique, 2008. http://www.theses.fr/2008EPXX0023.
Full textKuzmin, Stanislav Gennadyevich. "Ultracold plasmas and guiding center drift atoms /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3138836.
Full textLiu, Ivan Chen-Hsiu. "Ultracold Rydberg Atoms in Structured and Disordered Environments." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1231945394343-32656.
Full textNakagawa, Masaya. "Kondo Effect and Topological Phenomena in Ultracold Atoms." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225388.
Full textGildemeister, Marcus. "Trapping ultracold atoms in time-averaged adiabatic potentials." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:0572480a-9114-426e-b853-b6be30c7594e.
Full textJendrzejewski, Fred. "Quantum transport of ultracold atoms in disordered potentials." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00809290.
Full textLiu, Ivan Chen-Hsiu. "Ultracold Rydberg Atoms in Structured and Disordered Environments." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A23624.
Full textHan, Li. "Spin-orbit coupled ultracold fermions." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52314.
Full textHauke, Philipp Hans-Jürgen. "Quantum simulations with ultracold atoms: beyond standard optical lattices." Doctoral thesis, Universitat Politècnica de Catalunya, 2013. http://hdl.handle.net/10803/117209.
Full textRigol, Madrazo Marcos. "Numerically exact studies of ultracold atoms on optical lattices." [S.l. : s.n.], 2004. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11380462.
Full textBöhi, Pascal Alexander. "Coherent manipulation of ultracold atoms with microwave near-fields." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-120953.
Full textMahnke, Jan [Verfasser]. "A continuously pumped reservoir of ultracold atoms / Jan Mahnke." Hannover : Technische Informationsbibliothek (TIB), 2015. http://d-nb.info/1084239477/34.
Full textVaucher, Benoit. "Theory and applications of ultracold atoms in optical superlattices." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:2ad34b21-6f09-4d96-8750-7ee49a5a7e32.
Full textAidelsburger, Monika. "Artificial gauge fields with ultracold atoms in optical lattices." Diss., Ludwig-Maximilians-Universität München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-181480.
Full textThis thesis reports on the generation of artificial magnetic fields with ultracold atoms in optical lattice potentials using laser-assisted tunneling, as well as on the first Chern-number measurement in a non-electronic system. The high experimental controllability of cold atoms in optical lattices makes them suitable candidates to study condensed matter Hamiltonians, where the atoms play the role of the electrons. However, the observation of magnetic field effects in these systems is challenging because the atoms are charge neutral and do not experience a Lorentz force. In the context of this thesis a new experimental technique for the generation of effective magnetic fields with laser-assisted tunneling was demonstrated, which mimics the physics of charged particles in real magnetic fields. The applied laser beams create a periodic on-site modulation whose phase depends on the position in the lattice and leads to complex tunnel couplings. An atom that hops around a closed loop in this system picks up a non-zero phase, which is reminiscent of the Aharonov-Bohm phase acquired by a charged particle in a magnetic field. The corresponding time-dependent Hamiltonian is typically described in terms of an effective time-independent Floquet Hamiltonian. In this work a theoretical description of the underlying full-time dynamics that occurs within one driving period and goes beyond the simple time-independent picture is presented. In the experiment the laser-assisted-tunneling method was implemented for staggered as well as uniform flux distributions, where the latter is a realization of the Harper-Hofstadter model for a flux Phi=pi/2 per lattice unit cell. By exploiting an additional pseudo-spin degree of freedom the same experimental setup led to the observation of the spin Hall effect in an optical lattice. Using the unique experimental detection and manipulation techniques offered by a two-dimensional bichromatic superlattice potential the strength of the artificial magnetic field and its spatial distribution could be determined through the observation of quantum cyclotron orbits on the level of isolated four-site square plaquettes. The band structure in the presence of a uniform magnetic field is topologically non-trivial and is characterized by the Chern number, a 2D topological invariant, which is at the origin of the quantized Hall conductance observed in electronic systems. In order to probe the topology of the bands the techniques mentioned above were refined by developing a new all-optical laser-assisted tunneling setup, which enabled the first experimental determination of the Chern number in a non-electronic system. The presented measurements and techniques offer a unique setting to study the properties of topological systems with ultracold atoms. All experimental techniques that were developed in the context of this thesis with bosonic atoms can be directly applied to fermionic systems.
Ronzheimer, Jens Philipp. "Non-equilibrium dynamics of ultracold atoms in optical lattices." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-168143.
Full textThe field of non-equilibrium dynamics of strongly correlated quantum systems encompasses some of the most interesting questions about quantum mechanical behavior, but is particularly challenging for established numerical methods. However, recent advances in the experimental control over certain quantum mechanical systems have paved the way towards the quantum simulation of dynamics previously beyond the reach of theoretical investigations. Among the most successful candidates for the implementation of quantum simulators are ultracold atoms in optical lattices, which combine an excellent control over the Hamiltonians governing their evolution with a multitude of methods to measure a diverse range of observables. In our experiments, we use ultracold 39K atoms in blue-detuned optical lattices to implement Bose-Hubbard systems. Employing optical dipole potentials to adjust the external confinement as well as Feshbach resonances to change the interaction strength between the atoms, we are able to control all parameters of the Bose-Hubbard Hamiltonian individually and in real-time, which makes our setup particularly well suited to investigate the time evolution of non-equilibrium systems in a wide range of parameter regimes. Our main experimental results are concerned with the expansion dynamics in homogeneous Hubbard systems. We create initial states of localized atoms in a deep lattice, described by a product of Fock states with no more than one atom per lattice site. These atoms are released into homogeneous lattices by simultaneous quantum quenches in the external confinement as well as the tunneling coupling along the expansion directions. We find that both dimensionality and interaction strength crucially influence the non-equilibrium dynamics. While the atoms expand ballistically in all integrable limits of the Bose-Hubbard model, deviations from these limits dramatically suppress the expansion and lead to the appearance of almost bimodal cloud shapes, indicating diffusive dynamics in the center surrounded by ballistic wings. For strongly interacting bosons, we observe a dimensional crossover of the dynamics from ballistic in the one-dimensional hard-core case to diffusive in two dimensions, as well as a strong suppression of the expansion dynamics upon introducing higher occupancies into the initial state. Furthermore, we investigate the fast relaxation of the system after the sudden quenches and observe a buildup of higher occupancies on a timescale of less than a tunneling time, indicative of local relaxation to quasi-equilibrium values. Finally, we also study the evolution of the quasimomentum distribution of expanding 1D hard-core bosons, which is predicted to acquire sharp peaks at finite quasimomenta while the system undergoes a transient dynamical quasi-condensation. We do observe the formation of a non-thermal quasimomentum distribution with peaks at the correct quasimomenta. However, these peaks are much broader than those predicted by theory. Thus, we discuss multiple possible effects that could hinder the formation or detection of quasi-condensation, as well as methods to experimentally investigate and mitigate these issues.
Pritchard, Matthew J. "Manipulation of ultracold atoms using magnetic and optical fields." Thesis, Durham University, 2006. http://etheses.dur.ac.uk/2373/.
Full textBlackley, Caroline Laura-Anne. "Ultracold scattering of alkali-metal atoms in magnetic fields." Thesis, Durham University, 2015. http://etheses.dur.ac.uk/11202/.
Full text