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1
Golz, Marcel. "Parametric quantum electrodynamics." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/19776.
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In dieser Dissertation geht es um Schwinger-parametrische Feynmanintegrale in der Quantenelektrodynamik. Mittels einer Vielzahl von Methoden aus der Kombinatorik und Graphentheorie wird eine signifikante Vereinfachung des Integranden erreicht. Nach einer größtenteils in sich geschlossenen Einführung zu Feynmangraphen und -integralen wird die Herleitung der Schwinger-parametrischen Darstellung aus den klassischen Impulsraumintegralen ausführlich erläutert, sowohl für skalare Theorien als auch Quantenelektrodynamik. Es stellt sich heraus, dass die Ableitungen, die benötigt werden um Integrale aus der Quantenelektrodynamik in ihrer parametrischen Version zu formulieren, neue Graphpolynome enthalten, die auf Zykeln und minimalen Schnitten (engl. "bonds") basieren. Danach wird die Tensorstruktur der Quantenelektrodynamik, bestehend aus Dirac-Matrizen und ihren Spuren, durch eine diagrammatische Interpretation ihrer Kontraktion zu ganzzahligen Faktoren reduziert. Dabei werden insbesondere gefärbte Sehnendiagramme benutzt. Dies liefert einen parametrischen Integranden, der über bestimmte Teilmengen solcher Diagramme summierte Produkte von Zykel- und Bondpolynomen enthält. Weitere Untersuchungen der im Integranden auftauchenden Polynome decken Verbindungen zu Dodgson- und Spannwaldpolynomen auf. Dies wird benutzt um eine Identität zu beweisen, mit der sehr große Summen von Sehnendiagrammen in einer kurzen Form ausgedrückt werden können. Insbesondere führt dies zu Aufhebungen, die den Integranden massiv vereinfachen.<br>This thesis is concerned with the study of Schwinger parametric Feynman integrals in quantum electrodynamics. Using a variety of tools from combinatorics and graph theory, significant simplification of the integrand is achieved. After a largely self-contained introduction to Feynman graphs and integrals, the derivation of the Schwinger parametric representation from the standard momentum space integrals is reviewed in full detail for both scalar theories and quantum electrodynamics. The derivatives needed to express Feynman integrals in quantum electrodynamics in their parametric version are found to contain new types of graph polynomials based on cycle and bond subgraphs. Then the tensor structure of quantum electrodynamics, products of Dirac matrices and their traces, is reduced to integer factors with a diagrammatic interpretation of their contraction. Specifically, chord diagrams with a particular colouring are used. This results in a parametric integrand that contains sums of products of cycle and bond polynomials over certain subsets of such chord diagrams. Further study of the polynomials occurring in the integrand reveals connections to other well-known graph polynomials, the Dodgson and spanning forest polynomials. This is used to prove an identity that expresses some of the very large sums over chord diagrams in a very concise form. In particular, this leads to cancellations that massively simplify the integrand.
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Viehmann, Oliver. "Multi-qubit circuit quantum electrodynamics." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-160998.
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Habibian, Hessam. "Cavity Quantum Electrodynamics with Ultracold Atoms." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/120180.
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Die vorliegende Arbeit befasst sich mit der Wechselwirkung ultrakalter Atome mit
der Mode eines optischen Resonators hoher Güte. Die Atome sind dabei in einem
periodischen Potenzial gefangen, dessen Periodizität nicht kommensurabel mit der
Wellenlänge des Resonators ist. Ein Laser regt die Atome an und sie streuen Photonen
in die Resonatormode, wobei die Emission inkohärent ist, falls die Laue-
Bedingung nicht erfüllt ist. Dieser Fall wird betrachtet und es werden Bedingungen
ermittelt, für welche nichtlineare optische Prozesse auftreten können. Die Eigenschaften
des Lichtes werden untersucht, wenn sich das System entweder wie ein
parametrischer Verstärker verhält oder wie eine Lichtquelle mit "Antibunching"-
Statistik. Weiterhin kann eine stationäre Verschränkung zwischen Licht und Spinwellen
der Atome erzeugt werden. Im zweiten Teil wird die Situation betrachtet,
in der die Nullpunktsbewegung der Atome für die Atom-Licht-Wechselwirkung relevant
ist. Für große Parameterbereiche zeigen numerische Berechnungen, dass die
Rückwirkung des Resonators die Formierung eines lokalen Schachbrettmusters in
der atomaren Dichteverteilung erzeugt. Die einzelnen Atomgruppe dieses Musters
stehen zueinander in fester Phasenbeziehung, was zur Erhöhung der Zahl der Resonatorphotonen
führt.<br>In 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.
4
Kannan, Bharath. "Waveguide quantum electrodynamics with superconducting qubits." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120400.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 85-87).<br>Experiments in quantum optics have long been implemented with atoms in 3D free space or with atoms interacting with cavities. Over the past decade, the field of microwave quantum optics using superconducting circuits has gained a tremendous amount of attention. In particular, the confinement of photonic modes to 1D enables a new parameter regime of strong interactions between qubits and open waveguides. In these setups, known as waveguide quantum electrodynamics (WQED), superconducting qubits interact with a continuum of propagating photonic modes. In this thesis, we will explore the physics of WQED devices that consist of multiple qubits and their potential application to quantum information and simulation.<br>by Bharath Kannan.<br>S.M.
5
Kohler, Shane Jerome. "Non-linear effects in quantum electrodynamics." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5279.
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Diniz, Igor. "Quantum electrodynamics in superconducting artificial atoms." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENY048/document.
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This thesis focuses on two problems in circuit quantum electrodynamics. We first investigate theoretically the coupling of a resonator to a continuous distribution of inhomogeneously broadened emitters. Studying this formalism is strongly motivated by recent proposals to use collections of emitters as quantum memories for individual excitations. Such systems benefit from the collective enhancement of the interaction strength, while keeping the relaxation properties of a single emitter. We discuss the influence of the emitters inhomogeneous broadening on the existence and on the coherence properties of the polaritonic peaks. We find that their coherence depends crucially on the shape of the distribution and not only on its width. Taking into account the inhomogeneous broadening allows to simulate with a great accuracy a number of pioneer experimental results on a ensemble of NV centers. The modeling is shown to be a powerful tool to obtain the properties of the spin ensembles coupled to a resonator. We also suggest an original Josephson qubit readout method based on a dc-SQUID with high loop inductance. This system supports a diamond-shape artificial atom where we define logical and ancilla qubits coupled through a cross-Kerr like term. Depending on the logical qubit state, the ancilla is resonantly or dispersively coupled to the resonator, leading to a large contrast in the transmitted microwave signal amplitude. Simulations show that this original method can be faster and have higher fidelity than methods currently used in circuit QED<br>Cette thèse porte sur deux problèmes théoriques d'électrodynamique quantique en circuits supraconducteurs. Nous avons d'abord étudié les conditions d'obtention du couplage fort entre un résonateur et une distribution continue d'émetteurs élargie de façon inhomogène. Le développement de ce formalisme est fortement motivé par les récentes propositions d'utiliser des ensembles de degrés de liberté microscopiques pour réaliser des mémoires quantiques. En effet, ces systèmes bénéficient du couplage collectif au résonateur, tout en conservant les propriétés de relaxation d'un seul émetteur. Nous discutons l'influence de l'élargissement inhomogène sur l'existence et les propriétés de cohérence des pics polaritoniques obtenus dans le régime de couplage fort. Nous constatons que leur cohérence dépend de façon critique de la forme de la distribution et pas uniquement de sa largeur. En tenant compte de l'élargissement inhomogène, nous avons pu simuler avec une grande précision de nombreux résultats expérimentaux pionniers sur un ensemble de centres NV. La modélisation s'est révélée un outil puissant pour obtenir les propriétés des ensembles de spins couplés à un résonateur. Nous proposons également une méthode originale de mesure de l'état de qubits Josephson fondée sur un SQUID DC avec une inductance de boucle élevée. Ce système est décrit par un atome artificiel avec des niveaux d'énergie en forme de diamant où nous définissons les qubits logique et ancilla couplés entre eux par un terme Kerr croisé. En fonction de l'état du qubit logique, l'ancilla est couplée de manière résonante ou dispersive au résonateur, ce qui provoque un contraste important dans l'amplitude du signal micro-onde transmis par le résonateur. Les simulations montrent que cette méthode originale peut être plus rapide et peut aussi avoir une plus grande fidélité que les méthodes actuellement utilisées dans la communauté des circuits supraconducteurs
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Грицунов, А. В., И. Н. Бондаренко, А. Б. Галат, О. В. Глухов, and А. Г. Пащенко. "On the quantum electrodynamics of nanosystems." Thesis, Kharkiv, bookfabrik, 2019. http://openarchive.nure.ua/handle/document/10408.
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Problems of quantum dynamics of nanoobjects essential for development of new nanoelectronic systems are discussed. According to the theory of natural oscillatory systems (NOSs), “interaction” between the objects is interpreted as a quantum-dynamic phenomenon meaning a stable trend arising from the quantum chaos. As an opposite, “interchange” is denominated as the permanent stochastic exchange with action quanta between different NOSs in 4D spacetime, being the physical base of the quantum chaos. The Tetrode-Wheeler-Feynman’s concept of “direct interparticle action” is reconciled with both the quantum radiation-absorption and the Coulomb interaction. A conservation law for the action is supposed as a necessary condition for the momentum-energy conservation. The “classic” conservation law for the momentum-energy is considered as derivative, being valid for the momentum as well as some physical value that is an integral over 3D space from a linear combination of stress-energy tensor principal diagonal terms. Such redefinition enables the unconditional quantization of the energy unlike “orthodox” quantum theory.
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Jeantet, Adrien. "Cavity quantum electrodynamics with carbon nanotubes." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC010/document.
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Les nanotubes de carbone sont largement étudiés pour leurs propriétés mécaniques et électroniques étonnantes. Optiquement, ils sont d'excellents candidats pour les sources à un seul photon à la demande car ils peuvent être excités électriquement et ils peuvent émettre une lumière dégroupée à température ambiante dans les bandes de télécommunications. Cependant, leur efficacité d'émission est faible, les origines de l'émission restent peu claires et la forme spectrale de leur photoluminescence est compliquée.Dans ce travail, nous construisons une configuration originale combinant un microscope confocal et une micro-cavité à base de fibres optiques qui est à la fois spatialement et spectralement réglable. Avec ce dispositif, nous avons observé l'apparition des effets de l'électrodynamique quantique en cavité en analysant l'évolution du couplage dipôle-cavité en fonction du volume de la cavité. Nous avons obtenu une forte accélération du taux d'émission spontanée, grâce à des facteurs Purcell supérieurs à 100. L'efficacité effective associée de la source atteint jusqu'à 50%, conduisant à une luminosité jusqu'à 10%, tout en conservant d'excellentes caractéristiques de dégroupement.Nous observons l'effet du couplage de la cavité en fonction du désaccord de la cavité et développons un modèle pour tenir compte des émetteurs soumis au couplage exciton-phonon en présence d'une cavité. Nous montrons que notre source de photons uniques est accordable sur une gamme de fréquences plus de cent fois supérieure à la largeur spectrale de la cavité, ouvrant ainsi la voie à un multiplexage étendu.Un renforcement supplémentaire du couplage peut ouvrir la voie à la très riche physique des polaritons de cavité unidimensionnels. Inversement, les polaritons de cavité pourraient être un outil pour mieux comprendre la diffusion et les propriétés de localisation des excitons dans les nanotubes de carbone. Enfin, la configuration initiale ici est extrêmement polyvalente et pourrait être utilisée pour coupler d'autres types d'émetteurs, comme les nano-diamants ou les molécules<br>Carbon nanotubes are extensively investigated for their amazing mechanical and electronic properties. Optically, they are excellent candidates for on-demand single-photon sources because they can be electrically excited and they can emit anti-bunched light at room temperature in the telecoms bands. However, their emission efficiency is low, its origins remain unclear and the spectral shape of their photoluminescence is complicated. In this work, we build an original setup combining a confocal microscope and a fiber based micro-cavity which is both spatially and spectrally tunable. With this device, we observed the rise of cavity quantum electrodynamics effects by analyzing the evolution of the dipole-cavity coupling as a function of the cavity volume. We obtained a strong acceleration of the spontaneous emission rate, due to Purcell factors above 100. The associated effective efficiency of the source reaches up to 50%, leading to a brightness of up to 10%, while keeping excellent anti-bunching features. We observe the effect of the cavity coupling as a function of the cavity detuning, and develop a model to account for emitters undergoing exciton-phonon coupling in the presence of a cavity. We show that our single-photon source is tunable on a range of frequencies more than a hundred times higher than the cavity spectral width, opening the way to extensive multiplexing. Further strengthening of the coupling may open the way to the very rich physics of one-dimensional cavity polaritons. And conversely, cavity polaritons could be a tool to understand better the diffusion, and localization properties of excitons in carbon nanotubes. Finally, the original setup build here is extremely versatile and could be used to coupled other types of emitters, such as nano-diamonds or molecules
9
Helmer, Ferdinand. "Quantum information processing and measurement in circuit quantum electrodynamics." Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-102919.
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Young, Andrew Buchanan. "Cavity quantum electrodynamics : applications to solid state quantum information." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.720859.
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Hendrickson, Joshua. "Cavity Quantum Electrodynamics with Quantum Dot - Photonic Crystal Nanocavities." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/196032.
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High quality factor, small mode volume photonic crystal cavities and single emitter quantum dots are the topic of this dissertation. They are studied as both a combined system with InAs quantum dots grown in the center of a 2D GaAs photonic crystal slab nanocavity as well as individually. The individual studies are concerned with passive 1D silicon photonic crystal nanobeam cavities and deterministic, site-selectively grown arrays of InAs quantum dots.For the combined system, strong light matter coupling in a quantum dot photonic crystal slab nanocavity is discussed. Vacuum Rabi splitting is seen when the interaction strength exceeds the dissipative processes of the coupled system. In order to increase the probability of a spectral matching between cavity modes and quantum dot transitions, a technique for condensing an inert gas onto a sample is used. This can lead to a spectral tuning of up to 4 nm of the cavity mode with minimal change in the cavity quality factor while maintaining cryogenic temperatures down to 4 K. The effect of a large density of quantum dots within a quantum dot photonic crystal slab nanocavity is also addressed. Gain and absorption effects are found to occur, changing the cavity emission linewidth from that of its intrinsic value, as well as lasing with a low number of quantum dots and with high spontaneous emission coupling factors. Additionally, methods for improving the quality factor of GaAs photonic crystal cavities and better understanding different loss mechanisms are discussed.In the individual studies, the site-selective growth of InAs quantum dots on pre-structured GaAs wafers is shown as a promising method for the eventual deterministic fabrication of photonic crystal cavities to single quantum dots. An in-situ annealing step is used to reduce quantum dot density, helping ensure that dots are not grown in unwanted locations.Given silicon's potential for achieving higher quality factors than its GaAs counterpart, a study of 1D passive silicon photonic crystal nanobeam cavities is carried out. Transmission through a coupled microfiber is used to measure quality factors of the cavities and compared with that of a crossed polarized resonant scattering measurement.
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Özelci, Ersan. "Exploring Fundamental Limits of Quantum Efficiency Measurements Using Quantum Electrodynamics." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/22539.
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Photolumineszenz-Techniken spielen eine wichtige Rolle bei der Charakterisierung verschiedener funktionaler Fluorophore in den Lebens- und Materialwissenschaften, in der Biologie und bis hin zu den Quantentechnologien. Ein entscheidender und wichtiger Parameter für den Vergleich von Fluorophoren ist die Quanteneffizienz, die ein direktes Maß für die Umwandlungseffizienz von absorbierten Photonen in emittierte Photonen darstellt. Diese Größe charakterisiert die Nutzbarkeit von Emittern für Anwendungen in optischen Geräten, Einzelphotonenquellen und im biomedizinischen Bereich. Mehrere Techniken wie optische und photothermische Methoden werden verwendet, um die photolumineszente Quanteneffizienz zu messen, und so die Eignung von Fluorophoren für verschiedene Anwendungen zu bewerten. Quanteneffizienz-Messungen können jedoch eine Herausforderung für hochverdünnte Fluorophore sein, die in dünne Schichten eingebettet sind. Die in dieser Arbeit beschriebene Forschung überwindet die Herausforderungen der Quanteneffizienzmessung durch eine Modifikation der Wechselwirkung zwischen Licht und Umgebung.<br>Photoluminescence techniques play an important role for characterization of various functional fluorophores in the life and material sciences from biology to quantum technologies. A crucial and key parameter for comparing the performance of fluorophores is the photoluminescence quantum efficiency or quantum yield, which presents a direct measure of conversion efficiency of absorbed photons into emitted photons. This quantity characterizes the performance of emitters for applications in optical devices as single photon sources and in the biomedical sector. Several techniques such as optical and photothermal methods are used to measure the photoluminescence quantum efficiency of emitters in various environments and aggregation states. Quantum efficiency measurements can be challenging for fluorophores in solid matrix, in scattering systems and for highly diluted fluorophores embedded to thin films. The research described in this thesis overcomes these challenges by performing quantum efficiency measurement via modifying the spontaneous emission as a fundamental process of light-matter interaction.
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Hauck, John C. "Electrodynamics of accelerated systems /." free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p3101024.
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Baxter, Colin. "Gauge transformations in non-relativistic quantum electrodynamics." Thesis, University of Essex, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292876.
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Lepert, Guillaume. "Integrated optics for coupled-cavity quantum electrodynamics." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11175.
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This thesis reports on the development of an array of plane-concave Fabry-Perot microcavities containing atoms (or other quantum emitters), interconnected by UV-written waveguides on a silica-on-silicon chip. The microcavities are formed by a mirror coated on the end facet of the chip and an array of spherical micromirrors etched on silicon. This is to our knowledge the first attempt at implementing the emerging coupled-cavities QED paradigm. The device we propose possesses a degree of control, flexibility and tuning unmatched in other suggested implementations: The atoms can be manipulated inside the cavity by auxiliary lasers and the cavity-cavity coupling rate as well as the atom-cavity coupling can be tuned. It is highly scalable. Calculation of the complete (classical) optical spectrum of the device is presented. The quantum dynamics that may eventually be observed has also been studied. Waveguide chips containing couplers and phase shifter have been fabricated. We have successfully demonstrated the operation of the elementary sub-systems: the strong optical coupling between a microcavity and a waveguide resonator, and the tunable strong coupling between two evanescently coupled waveguide resonators. No experiments with atoms or other quantum emitters were attempted, because the waveguide propagation loss is so large that no quantum physics can be observed. There is hope that this can be overcome in the future by using other waveguide technologies.
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Walker, Philip. "Radiation and reaction in scalar quantum electrodynamics." Thesis, University of York, 2010. http://etheses.whiterose.ac.uk/996/.
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This thesis is a report of work which develops the study of electromagnetic radiation by accelerating charges in the scalar quantum electrodynamic theory. We investigate aspects of this theory in flat spacetime, and in a class of conformally flat and curved spacetimes. In particular, we show that in flat spacetime, the quantum-theoretic prediction for the emission of energy by the particle, in the limit h-bar tends to 0 and to order e^2 in the coupling constant, may be shown to match the classical calculation. We also calculate the order h-bar correction to this quantity for two specific classes of problem. In the class of conformally flat and curved spacetimes, we compare the change in position due to the radiation reaction with the classical result, and we also consider some of the one-loop corrections to the theory. We show that as h-bar tends to 0, the conformally flat result and the classical result match, but that in that limit the general spacetime results differ.
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Barlow, Thomas Michael. "Cavity quantum electrodynamics of fibre-cavity networks." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/12646/.
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Quantum mechanics, despite its abstract and unintuitive nature, is increasingly used in real-life applications. This thesis explores the current status of cavity quantum electrodynamics and its role in applications of quantum optics to quantum technologies. Various approaches to the treatment of optical cavities are discussed, with particular focus on a treatment in terms of cavities as linear optical devices, with a nonlinearity introduced by an atom, molecule, quantum dot etc in the cavity. Open quantum systems such as optical cavities coupled to a free external radiation field can be described by a quantum master equation. This thesis develops a description of such a system in which the Hamiltonian describes the coherent evolution of light inside the cavity, and the damping term describes the leaking of light out of the cavity mirrors. The goal of this approach is to describe couple networks of optical cavities in which information is transferred across the network coherently.
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Ho, Andy C. T. "Imaginary charge quantum electrodynamics : a running coupling analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0005/NQ34551.pdf.
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Nadeau, Raymond. "Two-loop effective potential of supersymmetric quantum electrodynamics." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75872.
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The formalism of effective potential method is first studied for usual field theory and extended to supersymmetric field theory. The specific case of supersymmetric quantum electrodynamics is then introduced. The superfields are shifted as required by Weinberg's method for the evaluation of effective potentials and superpropagators are derived with the method developed by Helayel-Neto for cases where supersymmetry is explicitly broken. Then, the one and two loop corrections to the effective potential may be calculated. These corrections are seen to be complex everywhere but at the minimum of the potential. Tile theory is then renormalized in a modified minimal substraction scheme and a finite expression is finally obtained for the effective potential. Thereon, the renormalized coupling constant and the $ beta$-function are calculated.
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Braverman, Boris. "Cavity quantum electrodynamics with ensembles of ytterbium-171." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120364.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2018.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (pages 313-328).<br>In this thesis, I present the realization of a system applying the tools of cavity quantum electrodynamics to an atomic optical lattice clock. We design and implement a unique experimental cavity structure, with a small radius of curvature mirror on one side and a large mirror on the other side. With this structure, we are able to probe ytterbium-171 atoms in both the weak and strong coupling regimes of cavity quantum electrodynamics. This asymmetric micromirror structure simultaneously offers strong light-atom coupling, mechanical robustness, and excellent access to a large cavity volume. We develop a simple but accurate model for strong light-atom interactions in our system, which allows us to predict the performance of both cavity-assisted quantum non demolition measurements of the atomic state, and the back-action of the probing light onto the atomic state. We find theoretically, and confirm experimentally, that probing the atom-cavity system with two frequencies at the vacuum Rabi peaks of a system with strong collective light-atom coupling generates the largest possible entanglement between the probing light and the atomic state. With this scheme, we demonstrate atomic number measurements within a factor of 2 of the quantum Fisher information limit. By using the quantum back-action of the probing light on the atomic ensemble, we perform squeezing by cavity feedback. We produce states with -11±1 dB of variance squeezing and 14±1 dB of anti squeezing. Using theoretical simulations, we show that states with near-unitary squeezing offer significant advantages for improving atomic clocks compared to previous work. The ability to load large atomic ensembles in the strong coupling regime in our system offers several routes to the generation of highly entangled non-Gaussian quantum states. Such states can be produced by heralded measurements, or by global atom-atom interactions based on unitary spin squeezing. Altogether, we realize a system of unprecedented versatility and great potential for performing a large variety of hybrid atomic clock and cavity QED experiments.<br>by Boris Braverman.<br>Ph. D.
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Golyk, Vladyslav Alexander. "Non-equilibrium fluctuation induced-phenomena in quantum electrodynamics." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91076.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2014.<br>138<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 120-129).<br>We study fluctuation-induced phenomena in systems out of thermal equilibrium, resulting from the stochastic nature of quantum and thermal fluctuations of electromagnetic currents and waves. Specifically, we study radiative heat transfer and Casimir forces by applying the scattering formalism that expresses results solely in terms of the classical scattering matrices of the objects. For example, we obtain exact formulas for the heat radiation emitted by long cylindrical objects, as well as for Casimir forces that arise between them. We apply our results to explore the dependence of these phenomena on size and material properties of cylinders. While the scattering formalism is very general and technically can be employed for arbitrary shapes, in practice it is very time-consuming to apply it to the most experimentally-relevant and complex case of objects at close proximity. We examine easier ways to compute the heat transfer in such case. In particular, we develop a small distance expansion for the heat transfer between gently curved objects, in terms of the ratio of distance to radius of curvature. This expansion allows us to rigorously justify the widely used approach of "proximity transfer approximation", and to quantify corrections to it in the limit of small separation. Moreover, we study the role of surface roughness, and show that it may change the distance dependence of the heat transfer as well as Casimir forces between curved objects at proximity. Finally, as an alternative approach we construct general Green-Kubo relations that connect radiative heat transfer, non-equilibrium Casimir forces and vacuum friction between arbitrary objects to fluctuations in equilibrium which may be easier to consider from the perspective of experiment and simulations.<br>by Vladyslav Alexander Golyk.<br>Ph. D.
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Holland, Eric T. "Cavity State Reservoir Engineering in Circuit Quantum Electrodynamics." Thesis, Yale University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10012490.
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<p> Engineered quantum systems are poised to revolutionize information science in the near future. A persistent challenge in applied quantum technology is creating controllable, quantum interactions while preventing information loss to the environment, decoherence. In this thesis, we realize mesoscopic superconducting circuits whose macroscopic collective degrees of freedom, such as voltages and currents, behave quantum mechanically. We couple these mesoscopic devices to microwave cavities forming a cavity quantum electrodynamics (QED) architecture comprised entirely of circuit elements. This application of cavity QED is dubbed Circuit QED and is an interdisciplinary field seated at the intersection of electrical engineering, superconductivity, quantum optics, and quantum information science. Two popular methods for taming active quantum systems in the presence of decoherence are discrete feedback conditioned on an ancillary system or quantum reservoir engineering. Quantum reservoir engineering maintains a desired subset of a Hilbert space through a combination of drives and designed entropy evacuation. Circuit QED provides a favorable platform for investigating quantum reservoir engineering proposals. A major advancement of this thesis is the development of a quantum reservoir engineering protocol which maintains the quantum state of a microwave cavity in the presence of decoherence. This thesis synthesizes strongly coupled, coherent devices whose solutions to its driven, dissipative Hamiltonian are predicted a <i>priori</i>. This work lays the foundation for future advancements in cavity centered quantum reservoir engineering protocols realizing hardware efficient circuit QED designs. </p>
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Zhang, Ou. "Effective field theories for quantum chromo- and electrodynamics." Thesis, The University of Arizona, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10247445.
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<p> Effective field theories (EFTs) provide frameworks to systematically improve perturbation expansions in quantum field theory. This improvement is essential in quantum chromodynamics (QCD) predictions, both at low energy in the description of low momentum hadron-hadron scattering and at high energy in the description of electron-positron, proton-proton, proton-electron collisions. It is also important in quantum electrodynamics (QED), when electrons interact with a high-intensity, long-wavelength classical field. I introduce the principles and methods of effective field theory and describe my work in three EFTs: First, in the perturbative QCD region, I use soft collinear effective theory (SCET) to prove that strong interaction soft radiation is universal and to increase the QCD accuracy to next-to-next-to-next-to leading logarithm order for new particle searches in hadron colliders. I also compute a new class of non-perturbative, large logarithmic enhancement arising near the elastic limits of deep inelastic scattering and Drell-Yan processes. Second, in the QCD confinement region, I use heavy hadron chiral perturbation theory to study near-threshold enhancements in the scattering of <i>D</i> and π mesons near the threshold for the excited <i>D</i>-meson state, <i> D*,</i> as well as in the scattering of <i>D</i> and <i> D*</i> mesons near the threshold for the exotic hadron X(3872). This work provides a clear picture of the hadronic molecule X(3872) and more profound understanding of the nuclear force between hadrons. Finally, inspired by SCET, I construct a new electron-laser effective field theory to describe highly-relativistic electrons traveling in strong laser fields, extract the universal distribution of electrons in strong electromagnetic backgrounds and its evolution in energy from the separated momentum scales of emitted photons and classical radiation, and predict the rate of wide angle photon emission. I conclude with limitations of EFT methods and some perspectives on what new work may be achieved with these EFTs.</p>
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Zhang, Ou, and Ou Zhang. "Effective Field Theories for Quantum Chromo- and Electrodynamics." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621825.
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Effective field theories (EFTs) provide frameworks to systematically improve perturbation expansions in quantum field theory. This improvement is essential in quantum chromodynamics (QCD) predictions, both at low energy in the description of low momentum hadron-hadron scattering and at high energy in the description of electron-positron, proton-proton, proton-electron collisions. It is also important in quantum electrodynamics (QED), when electrons interact with a high-intensity, long-wavelength classical field. I introduce the principles and methods of effective field theory and describe my work in three EFTs: First, in the perturbative QCD region, I use soft collinear effective theory (SCET) to prove that strong interaction soft radiation is universal and to increase the QCD accuracy to next-to-next-to-next-to leading logarithm order for new particle searches in hadron colliders. I also compute a new class of non-perturbative, large logarithmic enhancement arising near the elastic limits of deep inelastic scattering and Drell-Yan processes. Second, in the QCD confinement region, I use heavy hadron chiral perturbation theory to study near-threshold enhancements in the scattering of 𝐷 and 𝜋 mesons near the threshold for the excited 𝐷-meson state, 𝐷*, as well as in the scattering of 𝐷 and 𝐷* mesons near the threshold for the exotic hadron X(3872). This work provides a clear picture of the hadronic molecule X(3872) and more profound understanding of the nuclear force between hadrons. Finally, inspired by SCET, I construct a new electron-laser effective field theory to describe highly-relativistic electrons traveling in strong laser fields, extract the universal distribution of electrons in strong electromagnetic backgrounds and its evolution in energy from the separated momentum scales of emitted photons and classical radiation, and predict the rate of wide angle photon emission. I conclude with limitations of EFT methods and some perspectives on what new work may be achieved with these EFTs.
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Cardoso, Lucas Tavares. "Towards renormalizability of string-localized massive quantum electrodynamics." Universidade Federal de Juiz de Fora (UFJF), 2017. https://repositorio.ufjf.br/jspui/handle/ufjf/5621.
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Previous issue date: 2017-08-03<br>CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>A construção de campos com localização em cordas foi realizada rigorosamente há pouco mais de uma década. Nesta abordagem, os campos são operadores em algum espaço de Hilbert, e portanto não há graus de liberdade não-físicos tais como "ghosts". Além de permitir a construção de campos carregados inteiramente num espaço espaço de Hilbert, os campos com localização em cordas exibem um bom comportamento no regime ultravioleta e, entre outras características, são possíveis candidatos para descreverem consistentemente a matéria escura. No intuito de obter uma prova da renormalizabilidade em modelos perturbativos no esquema de Epstein-Glaser com campos quânticos localizados em cordas, é necessário evidenciar a liberdade que se tem ao definir produtos temporalmente ordenados do Lagrangeano de interação. Este trabalho proporciona um primeiro passo significativo nesta direção. O problema básico é a presença de um conjunto aberto de n-uplas de cordas que não podem ser cronologicamente ordenadas. Nós resolvemos este problema ao mostrar que quase todas (i.e. exceto num subconjunto de medida nula) tais configurações de cordas podem ser dissecadas num número finito de pedaços, os quais por sua vez podem ser cronologicamente ordenados. Com isso, tem-se que o produto temporalmente ordenado de fatores lineares de campos está fixo fora de um conjunto de medida nula de configurações de cordas. A construção do ordenamento temporal geométrico de cordas é feita de modo a servir para o estudo da renormalizabilidade de quaisquer teorias quânticas de campos com localização em cordas.<br>The construction of string-localized fields was rigorously accomplished a little over a decade ago. In this approach, the fields are operators in some Hilbert space, and therefore there are no unphysical degrees of freedom such as ghosts. In addition to allowing the construction of charged fields entirely in a Hilbert space, the string-localized fields exhibit, in general, a good behavior in the ultraviolet regime and, among other features, the class (representation) of string-localized fields with m = 0 and s = oo are possible candidates to consistently describe dark matter. In order to obtain a proof of renormalizability of perturbative models in the Epstein—Glaser scheme with string-localized quantum fields, one needs to know what freedom one has to define time-ordered products of the interaction Lagrangian. This work provides a first significant step in that direction. The basic issue is the presence of an open set of n-tuples of strings which cannot be chronologically ordered. We resolve it by showing that almost all (i.e. outside a null set) such string configurations can be dissected into finitely many pieces which can indeed be chronologically ordered. This fixes the time-ordered products of linear field factors outside a nullset of string configurations. The construction of the geometric time ordering of strings is realized in such a way that it will serve to study the renormalizability of any quantum field theories with string-localized fields
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Stokes, Adam. "On gauge freedom and subsystems in quantum electrodynamics." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/6833/.
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I analyse different decompositions of composite light-matter systems into constituent subsystems. I show that given a single description of a composite atomfield system, many different decompositions into “atom” and “field” subsystems can be made. I show that these decompositions are generally physically inequivalent, and that they can be understood as corresponding to different choices of gauge. I discuss some of the implications this has for the ontology of QED, and find experimental signatures that could be used to distinguish between different theoretical subsystem decompositions.
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Flatten, Lucas Christoph. "Quantum electrodynamics of semiconducting nanomaterials in optical microcavities." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:a5f4797f-ea23-49e4-bd1e-2483154508d6.
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Semiconducting nanocrystals in open-access microcavities are promising systems in which enhanced light-matter interactions lead to quantum effects such as the modulation of the spontaneous emission process and exciton-polariton formation. In this thesis I present improvements of the open cavity platform which serves to confine the electromagnetic field with mode volumes down to the λ<sup>3</sup> regime and demonstrate results in both the weak and strong coupling regimes of cavity quantum electrodynamics with a range of different low-dimensional materials. I report cavity fabrication details allowing a peak finesse of 5 × 10<sup>4</sup> and advanced photonic structures such as coupled cavities in the open cavity geometry. By incorporating two-dimensional materials and nanoplatelets in the cavity I demonstrate the strong coupling regime of light-matter interaction with the formation of exciton-polaritons, quasi-particles composed of both photon and exciton, at room temperature. In the perturbative weak coupling regime I show pronounced modulation of the single-photon emission from CdSe/ZnS quantum dots and the two-dimensional material WSe<sub>2</sub> and demonstrate Purcell enhancement of the spontaneous emission rate by factors of 2 at room temperature and 8 at low temperature. The findings presented in this thesis pave the way to establish open microcavities as a platform for a wide range of applications in nanophotonics and quantum information technologies.
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Rippin, Michael Andrew. "Quantum optics of tailored cavities." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242050.
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Özelci, Ersan [Verfasser]. "Exploring Fundamental Limits of Quantum Efficiency Measurements Using Quantum Electrodynamics / Ersan Özelci." Berlin : Humboldt-Universität zu Berlin, 2021. http://d-nb.info/1229916423/34.
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Brown, Solly. "The photon model of the quantum electromagnetic field /." [St. Lucia, Qld.], 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16777.pdf.
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Chou, Kevin S. "Teleported operations between logical qubits in circuit quantum electrodynamics." Thesis, Yale University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10957321.
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<p> A quantum computer has the potential to efficiently solve problems that are intractable for classical computers. Constructing a large-scale quantum processor, however, is challenging due to errors and noise inherent in real-world quantum systems. One approach to this challenge is to utilize modularity—a pervasive strategy found throughout nature and engineering—to build complex systems robustly. Such an approach manages complexity and uncertainty by assembling small, specialized components into a larger architecture. These considerations motivate the development of a quantum modular architecture, where separate quantum systems are combined via communication channels into a quantum network. In this architecture, an essential tool for universal quantum computation is the teleportation of an entangling quantum gate, a technique originally proposed in 1999 which, until now, has not been realized deterministically, Using the circuit quantum electrodynamics platform, this thesis reports on the experimental demonstration of a teleported controlled-NOT operation made deterministic by utilizing real-time adaptive control. Additionally, we take a crucial step towards implementing robust, error-correctable modules by enacting the gate between logical qubits, encoding quantum information redundantly in the states of superconducting cavities. Such teleported operations have significant implications for fault-tolerant quantum computation, and when realized within a network can have broad applications in quantum communication, metrology, and simulations. Our results illustrate a compelling approach for implementing multi-qubit operations on logical qubits within an error-protected quantum modular architecture.</p><p>
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Nissen, Felix Beat Fabian. "Effects of dissipation on collective behaviour in circuit quantum electrodynamics." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648225.
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Tignone, Edoardo. "Cavity quantum electrodynamics : from photonic crystals to Rydberg atoms." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF008/document.
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Dans le premier chapitre de la thèse, nous étudions la possibilité d’améliorer le couplage opto- mechanique photon-phonon entre le mode de résonance d’une cavité Fabry-Pérot de haute finesse et les vibrations mécaniques des éléments diélectriques (membranes) à l’intérieur de la cavité. En introduisant un défaut quadratique dans la disposition des membranes, nous montrons que le deux couplages (linéaire et quadratique) augmentent. Enfin, nous proposons un modèle très simple avec lequel on cherche à simuler un cristal photonique quasipériodique. Dans le deuxième chapitre de cette thèse, nous présentons nos résultats de recherche sur le transport d’excitons à travers une cavité visant à augmenter l’efficacité du transport. Le modèle que l’on étudie est une chaîne unidimensionnelle d’atomes froids comprenant chacun deux niveaux énergétiques. Grâce au couplage entre exciton et photon, ces deux quanta s’hybrident et forment deux branches de polariton à l’intérieur de la cavité. Nous avons observé qu’à résonance avec un des deux modes de polariton, on peut transmettre l’exciton via le mode polaritonique dans un temps très court. En outre, le désordre n’affecte la propagation excitonique que de façon algébrique. Dans le troisième chapitre de cette thèse, nous présentons nos résultats de recherche sur la réalisa- tion d’interactions entre photons grâce à la médiation d’atomes ultrafroids piégés dans un réseaux optique unidimensionnelle et placés à l’intérieur d’une fibre à cristaux photoniques. Nous avons détecté un régime dans lequel on peut réaliser le “bunching” photon-photon.Dans le quatrième et dernière chapitre de cette thèse, nous étendons les résultats du chapitre précédent aux atomes de Rydberg<br>In the first chapter of this thesis, we study a quasiperiodic array of dielectric membranes inside a high-finesse Fabry-Pérot cavity. We work within the framework of the transfer matrix formal- ism. We show that, in a transmissive regime, the introduction of a quadratic spatial defect in the membrane positions enhances both the linear and quadratic optomechanical couplings between optical and mechanical degrees of freedom. Finally, we propose a theoretical model to simulate a one-dimensional quasiperiodic photonic crystal. In the second chapter of this thesis, we consider the problem of the transport of an exciton through a one-dimensional chain of two-level systems. We embed the chain of emitters in a transverse optical cavity and we show that, in the strong coupling regime, a ultrafast ballistic transport of the exciton is possible via the polaritonic modes rather than ordinary hopping. Due to the hybrid nature of polaritons, the transport efficiency is particularly robust against disorder and imperfections in the system. In the third chapter of this thesis, we consider an ordered array of cold atoms trapped in an optical lattice inside a hollow-core photonic crystal fiber. We study photon-photon interactions mediated by hard-core repulsion between excitons. We show that, in spite of underlying repulsive interac- tion, photons in the scattering states demonstrate bunching, which can be controlled by tuning the interatomic separation. We interpret this bunching as the result of scattering due to the mismatch of the quantization volumes for excitons and photons, and discuss the dependence of the effect on experimentally relevant parameters. In the fourth chapter of the thesis, we extend the results of the previous chapter to Rydberg atoms
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Dutra, Sergio Mendes. "Generation and detection of fields in cavity quantum electrodynamics." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307569.
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Twining, Carole Janet. "A study of lattice quantum electrodynamics in three dimensions." Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316545.
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Wu, Shin-Tza. "Quantum electrodynamics in front of a dielectric half-space." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624491.
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Wilson, Nicholas. "Dyson-Schwinger equations in quantum electrodynamics at finite temperature." Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/10015.
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The functional integral formulation of finite temperature field theory and its connection to statistical mechanics is reviewed. The one loop contributions to quantum electrodynamics at finite temperature are explicitly calculated. Dyson-Schwinger equations for quantum electrodynamics at finite temperature are constructed and possible methods of solving them are discussed.
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Reid, Benjamin P. L. "Towards cavity quantum electrodynamics and coherent control with single InGaN/GaN quantum dots." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:a8d84318-36a8-455f-a2fa-7fb9c4c738a0.
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Experimental investigations of the optical properties of InGaN/GaN quantum dots are presented. A pulsed laser is used to perform time-integrated and time-resolved microphotoluminescence, photoluminescence excitation, and polarisation-resolved spectroscopy of single InGaN quantum dots under a non-linear excitation regime. The first micro-photoluminescence results from InGaN/GaN quantum dots grown on a non-polar crystal plane (11<sup>-</sup><sub style='position: relative;left: -.4em;'>2</sub>0) are presented. Time-resolved studies reveal an order of magnitude increase in the oscillator strength of the exciton transition when compared to InGaN quantum dots grown on the polar (0001) plane, suggesting a significantly reduced internal electric field in non-polar InGaN quantum dots. Polarisation resolved spectroscopy of non-polar InGaN quantum dots reveals 100% linearly polarised emission for many quantum dots. For quantum dot emissions with a polarisation degree less than unity, a fine structure splitting between two orthogonal polarisation axes can be resolved in an optical setup with a simple top-down excitation geometry. A statistical investigation into the origins of spectral diffusion in polar InGaN quantum dots is presented, and spectral diffusion is attributed to charge carriers trapped at threading dislocations, and itinerant and trapped carriers in the underlying quantum well layer which forms during the growth procedure. Incorporating quantum dots into the intrinsic region of a p-i-n diode structure and applying a reverse bias is suggested as a method to reduce spectral diffusion. Coherent control of the excited state exciton in a non-polar InGaN quantum dot is experimentally demonstrated by observation of Rabi rotation between the excited state exciton and the crystal ground state. The exciton ground state photoluminescence is used as an indirect measurement of the excited state population.
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Wu, Zhengwei. "Quantum Corrections for Fundamental Plasma Behaviors." Thesis, The University of Sydney, 2009. https://hdl.handle.net/2123/29229.
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Quantum plasmas have received considerable attention in recent years. The
quantum effects become important if the typical distance separating particles in a
plasma system becomes comparable or less than the de Broglie wavelength of the
particles. This condition will be satisfied when the Fermi temperature is greater than
thermal temperature of plasmas; thus quantum effects become important. The electrons
in the plasmas approach to a Fermi gas, their statistical behavior is described
by Fermi—Dirac distribution instead of classical Boltzman distribution.
Quantum hydrodynamics (QHD) is the most widely used hydrodynamic model,
which deals with transport processes of particles, the momentum of particle and
macroscopic physical quantities like energy. Together with the status equation,
they form a complete set of equations to describe quantum plasmas from the fluid
dynamics’ point of View. Besides, Quantum Magnetohydrodynamic (QMHD) model
is established based on QHD equations and takes into account of magnetic field.
This research is based on QMHD model to investigate the different waves and fluid
instabilities in magnetized plasmas.
This thesis includes some parts as described in the following. First, based on the
quantum hydrodynamic equations with magnetic field, we investigated the disper—
sion relation of some types of linear waves in quantum magnetized plasmas. Our
results indicate that the quantum corrections have significant effects on the disper—
sion properties of the Langmuir wave.
Second, we studied the general dispersion equation for quantum magnetized
warm plasmas. Using the plasma dielectric tensor, we obtained the dispersion rela—
tions of magnetoelectric waves and multi-stream instability by solving the dispersion
equation. The parallel magnetic field has no effects on stream instability, while two—
stream instability is altered remarkably by quantum effects and thermal effects.
Third, the electromagnetic drift waves of nonuniform quantum magnetized EPI
plasmas on the basis of the QMHD model were discussed by taking the thermal and
Fermi pressure terms into account. We found that the drift wave is unstable when
the wave vector has a component along the axis and the growth rate is approximately
proportional to the square of the electron number density gradient.
Fourth, the electrostatic drift waves (EDWs) in nonuniform quantum pair plas—
mas placed in an external magnetic field were investigated. We derived the analytic
expression of the dispersion relation of EDWs with the presence of equilibrium mag—
netic field inhomogeneity and show that a new, purely quantum, branch appears.
This new electrostatic drift mode does not exist in classical pair plasmas and has
no vital relation with quantum statistic effects.
Next, the Rayleigh-Taylor (RT) instability in an ideal incompressible quantum
magnetized plasma system was researched. Using the exponential density distribu—
tion and fixed boundary conditions, we derive the analytical expression of the growth
rate of RT instability. The RT instability is affected significantly by quantum effects.
Quantum mechanical effects suppress the RT instability in proper circumstances.
Moreover, we calculated the electrostatic drift waves (EDW) in nonuniform three—
dimensional Fermi plasma placed in an external magnetic field. The dispersion
relation of EDW is obtained. The new quantum diamagnetic drift velocity and
quantum ion—acoustic velocity are introduced and shown to be much greater than
their respective value under classical circumstances, The dispersion relationship is
affected and altered obviously by quantum mechanical effects.
At the last, we consider the possible electrostatic drift waves (EDWs) in quantum
dusty plasmas. The dust self—gravitational effects are taken into account. One
can see that the Jeans terms induced by the dust gravitation perturbation exert
significant effects on the dispersion relation. Under these environment, a drift—like
instability is induced by the Jeans terms.
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Raji, Rufai Odutayo. "Nonlinear low frequency wave phenomena in space plasmas." Thesis, University of the Western Cape, 2013. http://hdl.handle.net/11394/4036.
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Philosophiae Doctor - PhD<br>In this thesis, using multispecies fluid plasma models, nonlinear electrostatic solitary wave fluctuations will be investigated in magnetized plasmas. The different models used for the investigation will be guided by the satellite observations in different regions of the Earth magnetosphere. These investigations will enable us to attempt theoretical explanations for the nonlinear potential structures observed in the satellite data. Multispecies plasma consisting of cool and hot electrons with Maxwellian distributions and fluid ions will be considered to study low frequency solitons. The ions will be considered as magnetized. The study will be extended to include magnetized oxygen ions. The model will be modified for regions of the magnetosphere consisting of two ions having Maxwellian distributions and magnetized electrons. The nonthermal distributions of energetic hot electrons and the Maxwellian distributions of cool electrons with magnetized cold ions fluid will also be considered. For all the models, the effect of ion and electron densities, temperatures, magnetic field strength and propagation angle will be studied during the investigation of soliton structures. In all the above mentioned studies, arbitrary amplitude theory is carried out by the Sagdeev pseudo-potential method. Further investigations on the charateristics and existence domains of the solitons is found both analytically and numerically, using satellite data where applicable
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Jenkins, Stewart David. "Theory of light -atomic ensemble interactions entanglement, storage, and retrieval /." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-09252006-175848/.
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Thesis (Ph. D.)--Physics, Georgia Institute of Technology, 2007.<br>Kennedy, T. A. Brian, Committee Chair ; Kuzmich, Alex, Committee Member ; Chapman, Michael S., Committee Member ; Raman, Chandra, Committee Member ; Morley, Thomas D., Committee Member.
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Hoffmann, Norah M. [Verfasser], and Ludwig [Akademischer Betreuer] Mathey. "Mixed Quantum-Classical Dynamics in Cavity Quantum Electrodynamics / Norah M. Hoffmann ; Betreuer: Ludwig Mathey." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2020. http://d-nb.info/1218707240/34.
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Waugh, Robert George. "Measurement of event shape variables in deep inelastic scattering." Thesis, University of Glasgow, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301504.
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Greiner, Christoph M. "Accelerated superradiance and pulse area quantization in atom-cavity systems /." view abstract or download file of text, 2002. http://wwwlib.umi.com/cr/uoregon/fullcit?p3045087.
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Thesis (Ph. D.)--University of Oregon, 2002.<br>Typescript. Includes vita and abstract. Includes bibliographical references (leaves 171-178). Also available for download via the World Wide Web; free to University of Oregon users.
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Dumur, Etienne. "A V-shape superconducting artificial atom for circuit quantum electrodynamics." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GRENY003/document.
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Cette thèse porte sur la réalisation expérimental d'un atome artificiel possédant un diagramme énergétique en forme de V. Inspiré par les expériences des ions piégés, nous avons théoriquement prédit une lecture ultra rapide et de haute fidélité de l'état d'un qubit en utilisant un atome artificiel en forme de V dans une architectures d'électrodynamiques de circuits quantique. Pour réaliser cette expérience, nous avons développé une installation expérimental pour effectuer des mesures de transmissions de nos circuits quantiques supra-conducteur par une méthode hétérodyne. Nous avons aussi mis en oeuvre un environnement matériel et logiciel permettant des spectroscopies multi-tons et des mesures résolus en temps afin de contrôler l'état quantique de l'atome artificiel et l'état de photon cohérent dans le résonateur. De plus nous avons caractérisé des résonateurs micro-ondes quart d'ondes fabriqués à partir d'Aluminium et de Rhénium épitaxié. Le dispositif quantique original est fabriqué en couplant inductivement deux transmons. Lorsque le couplage inductif est de l'ordre de grandeur de l'inductance Josephson, nous observons des modes d'oscillations "en-phase" et "hors-phase" de la phase à travers les jonctions. Le spectre d'énergie du système, mesuré par des spectroscopies deux-tons, est précisément décrit par notre modèle analytique. Dans la limite des excitations de petites énergies, les deux modes peuvent être considérés comme des simples systèmes à deux niveaux appelés ci-après qubits. A zéro champ magnétique, il a été observé que les deux qubits deviennent couplés uniquement par une anharmonicité croisée. Cela a été révélé, à travers des spectroscopies trois-tons, par un décalage conditionnel de la fréquence de transition d'un qubit dépendant de l'état de l'autre qubit aussi grand que 115 MHz. Tous ces résultats expérimentaux démontrent un diagramme énergétique en V pour notre atome artificiel ce qui ouvre la voie pour des expérience originales dans le domaine de l'électrodynamique quantique<br>This thesis focuses on the experimental realisation of an artificial atom with a V-shape energy level diagram.Inspired by trapped-ion experiments, we theoretically predict an ultra fast and high fidelity quantum nondestructive readout of qubit state by using the V-shape artificial atom in a circuit quantum electrodynamicsarchitecture.To realise this experiment, we have developed an experimental setup to perform transmission measurementsof our superconducting quantum circuits by heterodyne technique at very low temperatures (30mK) and verylow signal amplitude (fW). We also implemented a hardware and software environment enabling multi-tonespectroscopies and time-resolved measurements in order to control the quantum state of the artificial atomand the coherent field in the resonator. In addition, in order to optimise the experiment circuits we havecharacterised quarterwave microwave resonators made from aluminium and epitaxial rhenium thin films.The original quantum device is fabricated by two inductively coupled transmons. When the couplinginductance is of the order of the Josephson inductance, we observe “in-phase” and “out-of-phase” oscillatingmodes of the superconducting phase across the junctions. The energy spectrum of the system, measured bytwo-tone spectroscopy, is magnetic flux dependent. It is precisely described by our theoretical model leadingto an accurate determination of the circuit parameters. Because of their anharmonicity, in the low-energylimit, the two modes can be considered as two-level systems called qubits. At zero magnetic field, it hasbeen observed that the two qubits become coupled only by a cross-anharmonicity. This has been revealed,through three-tone spectroscopy, by a conditional frequency shift as large as 115MHz of one qubit transitiondepending on the other qubit state. All these experimental results demonstrate a V-shape energy diagram forour artificial atom which paves the way to an original and high performance read-out
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Howie, David John Henry. "Measurement of 1s2s '3Sâ†1-1s2p '3Pâ†2â†,â†0 transitions in heliumlike silicon, phosphorus, and sulphur." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239310.
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McClelland, Anthony Francis. "Development of a novel technique for the measurement of the 1sâ†1â†/â†2 Lamb shift in high Z hydrogenic ions by Lyman #alpha#/Balmer #beta# wavelength intercomparison." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314909.
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Chantler, Christopher Thomas. "Beam-foil spectroscopy of highly-ionized atoms, precision measurements of hydrogenic Lamb shifts and x-ray diffraction of curved crystals." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276810.
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Balkwill, C. "A study of the reactions e'+e'- #-># #mu#'+ #mu#'- and e'+e'- #-># #tau#'+ #tau#'- at centre of mass energies between 35 and 47 GeV." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233471.
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Quiney, H. M. "Finite basis set studies of the Dirac equation." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379934.
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