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1
De, Santis Lorenzo. "Single photon generation and manipulation with semiconductor quantum dot devices." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS034/document.
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Les phénomènes quantiques les plus fondamentaux comme la cohérence quantique et l’intrication sont aujourd'hui explorés pour réaliser de nouvelles technologies. C'est le domaine des technologies quantiques, qui promettent de révolutionner le calcul, la communication et la métrologie. En encodant l'information dans les systèmes quantiques, il serait possible de résoudre des problèmes inaccessibles aux ordinateurs classiques, de garantir une sécurité absolue dans les communications et de développer des capteurs dépassant les limites classiques de précision. Les photons uniques, en tant que vecteurs d'information quantique, ont acquis un rôle central dans ce domaine, car ils peuvent être manipulés facilement et être utilisés pour mettre en œuvre de nombreux protocoles quantiques. Pour cela, il est essentiel de développer des interfaces très efficaces entre les photons et les systèmes quantiques matériels, tels les atomes uniques, une fonctionnalité fondamentale à la fois pour la génération et la manipulation des photons. La réalisation de tels systèmes dans l'état solide permettrait de fabriquer des dispositifs quantiques intégrés et à large échelle. Dans ce travail de thèse, nous étudions l'interface lumière-matière réalisée par une boîte quantique unique, utilisée comme un atome artificiel, couplée de façon déterministe à une cavité de type micropilier. Un tel dispositif s'avère être un émetteur et un récepteur efficace de photons uniques, et il est utilisé ici pour implémenter des fonctionnalités quantiques de base. Tout d'abord, sous une excitation optique résonante, nous montrons comment nos composants sont des sources très brillantes de photons uniques. L’accélération de l'émission spontanée de la boîte quantique dans la cavité et le contrôle électrique de la structure permettent de générer des photons très indiscernables avec une très haute brillance. Cette nouvelle génération de sources de photons uniques peut être utilisée pour générer des états de photons intriqués en chemin appelés états NOON. Ces états intriqués sont des ressources importantes pour la détection de phase optique, mais leur caractérisation optique a été peu étudiée jusqu’à présent. Nous présentons une nouvelle méthode de tomographie pour caractériser les états de NOON encodés en chemin et implémentons expérimentalement cette méthode dans le cas de deux photons. Enfin, nous étudions le comportement de nos composants comme filtres non-linéaires de lumière. L'interface optimale entre la lumière et la boîte quantique permet l'observation d'une réponse optique non-linéaire au niveau d'un seul photon incident. Cet effet est utilisé pour démontrer le filtrage des états Fock à un seul photon à partir d’impulsions classiques incidentes. Ceci ouvre la voie à la réalisation efficace d’interactions effectives entre deux photons dans un système à l’état solide, une étape fondamentale pour surmonter les limitations dues au fonctionnement probabilistes des portes optiques linéairesQuantum phenomena can nowadays be engineered to realize fundamentally new applications. This is the field of quantum technology, which holds the promise of revolutionizing computation, communication and metrology. By encoding the information in quantum mechanical systems, it appears to be possible to solve classically intractable problems, achieve absolute security in distant communications and beat the classical limits for precision measurements. Single photons as quantum information carriers play a central role in this field, as they can be easily manipulated and can be used to implement many quantum protocols. A key aspect is the interfacing between photons and matter quantum systems, a fundamental operation both for the generation and the readout of the photons. This has been driving a lot of research toward the realization of efficient atom-cavity systems, which allows the deterministic and reversible transfer of the information between the flying photons and the optical transition of a stationary atom. The realization of such systems in the solid-state gives the possibility of fabricating integrated and scalable quantum devices. With this objective, in this thesis work, we study the light-matter interface provided by a single semiconductor quantum dot, acting as an artificial atom, deterministically coupled to a micropillar cavity. Such a device is shown to be an efficient emitter and receiver of single photons, and is used to implement basic quantum functionalities.First, under resonant optical excitation, the device is shown to act as a very bright source of single photons. The strong acceleration of the spontaneous emission in the cavity and the electrical control of the structure, allow generating highly indistinguishable photons with a record brightness. This new generation of single photon sources can be used to generate path entangled NOON states. Such entangled states are important resources for sensing application, but their full characterizatiob has been scarcely studied. We propose here a novel tomography method to fully characterize path entangled N00N state and experimentally demonstrate the method to derive the density matrix of a two-photon path entangled state. Finally, we study the effect of the quantum dot-cavity device as a non-linear filter. The optimal light matter interface achieved here leads to the observation of an optical nonlinear response at the level of a single incident photon. This effect is used to demonstrate the filtering of single photon Fock state from classical incident light pulses. This opens the way towards the realization of efficient photon-photon effective interactions in the solid state, a fundamental step to overcome the limitations arising from the probabilistic operations of linear optical gates that are currently employed in quantum computation and communication
2
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 QEDCette 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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Srivastava, Vineesha. "Entanglement generation and quantum gates with quantum emitters in a cavity." Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAF069.
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Cette thèse présente de nouveaux protocoles pour les portes quantiques multi-qubits non locales et la génération d’intrication dans des systèmes où plusieurs émetteurs quantiques interagissent avec un mode bosonique partagé. Elle introduit les portes de phase géométrique et adiabatique, avec des expressions analytiques de l’infidélité dépendant du nombre de qubits et de la coopérativité. Pour deux qubits, elles forment un ensemble universel, tandis que dans les systèmes multi-qubits, elles permettent des portes déterministes pour la simulation quantique et la correction d’erreurs. Une contribution majeure est un protocole de détection optimisé par l’intrication, atteignant une haute précision de mesure grâce au contrôle optimal. La thèse explore aussi un mécanisme de blocage polaritonique en cavité pour la génération d’états W non locaux et de portes multi-qubits. Ces opérations déterministes, basées sur des excitations classiques de cavité et parfois des impulsions globales, offrent une base évolutive pour l’informatique quantique, la détection quantique et l'internet quantique de demain, en particulier pour les systèmes à atomes neutresThis thesis presents novel protocols for non-local multi-qubit quantum gates and entanglement generation in systems where multiple quantum emitters interact with a shared bosonic mode. It introduces the Geometric and Adiabatic Phase Gates, with closed-form infidelity expressions scaling with qubit number and cooperativity. For two qubits, these form a universal gate set, while in multi-qubit systems, they enable deterministic gates for quantum simulation and quantum error correction. A key contribution is an entanglement-enhanced sensing protocol that achieves high measurement precision via optimal control. The thesis also examines a cavity polariton blockade mechanism for non-local W-state generation and multi-qubit gates. These deterministic multi-qubit operations rely only on classical cavity drives and, in some cases, global qubit pulses, providing a scalable foundation for quantum computing, sensing, and the future quantum internet, especially for neutral atom systems
4
Diniz, Igor. "Electrodynamique quantique des les atomes artificiels supraconducteurs." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00771451.
Full textAbstract:
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.
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Martini, Ullrich. "Cavity QED with many atoms." Diss., [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=963141449.
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Boozer, Allen David Kimble H. Jeff. "Raman transitions in cavity QED /." Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-05272005-160246.
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Birnbaum, Kevin Michael Kimble H. Jeff. "Cavity QED with multilevel atoms /." Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-05272005-103306.
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Northup, Tracy Eleanor Kimble H. Jeff Kimble H. Jeff. "Coherent control in cavity QED /." Diss., Pasadena, Calif. : California Institute of Technology, 2008. http://resolver.caltech.edu/CaltechETD:etd-05242008-114227.
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Brama, Elisabeth. "Ion trap cavity system for strongly coupled cavity-QED." Thesis, University of Sussex, 2013. http://sro.sussex.ac.uk/id/eprint/45218/.
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The combination of an ion trap with a high finesse optical cavity is an ideal system for the investigation of strong coupling cavity quantum electrodynamics, and allows the observation of a number of interesting quantum phenomena. To achieve the small mode volumes required without impairing the ion trapping small traps with a short ion electrode distance are needed. Two microscopic linear rf ion traps have been developed and built to accommodate experimental cavities of lengths of several 100 microns. The first trap design, the 'sandwich' trap, was successfully used to trap 40Ca+ - ions for several hours. It was characterised extensively including a measurement of the heating rates of the ions in the trap. Spectroscopy measurements of the cooling transition, as well as the two repumping transitions were carried out. The second trap design, the 'alumina' trap, also successfully trapped 40Ca+ - ions, and a full characterisation of this trap was made. The experimental cavity was installed at a preliminary cavity length distance of 3.7 mm. The cavity characteristics were examined. Finally the trapped ions were overlapped with the cavity mode by adjusting the trap minimum position along the trap axis via dc voltages and the vertical position of the cavity. To progress further a locking scheme for the cavity length as well as a single - photon detection setup are necessary. To achieve strong coupling a reduction of the cavity length will have to be made.
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Alqahtani, Moteb M. "Multi-photon processes in cavity QED." Thesis, University of Sussex, 2014. http://sro.sussex.ac.uk/id/eprint/49632/.
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Based on a multi-mode multi-level Jaynes-Cummings model and multi-photon resonance theory, a set of universal two-qubit and three-qubit gates has been realized where dual-rail qubits are encoded in cavities. In this way, the information has been stored in cavities and the off-resonant levels have been eliminated by the theory of an effective two-level Hamiltonian. A further model, namely the spin-J model, has been introduced so that a complete population inversion for levels of interest has been achieved and periodic multilevel multi-photon models have been performed. The combination of the two models has been employed to address two-level, three-level, four-level, and even five-level configurations. Considering the present cavity-QED experiments, several numerical simulations have been designed in order to check the robustness of the logic gates to variations in experimentally important parameters including the coupling constants and the detunings. Finally, based on Liouville's equation, and the wave-function treatments, the impact of decoherence processes on the fidelity of the qubit states in the iSWAP and the Fredkin gates has been studied. This thesis may have applications to quantum information processing, involving logic with simple quantum bits, with the possible application to the building of a quantum computer.
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Armen, Michael A. Mabuchi Hideo Mabuchi Hideo. "Bifurcations in single atom cavity QED /." Diss., Pasadena, Calif. : California Institute of Technology, 2009. http://resolver.caltech.edu/CaltechETD:etd-05262009-100436.
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Terraciano, Matthew Louis. "Cross-correlations and entanglement in cavity QED." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3767.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis 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.
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Larson, Jonas. "Extended Jaynes-Cummings Models In Cavity Qed." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-404.
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Baldwin, Charles H. "Cavity QED with Center of Mass Tunneling." Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1312237577.
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Kim, Soo Y. "Cold single atoms for cavity QED experiments." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26581.
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Thesis (Ph.D)--Physics, Georgia Institute of Technology, 2009.Committee Chair: Chapman, Michael; Committee Member: Citrin, David; Committee Member: Kennedy, T. A. Brian; Committee Member: Kuzmich, Alexander; Committee Member: Raman, Chandra. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Connolly, Elizabeth Wilcut Kimble H. Jeff Kimble H. Jeff. "Experiments with toroidal microresonators in cavity QED /." Diss., Pasadena, Calif. : California Institute of Technology, 2009. http://resolver.caltech.edu/CaltechETD:etd-05282009-101209.
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Dotsenko, Igor. "Single atoms on demand for cavity QED experiments." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=984484124.
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Seymour-Smith, Nicolas R. "Ion-trap cavity QED system for probabilistic entanglement." Thesis, University of Sussex, 2012. http://sro.sussex.ac.uk/id/eprint/39687/.
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Laser systems and a linear radiofrequency (rf) Paul trap with an integrated co-axial cavity have been developed for experiments in cavity QED and probabilistic entanglement. Single 40Ca+ ions and large Coulomb crystals have been trapped routinely and laser cooled with long trapping lifetimes. A technique to achieve precise overlap of the pseudopotential minimum of the rf-field with the cavity mode has been implemented through variable capacitors in the resonant rf-circuit used to drive the trap. Three-dimensional micromotion compensation has been implemented. An 894 nm laser has been frequency stabilised to a Pound-Drever-Hall cavity which is in turn stabilised to atomic Cs using polarisation spectroscopy. The Allan variance of the error signal has been reduced to less than a kilohertz on timescales greater than a second. A novel implementation of the scanning cavity transfer lock has been developed to transfer the stability of the 894 nm laser to the 397 nm ion cooling and 866 nm repumping lasers. The bandwidth of the system has been increased to 380 Hz and the Allan variance of the error signal has been reduced to less than ten kilohertz on timescales of greater than a second. The pseudopotential minimum of the rf field has been overlapped optimally with the optical cavity mode through mapping of the fluorescence from cavity-field repumped ions as a function of their displacement. Coupling to the cavity mode has been confirmed by observation of resonant fluorescence into the cavity mode using the cavity-assisted Raman transition process. The thesis demonstrates that the setup is ready for the controlled production of single photons with pre-determined polarisation states, and progression onto new schemes to entangle multiple ions that are coupled to the optical cavity mode.
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Everitt, Mark Stanley. "Construction, theory and simulation of cavity QED systems." Thesis, University of Leeds, 2009. http://etheses.whiterose.ac.uk/2786/.
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The microscopically pumped maser, or micromaser is a cavity QED experiment intended to be a physical realisation of the Jaynes-Cummings model of a single two-level atom interacting with a single mode electromagnetic field. This is the simplest model that describes the interaction between light and matter, yet it predicts behaviour unexpected from semiclassical models, such as the revival of Rabi oscillations of an atom interacting with an initially coherent field and non-monotonic linewidth as a function of pumping. The micromaser at the University of Leeds consists of a high quality superconducting microwave cavity designed to be resonant with the transition between two specific Rydberg states of rubidium. These two states behave like an ideal two level atom, and couple strongly to the cavity field due to a large dipole moment. These Rydberg atoms are passed through the cavity in a rarified beam such that in most instances when there is an atom in the cavity, there will only be one, closely approximating the Jaynes-Cummings model. I present experimental work on the build phase of the micromaser. Specifically I routed all of the wiring and microwave lines in the cryostat that contains the micromaser, and designed mounts for various components. I also designed several testing methods for probing high quality microwave cavity resonances and quality factors which are presented. Using the Jaynes-Cummings model as a prototype, I demonstrate how extensions to the model can be used to construct universal quantum logic gates that operate on photonic qubits in a multi-mode cavity. This could be realised in a micromaser with a multi-mode cavity. Conversely, I demonstrate that by using atoms as qubits, detuned cavities can be used to generate entangled resources such as the Greenberger-Horne-Zeilinger state, the W state, and graph states of atoms. I show that single qubit rotations on Rydberg atom qubits have already been experimentally demonstrated so that in combination these entangled resources are useful for quantum metrology, quantum computation and even tests of quantum gravity.
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Hannigan, Justin Michio 1977. "Hemispherical optical microcavity for cavity-QED strong coupling." Thesis, University of Oregon, 2009. http://hdl.handle.net/1794/10548.
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xv, 204 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.This thesis reports on progress made toward realizing strong cavity quantum electrodynamics coupling in a novel micro-cavity operating close to the hemispherical limit. Micro-cavities are ubiquitous wherever the aim is observing strong interactions in the low-energy limit. The cavity used in this work boasts a novel combination of properties. It utilizes a curved mirror with radius in the range of 40-60 µm that exhibits high reflectivity over a large solid angle and is capable of producing a diffraction limited mode waist in the approach to the hemispherical limit. This small waist implies a correspondingly small effective mode volume due to concentration of the field into a small transverse distance. The cavity assembled for this investigation possesses suitably low loss (suitably low linewidth) to observe vacuum Rabi splitting under suitable conditions. According to best estimates for the relevant system parameters, this system should be capable of displaying strong coupling. The dipole coupling strength, cavity loss and quantum dot dephasing rates are estimated to be, respectively, g = 35µeV, κ = 30µeV, and γ = 15µeV. A survey of two different distributed Bragg reflector (DBR) samples was carried out. Four different probe lasers were used to measure transmission spectra for the coupled cavity-QED system. The system initially failed to display strong coupling due to the available lasers being too far from the design wavelength of the spacer layer, corresponding to a loss of field strength at the location of the quantum dots. Unfortunately, the only available lasers capable of probing the design wavelength of the spacer layer had technical problems that prevented us from obtaining clean spectra. Both a Ti:Al 2 O 3 and a diode laser were used to measure transmission over the design wavelength range. The cavity used here has many promising features and should be capable of displaying strong coupling. It is believed that with a laser system centered at the design wavelength and possessing low enough linewidth and single-mode operation across a wide wavelength range strong coupling should be observable in this system.
Committee in charge: Hailin Wang, Chairperson, Physics; Michael Raymer, Advisor, Physics; Jens Noeckel, Member, Physics; Richard Taylor, Member, Physics; Andrew Marcus, Outside Member, Chemistry
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Fortier, Kevin Michael. "Individual Trapped Atoms for Cavity QED Quantum Information Applications." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14625.
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To utilize a single atom as a quantum bit for a quantum computer requires exquisite
control over the internal and external degrees of freedom. This thesis develops techniques
for controlling the external degrees of freedom of individual atoms. In the first part of
this thesis, individual atoms are trapped and detected non-destructively by the addition of
cooling beams in an optical lattice. This non-destructive imaging technique led to atomic
storage times of two minutes in an optical lattice. The second part of thesis incorporated
the individual atoms into a high finesse cavity. Inside this optical cavity, atoms are cooled
and non-destructively observed for up to 10 seconds.
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Thoumany, Pierre. "Optical Spectroscopy and Cavity QED Experiments with Rydberg Atoms." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-130845.
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Lynn, Theresa W. Kimble H. Jeff. "Measurement and control of individual quanta in cavity QED /." Diss., Pasadena, Calif. : California Institute of Technology, 2003. http://resolver.caltech.edu/CaltechETD:etd-04082003-111058.
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Akram, Uzma. "Quantum interference and cavity QED effects in a V-system /." [St. Lucia, Qld.], 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17140.pdf.
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Al-Amri, Mohammad D. "Cavity QED and atom optics in planar dielectric/metallic structures." Thesis, University of York, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421498.
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Skipsey, Samuel Cadellin. "Cavity QED and correlation effects in sharply intersecting conducting structures." Thesis, University of York, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442373.
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Li, Benliang. "Cavity QED of superradiant phase transition in two dimensional materials." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/427724/.
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In modern physics, the investigation of the interaction between light and matter is important from both a fundamental and an applied point of view. Cavity quantum electrodynamics (cavity QED) is the study of the interaction between light confined in a reflective cavity and atoms or other particles where the quantum nature of light photons is significant. The strong interaction between an exciton and cavity photon in a high-finesse microcavity can induce a hybrid light-matter eigenstate which is usually named as polariton in solid-state systems. This strong light-matter interaction can be achieved when this interaction is larger than all broadenings caused by other various factors e.g. electron phonon scattering and cavity loss. The polariton is now stimulating tremendous research interests due to its high potential in cavity quantum electrodynamics (QED) and the achievement of polaritonic devices. Moreover, when the interaction strength between an excitation and the cavity photon, quantified by vacuum Rabi frequency, becomes comparable to or larger than the corresponding electronic transition frequency in a cavity, the system can enter an ultrastrong coupling regime, which has been experimentally observed. In this regime, the standard rotating-wave approximation is no longer valid and the antiresonant term of the interaction Hamiltonian starts to play an important role, giving rise to exciting effects in cavity QED. The Aharonov-Bohm (AB) effect is a fundamental quantum phenomenon that bears the significance of the nature of electromagnetic fields and potentials. Besides its fundamental significance in quantum theory, its importance for applications in interferometric devices is omnipresent. Recently, since the 2D materials have triggered immense interest, some work has been done to integrate the AB effect with the electronic and transport properties of 2D materials. This thesis consists of two parts. In the first part, the light-matter coupling between cyclotron transition and photon is theoretically investigated in some 2-D materials such as the monolayer MoS2, graphene and monolayer black phosphorene (BP) systems. The results show that, in these 2-D materials, the ultrastrong light-matter coupling can be achieved at a high filling factor of Landau levels. Furthermore, we show that, in contrast to the case for conventional semiconductor resonators, the MoS2 system shows a vacuum instability. In monolayer MoS2 resonator, the diamagnetic term can still play an important role in determining magnetopolariton dispersion which is different from monolayer graphene system. The diamagnetic term arises from electron-hole asymmetry which indicates that electron-hole asymmetry can influence the quantum phase transition. Meanwhile, we show that, similar with some other 2D materials such as graphene and MoS2, the monolayer BP system shows a vacuum instability. However, in contrast with other 2D materials, the BP system displays a large energy gap between three branches of polaritons because of its strong anisotropic behavior in the eigenstates of the band structures. For the graphene system, we investigate the coupling of cyclotron transition and a multimode cavity described by a multimode Dicke model. This model exhibits a superradiant quantum phase transition, which we describe exactly in an effective Hamiltonian approach. The complete excitation spectrum in both the normal phase and superradiant phase regimes is given. At last, in contrast to the single mode case, multimode coupling of cavity photon and cyclotron transition can greatly reduce the critical vacuum Rabi frequency required for quantum phase transition, and dramatically enhance the superradiant emission by fast modulating the Hamiltonian. Our study provides new insights in cavity-controlled magneto-transport in these 2-D systems, which could lead to the development of polariton-based devices. The second part is a diversion from the main content of this thesis; readers who are not interested in foundational issues of physics can skip this part. For one charged quantum particle P moving in an electromagnetic vector potential Aˆµ = ( φˆ, - Aˆ ) created by some other charged particles, we can either use the framework of one particle quantum mechanics (OPQM) to calculate the evolutions of P, or we can treat this as an multi-particles problem in the framework of quantum field theory and calculate the evolution of P. These two methods need to be equivalent, i.e., they produce the same result for the evolution of P. One open question is how to describe the evolution of P within the framework of quantum field theory and show that these two methods yield the same result? In chapter 5, we are going to derive the OPQM from the quantum field theory, i.e., the quantum electrodynamics (QED) to be specific. We start with the discussions on the AB effect then raise a plausible interpretation within the QED framework. We provide a quantum treatment of the source of the electromagnetic potential and argue that the underlying mechanism in AB effect can be viewed as interactions between electrons described by QED theory where the interactions are mediated by virtual photons. On further analysis, we show that the framework of one particle quantum mechanics (OPQM) can be given, in general, as a mathematically approximated model which is reformulated from QED theory while the AB effect scheme provides a platform for our derivations. In addition, the classical Maxwell equations are derived from QED scattering process while both classical electromagnetic fields and potentials serve as mathematical tools that are constructed to approximate the interactions among elementary particles described by QED physics. This work opens up a new perspective on the nature of electromagnetic fields and potentials.
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Jones, Dyan Lynne. "Quantum Fluctuations of a Cavity QED System with Periodic Potential." Miami University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=miami1121696082.
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Steele, Adam V. "Barium ion cavity qed and triply ionized thorium ion trapping." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26530.
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Thesis (Ph.D)--Physics, Georgia Institute of Technology, 2009.Committee Chair: Michael Chapman; Committee Member: Alex Kuzmich; Committee Member: Brian Kennedy; Committee Member: Chandra Raman; Committee Member: Kenneth Brown. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Richards, Benjamin Colby. "1D and 2D Photonic Crystal Nanocavities for Semiconductor Cavity QED." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/145275.
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The topic of this dissertation is photonic crystal nanocavities for semiconductor cavity quantum electrodynamics. For the purposes of this study, these nanocavities may be one dimensional (1D) or two dimensional (2D) in design. The 2D devices are active and contain embedded InAs quantum dots (QDs), whereas the 1D devices are passive and contain no active emitters. The 2D photonic crystal nanocavities are fabricated in a slab of GaAs with a single layer of InAs QDs embedded in the slab. When a cavity mode substantially overlaps the QD ensemble, the dots affect the linewidths of the observed modes, leading to broadening of the linewidth at low excitation powers due to absorption and narrowing of the linewidths at high excitation powers due to gain when the QD ensemble absorption is saturated. We observe lasing from a few QDs in such a nanocavity. A technique is discussed with allows us to tune the resonance wavelength of a nanocavity by condensation of an inert gas onto the sample, which is held at cryogenic temperatures. The structural quality at the interfaces of epitaxially grown semiconductor heterostructures is investigated, and a growth instability is discovered which leads to roughness on the bottom of the GaAs slabs. Adjustment of MBE growth parameters leads to the elimination of this roughness, and the result is higher nanocavity quality factors. A number of methods for optimizing the fabrication of nanocavities is presented, which lead to higher quality factors. It is shown that some fundamental limiting factor, not yet fully understood, is preventing high quality factors at wavelengths shorter than 950 nm. Silicon 1D devices without active emitters are investigated by means of a tapered microfiber loop, and high quality factors are observed. This measurement technique is compared to a cross-polarized resonant scattering method. The quality factors observed in the silicon nanocavities are higher than those observed in GaAs, consistent with our observation that quality factors are in general higher at longer wavelengths.
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Haakh, Harald Richard. "Cavity QED with superconductors and its application to the Casimir effect." Master's thesis, Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2009/3256/.
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Diese Diplomarbeit untersucht den Casimir-Effekt zwischen normal- und supraleitenden Platten über einen weiten Temperaturbereich, sowie die Casimir-Polder-Wechselwirkung zwischen einem Atom und einer solchen Oberfläche. Hierzu wurden vorwiegend numerische und asymptotische Rechnungen durchgeführt. Die optischen Eigenschaften der Oberflächen werden dann aus dielektrischen Funktionen oder optischen Leitfähigkeiten erhalten.
Wichtige Modellen werden vorgestellt und insbesondere im Hinblick auf ihre analytischen und kausalen Eigenschaften untersucht.
Es wird vorgestellt, wie sich die Casimir-Energie zwischen zwei normalleitenden Platten berechnen lässt. Frühere Arbeiten über den in allen metallischen Kavitäten vorhandenen Beitrag von Oberflächenplasmonen zur Casimir-Wechselwirkung wurden zum ersten mal auf endliche Temperaturen erweitert. Für Supraleiter wird eine analytische Fortsetzung der BCS-Leitfähigkeiten zu rein imaginären Frequenzen, sowohl innerhalb wie außerhalb des schmutzigen Grenzfalles verschwindender mittlerer freier Weglänge vorgestellt. Es wird gezeigt, dass die aus dieser neuen Beschreibung erhaltene freie Casimir-Energie in bestimmten Bereichen der Materialparameter hervorragend mit der im Rahmen des Zwei-Fluid-Modells für den Supraleiter berechneten übereinstimmt. Die Casimir-Entropie einer supraleitenden Kavität erfüllt den Nernstschen Wärmesatz und weist einen charakteristischen Sprung beim Erreichen des supraleitenden Phasenübergangs auf. Diese Effekte treten ebenfalls in der magnetischen Casimir-Polder-Wechselwirkung eines Atoms mit einer supraleitenden Oberfläche auf.
Es wird ferner gezeigt, dass die magnetische Dipol-Wechselwirkung eines Atomes mit einem Metall sehr stark von den dissipativen Eigenschaften und insbesondere von den Oberflächenströmen abhängt. Dies führt zu einer starken Unterdrückung der magnetischen Casimir-Polder-Energie bei endlichen Temperaturen und Abständen oberhalb der thermischen Wellenlänge. Die Casimir-Polder-Entropie verletzt in einigen Modellen den Nernstschen Wärmesatz.Ähnliche Effekte werden für den Casimir-Effekt zwischen Platten kontrovers diskutiert. In den entsprechenden elektrischen Dipol-Wechselwirkungen tritt keiner dieser Effekte auf.
Die Ergebnisse dieser Arbeit legen nahe, das bekannte Plasma-Modells als Grenzfall eines Supraleiters bei niedrigen Temperaturen (bekannt als London-Theorie) zu betrachten, statt als Beschreibung eines normales Metalles.
Supraleiter bieten die Möglichkeit, die Dissipation der Oberflächenströme in hohem Maße zu steuern. Dies könnte einen experimentellen Zugang zu den optischen Eigenschaften von Metallen bei niedrigen Frequenzen erlauben, die eng mit dem thermischen Casimir-Effekt verknüpft sind. Anders als in entsprechenden Mikrowellen-Experimenten sind hierbei die Energien und Impulse unabhängige Größen. Die Messung der Oberflächenwechselwirkung zwischen Atomen und Supraleitern ist mit den heute verfügbaren Atomfallen auf Mikrochips möglich und der magnetische Anteil der Wechselwirkung sollte spektroskopischen Techniken zugänglich seinThis thesis investigates the Casimir effect between plates made of normal and superconducting metals over a broad range of temperatures, as well as the Casimir-Polder interaction of an atom to such a surface. Numerical and asymptotical calculations have been the main tools in order to do so. The optical properties of the surfaces are described by dielectric functions or optical conductivities, which are reviewed for common models and have been analyzed with special weight on distributional properties and causality. The calculation of the Casimir energy between two normally conducting plates (cavity) is reviewed and previous work on the contribution to the Casimir energy due to the surface plasmons, present in all metallic cavities, has been generalized to finite temperatures for the first time. In the field of superconductivity, a new analytical continuation of the BCS conductivity to to purely imaginary frequencies has been obtained both inside and outside the extremely dirty limit of vanishing mean free path. The Casimir free energy calculated from this description was shown to coincide well with the values obtained from the two fluid model of superconductivity in certain regimes of the material parameters. The Casimir entropy in a superconducting cavity fulfills the third law of thermodynamics and features a characteristic discontinuity at the phase transition temperature. These effects were equally encountered in the Casimir-Polder interaction of an atom with a superconducting wall. The magnetic dipole coupling of an atom to a metal was shown to be highly sensible to dissipation and especially to the surface currents. This leads to a strong quenching of the magnetic Casimir-Polder energy at finite temperature. Violations of the third law of thermodynamics are encountered in special models, similar to phenomena in the Casimir-effect between two plates, that are debated controversely. None of these effects occurs in the analog electric dipole interaction. The results of this work suggest to reestablish the well-known plasma model as the low temperature limit of a superconductor as in London theory rather than use it for the description of normal metals. Superconductors offer the opportunity to control the dissipation of surface currents to a great extent. This could be used to access experimentally the low frequency optical response of metals, which is strongly connected to the thermal Casimir-effect. Here, differently from corresponding microwave experiments, energy and momentum are independent quantities. A measurement of the total Casimir-Polder interaction of atoms with superconductors seems to be in reach in today’s microchip-based atom-traps and the contribution due to magnetic coupling might be accessed by spectroscopic techniques
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Lougovski, Pavel. "Quantum state engineering and reconstruction in cavity QED : an analytical approach." Diss., lmu, 2004. http://nbn-resolving.de/urn/resolver.pl?urn=urn:nbn:de:bvb:19-26381.
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Reinhard, Andreas [Verfasser]. "Strong Photon-Photon Interactions in Solid State Cavity QED / Andreas Reinhard." München : Verlag Dr. Hut, 2013. http://d-nb.info/1034003194/34.
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Fang-Yen, Christopher Minwah 1973. "Multiple thresholds and many-atom dynamics in the cavity QED microlaser." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8294.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2002.Includes bibliographical references (p. 263-270).
This thesis describes a study of a cavity QED microlaser in which many atoms are present simultaneously and atom-cavity interaction is well-defined. The microlaser is found to display multiple thresholds analogous to first-order phase transitions of the cavity field. Hysteresis is observed as a function of atom-cavity detuning and number of atoms. Data is compared with a rate equation model and fully quantized treatment based on micromaser theory. Good agreement between theory and experiment is found when the cavity is resonant with atoms of the most probable velocity, but long lifetimes of metastable states preclude the observation of true steady-state transition points. For nonzero atom-cavity detuning the microlaser displays broadenings and shifts which are not yet well-understood. Quantum trajectory simulations are performed to investigate many-atom and finite transit time effects in the microlaser. We show that over a wide range of parameters the many-atom microlaser scales with the single-atom theory, with a perturbation in the photon statistics due to cavity decay during the atom transit time.
by Christopher Minwah Fang-Yen.
Ph.D.
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McKeever, Jason Terence Taylor Kimble H. Jeff. "Trapped atoms in cavity QED for quantum optics and quantum information /." Diss., Pasadena, Calif. : California Institute of Technology, 2004. http://resolver.caltech.edu/CaltechETD:etd-06032004-163753.
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Fan, Xudong. "Cavity-QED studies of composite semiconductor nanostructure and dielectric microsphere systems /." view abstract or download file of text, 2000. http://wwwlib.umi.com/cr/uoregon/fullcit?p9998030.
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Thesis (Ph. D.)--University of Oregon, 2000.Includes reprints of articles previously published by the author. Typescript. Includes vita and abstract. Includes bibliographical references (leaves 184-190). Also available for download via the World Wide Web; free to University of Oregon users.
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Bakemeier, Lutz [Verfasser]. "Quantum to classical crossover in cavity QED and optomechanical systems / Lutz Bakemeier." Greifswald : Universitätsbibliothek Greifswald, 2014. http://d-nb.info/1062630971/34.
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Constantinos, Lazarou. "Adiabatic processes in cavit QED and the coherent control of trapped ions." Thesis, University of Sussex, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504323.
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Tischler, Jonathan Randall 1977. "Solid state cavity QED : practical applications of strong coupling of light and matter." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40549.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 126-133).
J-aggregates of cyanine dyes are the excitonic materials of choice for realizing polariton devices that operate in strong coupling at room temperature. Since the earliest days of cavity QED, there has been a major desire to construct solid state optical devices that operate in the limit where strong light-matter interactions dominate the dynamics. Such devices have been successfully constructed, but their operation is usually limited to cryogenic temperatures, because of the small binding energies for the ,excitonic materials typically used. It has been demonstrated that when J-aggregates are used as the excitonic material, it is possible to achieve strong coupling in solid state even at room temperature. J-aggregates are a unique choice of materials because their central feature, a very large optical transitional dipole, is itself the result of strong coupling amongst monomeric dye elements. The strong coupling amongst dye molecules produces a well-defined cooperative optical transition possessing oscillator strength derived from all of the aggregated monomers that is capable of interacting strongly with the cavity confined electromagnetic field even at room temperature. There are different materials and methods for assembling J-aggregates which are capable of producing strong coupling. This thesis argues in favor of a particular dye and method of assembly which are then thoroughly characterized. With this dye and assembly technique, the first demonstration of electrically pumped polariton emission is reported as is the largest optical absorption coefficient for a solid thin film at room temperature not contained in a full microcavity.
(cont.) This combination is then used to demonstrate strong coupling at room temperature, as characterized by a light-matter coupling strength, Rabi-splitting, that significantly exceeds the dephasing processes competing against the coherence of the interaction. Finally, prospects of this approach for realizing a polariton laser at room temperature are considered, and improved microcavity architectures are demonstrated as a path towards its realization.
by Jonathan Randall Tischler.
Ph.D.
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Jaako, T. (Tuomas). "Validity of the semiquantum approximation in the ultrastrong coupling regime of cavity QED." Master's thesis, University of Oulu, 2015. http://urn.fi/URN:NBN:fi:oulu-201503171176.
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With the recent advancements made in the coupling of quantum systems, reaching the (ultra)strong coupling regime, where the coupling constant exceeds the dissipation rate and approaches the frequencies of the coupled systems, is getting closer. In this regime, the much used semiclassical model is no longer valid, and the solving of the full quantum master equation can be computationally too demanding. Thus, we must develop a new approach to be able to simulate the system.
One solution is to use the semiquantum approximation. In this thesis, we present a systematic way of employing the semiquantum approximation and compare it to the full master equation. Our aim is to determine the range for the coupling strength where the semiquantum model is applicable. We chose to do the comparison of the semiquantum approximation and the master equation within the Rabi model, which can be used to describe e.g. the interaction of light and matter. The Rabi model describes a system with a coupled two-level system and a harmonic oscillator. It was chosen because its behaviour is reasonably well known.
We compared the semiquantum approximation to the quantum master equation in two cases. First we studied the steady state results from the two models, and then moved on to the spectral properties. The results show that the steady state and the spectrum obtained from the semiquantum model agree with the ones obtained by using the master equation, until the coupling reaches a considerable fraction of the resonant frequency of the oscillator, while still exceeding the experimentally reasonable dissipation rate by an order of magnitude.
In the future, one could use the semiquantum approximation in the field of cavity optomechanics. There a mechanical oscillator is coupled to optical radiation confined in a cavity, e.g. a Fabry-Pérot cavity. Especially in optomechanics, the solving of the master equation can turn out to be a formidable task, and by using the semiquantum approximation one could reduce the computation time considerably.
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Cuthbert, J. A. "Massive quark self-energy in cavity QCD." Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/14412.
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Includes bibliographical references.The greatest obstacle in calculating the self-energy Feynman diagram is that it is, in principle, linearly divergent. So far the self-energy of a massive quark in cavity quantum chromodynamics has only been calculated for the lowest cavity mode ls1/2. The methods used so far, have been based on the multiple reflection formalism, in which the zero reflection term is extracted out analytically and evaluated separately using Pauli-Villars regularization. This thesis is based on the dimensional regularization scheme, adapted for use in the cavity, by Stoddart et al., who calculated the self-energy for a massless quark. This involves analytically isolating the divergences using dimensional regularization and then removing the divergences using the minimal subtraction (ms) scheme or some similar subtraction scheme. In this thesis, the self-energies of massive quarks have been calculated using the ms scheme for a number of low-lying cavity modes. The ls1/2 results have also been compared with the Pauli-Villars regularization scheme used by Goldhaber, Jaffe and Hansson.
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Page, Philip R. "The ratio gA/gV in cavity QCD." Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/17390.
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Bibliography: pages 96-98.BRS invariant quantum chromodynamics in a spherical cavity is developed using canonical quantization. The weak vector and axial form factors are defined, employing a classical external W- field. The Gell-Mann and Low theorem is extended to include non-diagonal matrix elements and degenerate perturbation theory. The Sucher form of the Gell-Mann and Low theorem is employed to calculate corrections of order GFg² in the weak and strong coupling constants to gA and gv for neutron beta decay. Up and down quarks are assumed massless. The gauge-independent divergences from the loop diagrams cancel each other and can be regularized dimensionally, making renormalization unnecessary. We find that the weak vector and axial current coupling constants are respectively: 9v = 1.0000 gA = 1.0883 + 0.2425 αs', where the preferred value of αs = 2.2 in the M.I.T. bag model gives gA = 1.62.
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Dmytruk, Olesia. "Quantum transport in a correlated nanostructure coupled to a microwave cavity." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS335/document.
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Dans cette thèse, nous étudions d’un point de vue théorique les propriétés physiques de nanostructures couplées à des cavités micro-ondes. L’électrodynamique quantique (QED) en cavité en présence d’une boîte quantique s’est révélée être une technique expérimentale puissante, permettant d'étudier cette dernière par des mesures photoniques en plus des mesures de transport électronique conventionnelles. Dans cette thèse, nous proposons d'utiliser le champ micro-ondes de la cavité afin d’extraire des informations supplémentaires sur les propriétés des conducteurs quantiques : le coefficient de transmission optique est directement lié à la susceptibilité électronique de ces conducteurs quantiques. Nous appliquons ce cadre général à différents systèmes mésoscopiques couplés à une cavité supraconductrice micro-ondes comme une jonction tunnel, une boîte quantique couplée à des réservoirs, un fil topologique et un anneau supraconducteur. La QED en cavité peut être utilisée pour sonder, par l'intermédiaire de mesures photoniques, la dépendance en fréquence de l’admittance du puits quantique couplé à la cavité micro-ondes. En ce qui concerne le fil topologique, nous avons montré que la cavité permet de caractériser la transition de phase topologique, l'émergence de fermions de Majorana, ainsi que la parité de l'état fondamental. Pour l'anneau supraconducteur, nous étudions par l'intermédiaire de la réponse optique de la cavité l’effet Josephson et le passage à l'effet Josephson fractionnaire, qui est associé à l'apparition de fermions de Majorana dans le système. Le cadre théorique proposé dans cette permet de sonder de manière non-invasive un large éventail de nanostructures, des boîtes quantiques aux supraconducteurs topologiques. En outre, il donne de nouvelles informations sur les propriétés de ces conducteurs quantiques, informations non accessibles via des expériences de transportIn this thesis, we study theoretically various physical properties of nanostructures that are coupledto microwave cavities. Cavity quantum electrodynamics (QED) with a quantum dot has been proven to be a powerful experimental technique that allows to study the latter by photonic measurements in addition to electronic transport measurements. In this thesis, we propose to use the cavity microwave field to extract additional information on the properties of quantum conductors: optical transmission coefficient gives direct access to electronic susceptibilities of these quantum conductors. We apply this general framework to different mesoscopic systems coupled to a superconducting microwave cavity, such as a tunnel junction, a quantum dot coupled to the leads, a topological wire and a superconducting ring. Cavity QED can be used to probe the finite frequency admittance of the quantum dot coupled to the microwave cavity via photonic measurements. Concerning the topological wire, we found that the cavity allows for determining the topological phase transition, the emergence of Majorana fermions, and also the parity of the ground state. For the superconducting ring, we propose to study the Josephson effect and the transition from the latter to the fractional Josephson effect, which is associated with the emergence of the Majorana fermions in the system, via the optical response of the cavity. The proposed framework allows to probe a broad range of nanostructures, including quantum dots and topological superconductors, in a non-invasive manner. Furthermore, it gives new information on the properties of these quantum conductors, which was not available in transport experiments
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Leach, Joseph R. "PHOTON STATISTICS AND FIELD-INTENSITY CORRELATION OF A CAVITY QED SYSTEM WITH EXTERNAL POTENTIALS." Miami University / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=miami1058466870.
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Yip, Ka Wa. "Optical pumping of multiple atoms in the single photon subspace of two-mode cavity QED." Miami University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=miami1438288697.
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Mazzei, Andrea. "Cavity enhanced optical processes in microsphere resonators." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15770.
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Diese Arbeit beschreibt eine ausfŸhrliche Untersuchung der physikalischen Eigenschaften von Mikrokugelresonatoren aus Quarzglas. Diese Resonatoren unterstŸtzen sogennante whispering-gallery Moden (WGM), die GŸten so hoch bis 109 bieten. Als experimentelle Hilfsmittel wurden ein Nahfeld- und ein Konfokalmikroskop benutzt, um die Struktur der Moden bezŸglich der Topographie des Resonators eindeutig zu identifizieren, oder um einzelne Quantenemitter zu detektieren und anzuregen. Die resonante †berhšhung des elektromagnetischen Feldes in den Moden des Resonators wurde ausgenutzt, um stimulierte Raman-Streuung mit extrem niedrigem Schwellenwert im Quarzglas zu beobachten. Ein Rekordschwellenwert von 4.5 Mikrowatts wurde gemessen. Mittels einer Nahfeldsonde wurde die Modenstruktur des Mikro-Ramanlasers gemessen. Mikroresonatoren stellen einen Grundbaustein der Resonator-Quantenelektrodynamik dar. In dieser Arbeit wurde die Kopplung von einem einzelnen strahlenden Dipol an die WGM sowohl theoretisch als auch experimentell untersucht. Die kontrollierte Kopplung von einem einzelnen Nanoteilchen an die WGM eines Mikrokugelresonators wurde nachgewiesen. Erste Ergebnisse in der Kopplung eines einzelnen Emitters an die Moden des Resonators wurden erzielt. Die resonante Wechselwirkung mit Resonatormoden wurde ausgenutzt, um den Photonentransfer zwischen zwei Nanoteilchen dramatisch zu verstŠrken. Schlie§lich wurde die bislang unbeachtete Analogie zwischen dem Quantensystem eines einzelnen Emitters in Wechselwirkung mit einer einzelnen Resonatormode und dem klassischen System zweier gekoppelten Moden experimentell untersucht. Es wurde bewiesen, wie die aus der Resonatorquantenelektrodynamik bekannten Kopplungsregime der starken und schwachen Kopplung in Analogie auch an einem klassischen System beobachtet werden kšnnen. Der †bergang von schwacher zu starker Kopplung wurde beobachtet, und bislang gemessene unerwartet hohe Kopplungsraten konnten einfach erklŠrt werden.This work presents an extensive study of the physical properties of silica microsphere resonators, which support whispering-gallery modes (WGMs). These modes feature Q-factors as high as 109 corresponding to a finesse of 3 millions for spheres with a diameter of about 80 micrometers. These are to date among the highest available Q-factors, leading to cavity lifetimes of up to few microseconds. A near-field microscope and a confocal microscope are used as tools to unequivocally identify the mode structure related to the sphere topography, and for excitation and detection of single quantum emitters. The high field enhancement of the cavity modes is exploited to observe ultra-low threshold stimulated Raman scattering in silica glass. A record ultra-low threshold of 4.5 microwatts was recorded. The mode structure of the laser is investigated by means of a near-field probe, and the interaction of the probe itself with the lasing properties is investigated in a systematic way. Microcavities also one of the building blocks of Cavity QED. Here, the coupling of a radiative dipole to the whispering-gallery modes has been studied both theoretically and experimentally. The controlled coupling of a single nanoparticle to the WGMs is demonstrated, and first results in coupling a single quantum emitter to the modes of a microsphere are reported. The resonant interaction with these modes is exploited to enhance photon exchange between two nanoparticles. Finally a novel analogy between a system composed of a single atom interacting with one cavity mode on one side and intramodal coupling in microsphere resonators induced by a near-field probe on the other side is presented and experimentally explored. The induced coupling regimes reflect the different regimes of weak and strong coupling typical of Cavity QED. The transition between the two coupling regimes is observed, and a previously observed unexpectedly large coupling rate is explained.
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Ballance, Timothy George. "An ultraviolet fibre-cavity for strong ion-photon interaction." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267687.
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We investigate the coupling of a single trapped ion to a miniature optical cavity operating in the ultraviolet. Our cavity provides a source of single photons at a high rate into a single spatial mode. Using our apparatus, we have demonstrated the highest atom-cavity coupling rate achieved with a single ion by an order of magnitude. When the ion is continuously excited, we observe phase-sensitive correlations between emission into free-space and into the cavity mode, which can be explained by a cavity induced back-action effect on a driven dipole. We demonstrate coherent manipulation of a hyperfine qubit and ultra-short optical π rotations, which are essential tools for creation and detection of spin-photon entanglement. To this end, we have developed optical fibre-based Fabry-Perot cavities in the ultraviolet spectral range. These cavities operate near the primary dipole transition of Yb at 370 nm, and allow us to couple a pure atomic two-level system offered by a single trapped ion to the cavity mode. A new Paul trap apparatus in an ultra-high vacuum chamber has been built which allows for the integration of these cavities at very small ion-mirror separations. In order for independent operation of the trap, a compact system of diode lasers has been built which are stabilised to low-drift optical reference cavities. Coherent control of the hyperfine qubit in Yb 171 is achieved through application of microwave radiation, and ultra-short optical π rotations are performed with resonant light pulses derived from a frequency-doubled mode-locked titanium-sapphire laser. The experiment is controlled through a system of hardware and software which has been developed in a modular fashion and will allow for efficient control on the nanosecond time-scale when several such systems are interconnected. The success of our system opens the door to future experiments with trapped ions which will reach the strong coupling regime with a single ion. Furthermore, when operated in the fast-cavity regime, systems based on our approach will enable high-efficiency collection of photons from the ion into the single mode of an optical fibre. These systems will allow for the generation of distributed entanglement and will prove ideal as nodes in a larger quantum network of trapped ions.
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Boca, Andreea Kimble H. Jeff. "Experiments in cavity QED : exploring the interaction of quantized light with a single trapped atom /." Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-05272005-163452.
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Lindebaum, R. J. "The anomalous magnetic moment of baryons in cavity QCD." Master's thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/17387.
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Bibliography: pages 86-87.Using a generalised form of the Gell-Mann and Low theorem, all the diagrams in cavity QCD to order as that contribute to the magnetic moment are calculated. The calculations are performed for massive quarks so a mass renormalisation scheme has been developed to cope with the new divergences this brings into the self-energy insert diagrams. The results of this work show that no improvement on the simple SU(3) model is made by including these corrections. These calculations point to a smaller value of αs than that which is usually used.
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O'Connor, M. S. "The anomalous magnetic moment of the nucleon in cavity QCD." Doctoral thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/17389.
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Bibliography: pages 71-72.Perturbative quantum chromodynamics is developed in a spherical cavity using a symmetric form of the Gell-Mann and Low theorem. This formalism allows one to generate any desired term in the perturbation series, in a manner which is similar to the familiar Feynman rules in free space. All corrections to order eg² in the electromagnetic and strong coupling constants which contribute to the magnetic moment of a baryon are generated using this formalism. The O(eg²) radiative corrections to the magnetic moment of the nucleon are calculated here in an arbitrary covariant gauge. The gauge-dependent parts are found to vanish identically, and the divergences arising from the loop diagrams cancel amongst each other, making renormalization unnecessary. However, it is shown here that one can, if it is necessary, remove the divergences from the cavity diagrams by subtracting from them a singular factor which is found using dimensional regularization in the analogous free-space diagrams.