Dissertations / Theses: 'Circuit quantum electrodynamics'

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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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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
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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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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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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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 priori. This work lays the foundation for future advancements in cavity centered quantum reservoir engineering protocols realizing hardware efficient circuit QED designs.

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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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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.

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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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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
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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Viehmann, Oliver [Verfasser], and Florian [Akademischer Betreuer] Marquardt. "Multi-qubit circuit quantum electrodynamics / Oliver Viehmann. Betreuer: Florian Marquardt." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/1042147558/34.

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Andersson, Gustav. "Circuit quantum electrodynamics with a transmon qubit in a 3D cavity." Thesis, KTH, Tillämpad fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168010.

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Viennot, Jeremie. "Charge and spin dynamics in a hybrid circuit quantum electrodynamics architecture." Phd thesis, Ecole Normale Supérieure de Paris - ENS Paris, 2014. http://tel.archives-ouvertes.fr/tel-01062841.

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Cette thèse étudie expérimentalement le mécanisme de couplage entre les degrés de liberté de charge et de spin dans des doubles boîtes quantiques et des cavités supraconductrices de grande finesse. Nous utilisons des nanotubes de carbone comme conducteurs cohérents pour nos boîtes quantiques. Nous avons conçu une expérience et développé de nouvelles méthodes de fabrication afin de pouvoir contrôler ces dispositifs. Avec ces méthodes, nous examinons le couplage résonant entre les transitions électroniques de charge dans les boîtes quantiques et la cavité micro-onde. Nous poussons le système hors équilibre pour caractériser sa dynamique et extraire ses paramètres intrinsèques. Nous étudions la possibilité d'un couplage de photons uniques avec un spin électronique individuel, en utilisant des champs effectifs non colinéaires induits par des interfaces ferromagnétiques comme ingrédient clef pour construire ce couplage. Les résultats préliminaires dans cette architecture en circuit sont prometteurs pour de futures expériences d'électrodynamique quantique en cavité avec des spins uniques.

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Elliott, Matthew. "Theory of nonclassical photonic states in driven-dissipative circuit quantum electrodynamics." Thesis, University of Surrey, 2017. http://epubs.surrey.ac.uk/841210/.

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Superconducting circuits provide an architecture upon which cavity quantum electrodynamics (QED) can be implemented at microwave frequencies in a highly tunable environment. Known as circuit QED, these systems can achieve larger nonlinearities, stronger coupling and greater controllability than can be achieved in cavity QED, all in a customisable, solid state device, making this technology an exciting test bed for both quantum optics and quantum information processing. These new parameter regimes open up new avenues for quantum technology, while also allowing older quantum optics results to finally be tested. In particular is is now possible to experimentally produce nonclassical states, such as squeezed and Schr\"odinger cat states, relatively simply in these devices. Using open quantum systems methods, in this thesis we investigate four problems which involve the use of nonclassical states in circuit QED. First we investigate the effects of a Kerr nonlinearity on the ability to preserve transported squeezed states in a superconducting cavity, and whether this setup permits us to generate, and perform tomography, of a highly squeezed field using a qubit, with possible applications in the characterisation of sources of squeezed microwaves. Second, we present a novel scheme for the amplification of cat states using a coupled qubit and external microwave drives, inspired by the stimulated Raman adiabatic passage. This scheme differs from similar techniques in circuit QED in that it is deterministic and therefore compatible with a protocol for stabilising cat states without the need for complex dissipation engineering. Next we use solutions of Fokker-Planck equations to study the exact steady-state response of two nonlinear systems: a transmon qubit coupled to a readout resonator, where we find good agreement with experiments and see simultaneous bistability of the cavity and transmon; and a parametrically driven nonlinear resonator, where we compare the classical and quantum phases of the system and discuss applications in the generation of squeezed states and stabilisation of cat states. Finally, we investigate the use of two different types of superconducting qubits in a single experiment, seeing that this enables engineering of the self- and cross-Kerr effects in a line of cavities. This could provide a valuable means of entangling cavity states, in addition to a resource for quantum simulation.

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Ohm, Christoph [Verfasser], Fabian [Akademischer Betreuer] Hassler, Thomas [Akademischer Betreuer] Schmidt, and David [Akademischer Betreuer] DiVincenzo. "Quantum measurements in Majorana circuit quantum electrodynamics / Christoph Ohm ; Fabian Hassler, Thomas Schmidt, David DiVincenzo." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1130871703/34.

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Govia, Luke Colin Gene [Verfasser], and Frank [Akademischer Betreuer] Wilhelm-Mauch. "Qubit and cavity measurement in circuit quantum electrodynamics / Luke Colin Gene Govia. Betreuer: Frank Wilhelm-Mauch." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2015. http://d-nb.info/1077211627/34.

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Mariantoni, Matteo [Verfasser]. "New Trends in Superconducting Circuit Quantum Electrodynamics: Two Amplifiers, Two Resonators, and Two Photons : A Not So Short Introduction to Quantum Circuits and Signals / Matteo Mariantoni." Aachen : Shaker, 2010. http://d-nb.info/108453651X/34.

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Hoffmann, Elisabeth [Verfasser], Rudolf [Akademischer Betreuer] Gross, and Jonathan J. [Akademischer Betreuer] Finley. "Experiments on Two-Resonator Circuit Quantum Electrodynamics: A Superconducting Quantum Switch / Elisabeth Hoffmann. Gutachter: Rudolf Gross ; Jonathan J. Finley. Betreuer: Rudolf Gross." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1036495086/34.

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Hoffmann, Elisabeth Verfasser], Rudolf [Akademischer Betreuer] [Gross, and Jonathan J. [Akademischer Betreuer] Finley. "Experiments on Two-Resonator Circuit Quantum Electrodynamics: A Superconducting Quantum Switch / Elisabeth Hoffmann. Gutachter: Rudolf Gross ; Jonathan J. Finley. Betreuer: Rudolf Gross." München : Universitätsbibliothek der TU München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:91-diss-20130603-1140394-0-5.

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Leib, Martin [Verfasser], Michael J. [Akademischer Betreuer] Hartmann, and Wilhelm [Akademischer Betreuer] Zwerger. "Many-Body Physics with Circuit Quantum Electrodynamics / Martin Leib. Gutachter: Wilhelm Zwerger ; Michael J. Hartmann. Betreuer: Michael J. Hartmann." München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/1070624292/34.

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Peterer, Michael. "Experiments on multi-level superconducting qubits and coaxial circuit QED." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:572f08ef-2d14-4fda-8e18-71f80fc4c47a.

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Superconducting qubits are a promising technology for building a scalable quantum computer. An important architecture employed in the field is called Circuit Quantum Electrodynamics (circuit QED), where such qubits are combined with high quality microwave cavities to study the interaction between artificial atoms and single microwave photons. The ultra-strong coupling achieved in these systems allows for control and readout of the quantum state of qubits to perform quantum information processing. The work on circuit QED performed in this thesis consisted of realizing an experimental setup for qubit experiments in a new laboratory, investigating the coherence and decay of higher energy levels of superconducting transmon qubits and finally demonstrating a novel coaxial form of circuit QED. Designing and building a 3D circuit QED setup involved the following main accomplishments: producing high quality 3D cavities; designing and installing the cryogenic microwave setup as well as the room temperature amplification and data acquisition circuitry; successfully developing a recipe for the fabrication of Josephson junctions; controlling and measuring superconducting 3D transmon qubits at 10mK. Several qubits were fully characterised and have shown coherence times of several microseconds and relaxation times up to 25μs. Superconducting qubits in fact possess higher energy levels that can provide significant computational advantages in quantum information applications. In experiments performed at MIT, preparation and control of the five lowest states of a transmon qubit was demonstrated, followed by an investigation of the phase coherence and decay dynamics of these higher energy levels. The decay was found to proceed mainly sequentially with relaxation times in excess of 20μs for all transitions. A direct measurement of the charge dispersion of these levels was performed to explore their characteristics of dephasing. This experiment was also reproduced on a 3D transmon fabricated and measured in Oxford, where due to a higher effective qubit temperature a multi-level decay model including thermal excitations was developed to explain the observed relaxation dynamics. Finally, a coaxial transmon, which we name the coaxmon, is presented and measured with a coaxial LC readout resonator and input/output coupling ports placed inline along the third dimension. This novel coaxial circuit QED architecture holds great promise for developing a scalable planar grid of qubits to build a quantum computer.

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Baust, Alexander Theodor [Verfasser], Rudolf [Akademischer Betreuer] Gross, and Jonathan J. [Akademischer Betreuer] Finley. "Tunable Coupling and Ultrastrong Interaction in Circuit Quantum Electrodynamics / Alexander Theodor Baust. Gutachter: Rudolf Gross ; Jonathan J. Finley. Betreuer: Rudolf Gross." München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/1072758237/34.

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Baust, Alexander Theodor Verfasser], Rudolf [Akademischer Betreuer] [Gross, and Jonathan J. [Akademischer Betreuer] Finley. "Tunable Coupling and Ultrastrong Interaction in Circuit Quantum Electrodynamics / Alexander Theodor Baust. Gutachter: Rudolf Gross ; Jonathan J. Finley. Betreuer: Rudolf Gross." München : Universitätsbibliothek der TU München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:91-diss-20150611-1252065-1-0.

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Aiello, Gianluca. "Quantum dynamics of a high impedance microwave cavity strongly coupled to a Josephson junction." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP089.

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Le but de cette thèse est d'étudier les propriétés et la dynamique d'une cavité micro-onde à haute impédance couplée galvaniquement à une jonction Josephson polarisée en tension. La cavité est réalisée en aluminium granulaire, un supraconducteur désordonné à haute inductance cinétique, qui nous a permis d'obtenir des modes avec un facteur de qualité élevé (jusqu'à 30 000) et une grande impédance caractéristique allant jusqu'à 5 kOhm dans la gamme du GHz. L'occupation et les propriétés des modes de la cavité sont fortement influencées par les processus tunnel se produisant dans la jonction connectée à la cavité. Comme l'impédance caractéristique des modes est comparable au quantum de résistance, des processus non linéaires d'ordre élevé sont observés. À basse tension par rapport au gap supraconducteur de la jonction, le processus dominant est le passage tunnel inélastique des paires de Cooper, qui peuple les différents modes de la cavité. Nous mesurons directement l'émission de photons dans un mode à 6 GHz et observons plus de 70 pics d'émission en fonction de la tension de polarisation, une signature claire de la non-linéarité élevée. Aux tensions plus élevées proches du gap, le tunneling des quasi-particules domine. Ce processus dissipatif modifie à la fois la fréquence de résonance et la largeur des modes. Un traitement quantique de ce processus dissipatif en termes de décalage de Lamb et de sauts quantiques est nécessaire pour expliquer quantitativement nos mesures. Ces résultats montrent le potentiel de l'aluminium granulaire pour réaliser des expériences d'optique quantique dans un régime où le transport de charge et les photons micro-ondes sont fortement couplés
The purpose of this thesis is to investigate the properties and the dynamics of a high impedance microwave cavity galvanically coupled to a DC biased Josephson junction. The cavity is realized in granular Aluminum, a disordered superconductor with high kinetic inductance, which allowed us to obtain modes with a high quality factor (up to 30000) and a large characteristic impedance up to 5 kOhm in the GHz range. The occupation and the properties of the cavity modes are strongly affected by the charge tunneling processes occurring in the junction connected to the cavity. Because the characteristic impedance of the modes is comparable to the quantum of resistance, high order non-linear processes are observed. At low voltages compared to the superconducting gap of the junction, the dominant process is the inelastic tunneling of Cooper pairs, which populates the different cavity modes. We directly measure the photon emission in one mode at 6 GHz and observe more than 70 emission peaks as a function of bias voltage, a clear signature of the high non-linearity. At larger voltages close to the gap, quasiparticle tunneling dominates. This dissipative process modifies both the resonance frequency and the linewidth of the modes. A quantum treatment of this dissipative process in terms of Lamb shift and quantum jumps is required to quantitatively explain our measurements. These results show the potential of granular Aluminum to realize microwave quantum optics experiments in a regime where charge transport and microwave photons are strongly coupled

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Prance, H. "Quantum electrodynamic duality in superconducting weak link circuits." Thesis, University of Sussex, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370437.

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Bruhat, Laure. "Microwaves as a probe of quantum dot circuits : from Kondo dynamics to mesoscopic quantum electrodynamics." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEE012/document.

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Cette thèse utilise les micro-ondes pour étudier des circuits de boîtes quantiques à base de nanotubes de carbone. Dans une première expérience, l'excitation micro-onde est appliquée directement sur une électrode du circuit pour une boîte quantique dans le régime Kondo. Nous réalisons la première caractérisation fréquence-amplitude de la conductance Kondo à biais nul. Des données préliminaires sont en accord avec la prédiction d'universalité. Nous présentons deux autres expériences, où les boîtes quantiques sont insérées dans des résonateurs micro-ondes. Les photons de la cavité sondent la résistance de relaxation de charge et l'émission de photons dans une boîte quantique couplée à des réservoirs normaux et supraconducteurs, en présence de répulsion coulombienne. Nos observations valident une modélisation en termes de réponse linéaire du circuit. Nous présentons aussi la première implémentation d'une lame séparatrice à paires de Cooper en cavité. Le régime de couplage fort est atteint, une première avec des circuits de boîtes quantiques. Nos résultats renforcent l'idée que l'électrodynamique quantique mésoscopique est une boîte à outils fructueuse, aussi bien dans le contexte du domaine du transport quantique que dans celui de l'information quantique
This thesis uses microwaves as probe of carbon nanotube quantum dot circuits. In a first experiment, a microwave excitation is directly applied to a circuit electrode for a quantum dot in the Kondo regime. We provide the first frequency-amplitude characterisation of the Kondo zero-bias conductance. Preliminary data are consistent with predicted universal behaviour. We present two other experiments, where quantum dot circuits are embedded in microwave resonators. Cavity photons probe charge relaxation resistance and photon-emission in a quantum dot coupled to normal and superconducting reservoirs in presence of Coulomb repulsion. Our observations validate a modelling in terms of the circuit linear response. We also present the first implementation of a Cooper pair splitter in cavity. The strong coupling regime is achieved, a premiere with quantum dot circuits. Our findings support the idea, that mesoscopic quantum electrodynamics is a fruitful toolbox in the context of both fields of quantum transport and quantum information science

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André, Stephan [Verfasser], and G. [Akademischer Betreuer] Schön. "Quantum electrodynamics with superconducting circuits: Effects of dissipation and fluctuations / Stephan André. Betreuer: G. Schön." Karlsruhe : KIT-Bibliothek, 2012. http://d-nb.info/1023905841/34.

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Sá, Neto Olímpio Pereira de 1984. "Codificação de bits quânticos via eletrodinâmica quântica de cavidades em circuitos." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278331.

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Orientador: Marcos Cesar de Oliveira
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
Made available in DSpace on 2018-08-14T22:41:50Z (GMT). No. of bitstreams: 1 SaNeto_OlimpioPereirade_M.pdf: 2183642 bytes, checksum: 1db9639afd1e7c5b802c3e8608ea049f (MD5) Previous issue date: 2009
Resumo: Nesta dissertação de mestrado foi analisada a eficiência de um esquema de codificação específico de bits quânticos em estados de campos eletromagnéticos quânticos em linhas de transmissão coplanares acopladas a um dispositivo supercondutor, o "Átomo Artificial", sob a ação de um banho ôhmico. O objetivo central desta pesquisa é estudar a Eletrodinâmica Quântica de Cavidades, bem como aspectos de implementação de dispositivos para computação quântica. Neste contexto, nossa proposta de pesquisa consiste em estudar um esquema prático de processamento de informação eficiente, explorando recursos físicos de um sistema real
Abstract: In this dissertation we analyse the efficiency of a specific quantum bit encoding in a quantum electromagnetic field state prepared in a coplanar transmission line coupled to a single superconducting device, the "Artificial Atom", under action of external noise sources affecting the efficiency of the device. The central objective is to study the circuit cavity quantum electrodynamics and to propose practical aspects of devices for quantum computation implementation
Mestrado
Física
Mestre em Física

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Al-Khawaja, Sameer. "Time dependent phenomena in squid ring circuits." Thesis, University of Sussex, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298105.

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Desjardins, Matthieu. "Exploring quantum circuits with a cQed architecture : application to compressibility measurements." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEE044/document.

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Les circuits électroniques mesurés à des températures cryogéniques permettent d'étudier le comportement quantique des électrons. En particulier, les circuits de boites quantiques sont des systèmes accordables modèles pour l'étude des électrons fortement corrélés, symbolisée par l'effet Kondo. Dans cette thèse, des circuits de boîtes quantiques à base de nanotube de carbone sont intégrés à des cavités micro-onde coplanaires, avec lesquelles l'électrodynamique quantique en cavité (cQED) a atteint un degré de contrôle remarquable de l'interaction lumière-matière. Les photons de la cavité micro-onde sont ici utilisés pour sonder la dynamique de charge dans le circuit de boîtes quantiques. Plus précisément, la cavité micro-onde de grande finesse nous a permis de mesurer la compressibilité du gas d'électrons dans une boîte avec une sensibilité sans précédent. Des mesures simultanées de transport électronique et de la compressibilité montrent que la résonance Kondo observées dans la conductance est transparente aux photons micro-ondes. Cela révèle le gel de la dynamique de charge dans la boîte quantique pour ce mécanisme particulier de transport d'électrons et illustre que la résonance Kondo à N-corps dans la conductance est associée aux corrélations issues des fluctuations de spin d'une charge gelée. Nous étudions aussi dans cette thèse la possible émergence d'une nouvelle quasi-particule, appelée état lié de Majorana, et qui serait sa propre anti-particule. Dans ce but, une grille ferromagnétique a été placée sous le nanotube pour créer un couplage spin-orbit artificiel. L'observation d'états d'Andreev dans un tel dispositif est un premier pas prometteur vers la détection avec une architecture cQED d'états liés de Majorana dans les nanotubes de carbone
On-chip electronic circuits at cryogenic temperature are instrumental to studying the quantum behavior of electrons. In particular, quantum dot circuits represent tunable model systems for the study of strong electronic correlations, epitomized by the Kondo effect. In this thesis, carbon nanotube based-quantum dot circuits are embedded in coplanar microwave cavities, with which circuit quantum electrodynamics (cQED) has reached a high degree of control of the light-matter interaction. Here, microwave cavity photons are used to probe the charge dynamics in the quantum dot circuit. More precisely, the high finesse cavity allows us to measure the compressibility of the electron gas in the dot with an unprecedented sensitivity. Simultaneous measurements of electronic transport and compressibility show that the Kondo resonance observed in the conductance is transparent to microwave photons. This reveals the predicted frozen charge dynamics in the quantum dot for this peculiar electron transport mechanism and illustrates that the many-body Kondo resonance in the conductance is associated to correlations arising from spin fluctuations of a frozen charge. A second quantum phenomenon addressed in this thesis is the possible emergence of a new quasi-particle in condensed matter, called Majorana bound state, which would be its own anti-particle. For that purpose, a ferromagnetic gate has been placed below a nanotube in order to generate a synthetic spin-orbit coupling. The observation of Andreev bound states in such a device is a first promising step towards the detection with a cQED architecture of Majorana bound states in a carbon nanotube

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Hsu, Chi-Wen, and 徐啟文. "Setup microwave measurement system for circuit-Quantum electrodynamics experiment." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/tv4rkv.

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碩士
國立清華大學
物理學系
106
In recent years, quantum computers and quantum computing have become the important scientific and technological development directions and the development of Quantum bit (qubit) is the core of the quantum technology. The operation of qubits depends on the interaction between artificial atoms and photons, the quantum state needs to be operate in an ultra-low temperature environment (approximately 10 mK) and precision microwave manipulation techniques. The purpose of this dissertation is mounting the cryogenic measurement system for qubits experiment and the resonant cavity design. The experiment in the thesis uses a dilution refrigerator as a cryogenic system to lower the system temperature to 10 mK sample space through the multiple descending temperature layers. In the process, mount attenuator at the input to reduce heat conduction and noise. When the microwave signal is output from the 10 mK space, superconducting transmission line use first to avoid the noise interference, then the low temperature amplifier performs the first amplification to separate the signal from noise, and then the room temperature amplifier outside the fridge perform the secondary amplification. According to the general transition frequency of the artificial atom process, the operating frequency band of the measurement system is set at 4~12 GHz. The low temperature amplifier is a device most likely to affect the signal. Therefore, we use a 50 ohms resistor to measure the noise temperature from the low temperature amplifier, and estimate the noise. In order to enhance the coupling effect with photons, we put the artificial atoms in the resonant cavity. In this article, we focus on the measurement of two-dimensional coplanar waveguide (thanks to dr. J.W. Wang, a former laboratory member for the design and the simulation data) and design, simulate by HFSS and measurement of 3D cavity. The resonant frequency of the two-dimensional coplanar waveguide in the experiment is 8.24 GHz, and the sample is a semiconductor artificial atom, the experiment only measures the quality factor and resonant frequency of the cavity under T=10 mK. In order to cover the 4 to 12 GHz operating frequency band of the system, I designed 3D cavity with four resonance frequencies with copper and aluminum two different materials. At present, three groups of low temperature data have been measured, the photon loss rate of the 3D cavity in this paper compared with the literature that has achieved a strong coupling effect, we considered that there is an electromagnetic field environment that can make artificial atoms and photons strongly coupled.

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Chang, Yu-Cheng, and 張佑誠. "Superconducting Tunnel Junctions for Refrigeration Applications in Circuit Quantum Electrodynamics." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/yvraky.

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博士
國立臺灣大學
物理學研究所
107
Circuit quantum electrodynamics has flourished in recent years. It provides a platform for studying fundamental physics that helps to extend the concept of process, design and integration of integrated circuits. It has been applied to the areas of versatile quantum sensing as well as superconducting quantum computing. However, these applications require an ultralow temperature environment – any heat source that raises the electron temperature can induce error. Therefore, a quantum refrigerator capable of proving electron cooling plays a crucial role in the circuit quantum electrodynamic system. To realise the quantum refrigerator, we propose and demonstrate a clear, step-bystep scheme. Step I, tunable photonic heat transport in a quantum heat valve. II, design of the coupling between the heat reservoir and superconducting coplanar waveguide (CPW) resonator. III, photonic heat rectifier. IV, Implantation of Otto refrigerator. In this thesis, we will discuss the realisation of this scheme, including step I and II. We study heat transport through an assembly consisting of a superconducting qubit capacitively coupled between two nominally identical coplanar waveguide resonators, each equipped with a heat reservoir in the form of a normal-metal mesoscopic resistor termination. We report the observation of tunable photonic heat transport through this resonator–qubit–resonator assembly, and find that the reservoir-reservoir heat flux depends on the ratio of the qubit–resonator and the resonator–reservoir coupling strengths. The assembly displays qualitatively different behaviours in different coupling regimes. Our quantum heat valve is relevant for the realisation of quantum heat engines and refrigerators, which can be obtained, for example, by exploiting the time-domain dynamics and coherence of driven superconducting qubits. This effort would ultimately bridge the gap between the fields of quantum information and thermodynamics of mesoscopic systems. Characterisation of the coupling strength between a coplanar waveguide resonator and the heat reservoir is a prerequisite for understanding and implementation of this hybrid assembly. Due to the need of a highly dissipative channel, the quality factor of the resonator is inevitably low. In this thesis, we also present a method for determination of the quality factor of a resonator coupled strongly to the heat reservoir and experiments on λ/4 superconducting niobium CPW resonators terminated at the antinode by a dissipative copper microstrip via an aluminium lead. The dissipation of these resonators is high so that it is not possible to determine their very low quality factors using the conventional transmission spectrum analysis technique. Our method involves a comparison of the transmission characteristics above and below the superconducting transition of the aluminium lead, which enable us to identify the resonance. This method is experimentally verified with increasing thicknesses of the copper microstrips from 50 nm to 150 nm, which results in quality factors of 10~67, as expected from our calculations.

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30

Helmer, Ferdinand [Verfasser]. "Quantum information processing and measurement in circuit quantum electrodynamics / vorgelegt von Franz Ferdinand Helmer." 2009. http://d-nb.info/995522847/34.

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Chen, Ze-Yan, and 陳則言. "Coherent interaction between superconducting qubits and photons in circuit quantum electrodynamics." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/25885862987882674463.

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碩士
國立臺灣大學
物理學研究所
104
Coherent interaction between two superconducting transmon qubits and an on-chip microwave cavity is studied. Each transmon consists a flux-tuned Josephson junction and a shunting multi-finger capacitor, which is for reducing the effective charging energy of the transmon so as to suppress the noise induced by the charge fluctuation. Our microwave cavity is a half-wavelength coplanar waveguide made of Nb with resonance frequency of 5.96GHz. With no flux bias, the transition frequencies of each transmon are 10.1GHz and 9.3GHz respectively. They can be tuned to meet the cavity resonance frequency by increasing the flux bias. In our experiment, anticrossing features appear around qubit-cavity zero detuning points, showing the coherent interaction between qubits and the cavity. By fitting the anticrossing features around the cavity resonance with the Jaynse-Cummings model, the qubit-cavity coupling strengths of the two transmons are estimated to be 165MHz and 160MHz, respectively. According to this information, we also located the qubit-qubit zero detuning points, where another anticrossing features are shown. They are corresponding to the entanglement of the two transmons due to the effective qubit-qubit interaction.

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32

"Control of transverse optical patterns in semiconductor quantum well microcavities." 2012. http://library.cuhk.edu.hk/record=b5549072.

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全光信息處理被認為是其中一種改善當今計算機網絡性能的方法。而高效率的全光信息處理需要使用可用低強度的控制激光來控制的全光學開關。最近有人提出利用橫向光學圖案製造低強度全光學開關，並已通過原子蒸氣系統的實驗證明這個計劃的可行性。此外，相關的研究正在半導體量子阱微腔中進行。
這篇論文以微觀多體理論研究被激光正向入射的半導體量子阱微腔系統中產生的自發性橫向光學圖案。入射光會在一定條件下於半導體量子阱微腔中發生極化子場之間的自發四波混頻，並產生橫向光學圖案。我們分別以半分析和數值模擬的方法研究這些圖案的形成和選擇方式。本論文亦研究了如何用離軸激光和腔的各向異性來控制這些圖案。
我們分別用「多-
Processing information all-optically is thought to be one way to improve the performance of present-day computational network. Low intensity all-optical switches are desirable for effective all-optical information processing. Recently, low intensity all-optical switching schemes utilizing transverse optical patterns have been proposed. One such scheme was successfully demonstrated experimentally in an atomic vapour system, and a similar scheme is being studied both theoretically and experimentally in semiconductor quantum well micro-cavities.
In this thesis, we present our theoretical studies on the spontaneous transverse optical patterns produced by a semiconductor quantum well microcavity, pumped by a normally incident laser, using a microscopic many-body theory. Far field transverse optical patterns are formed under certain conditions by spontaneous four-wave mixing of the exciton-photon polariton field. The formation and the selection of these patterns are studied by both semi-analytical calculations and numerical simulations. The controls of transverse patterns using anisotropy in the microcavity and an o-axis control beam are also being studied in this thesis.
Two reduced models, the ‘multi-
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Luk, Ming Ho = 對半導體量子阱微腔中橫向光學圖案的控制 / 陸名浩.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2012.
Includes bibliographical references (leaves 136-141).
Abstracts also in Chinese.
Luk, Ming Ho = Dui ban dao ti liang zi jing wei qiang zhong heng xiang guang xue tu an de kong zhi / Lu Minghao.
Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- Pattern formation and nonlinear optics --- p.5
Chapter 1.2 --- All-optical switching --- p.8
Chapter 1.3 --- Semiconductor quantum well microcavity --- p.9
Chapter 2 --- Semiconductor quantum well microcavity --- p.13
Chapter 2.1 --- The structure of semiconductor quantum well microcavity --- p.14
Chapter 2.2 --- Coupling between the cavity mode and external fields --- p.18
Chapter 2.3 --- Microscopic theory in the microcavity --- p.22
Chapter 3 --- Linear stability analysis and reduced models --- p.32
Chapter 3.1 --- Pump only system - steady state solution --- p.32
Chapter 3.2 --- Pump only system - stability analysis --- p.37
Chapter 3.3 --- Off-axis stability studies --- p.39
Chapter 3.3.1 --- Stability analysis without phase-space filling --- p.40
Chapter 3.3.2 --- Linear stability analysis with phase-space filling --- p.54
Chapter 3.4 --- Reduced models --- p.59
Chapter 3.4.1 --- The multi- --- p.63
Chapter 3.4.2 --- The ring model --- p.68
Chapter 3.5 --- Effects of system parameters --- p.71
Chapter 3.5.1 --- Radiative loss --- p.72
Chapter 3.5.2 --- Incident laser field/intensity --- p.73
Chapter 3.5.3 --- Fluctuations/weak constant sources --- p.78
Chapter 4 --- Single-hexagon model --- p.82
Chapter 4.1 --- Numerical results of single-hexagon model --- p.82
Chapter 4.2 --- Pattern and time scale variations with parameters --- p.86
Chapter 4.2.1 --- Anisotropy in the cavity mode energy --- p.87
Chapter 4.2.2 --- Control beam intensity --- p.90
Chapter 5 --- Dynamical analysis and interplay of wave-mixing processes --- p.93
Chapter 5.1 --- Dynamical analysis --- p.93
Chapter 5.2 --- Interplay of wave mixing processes --- p.99
Chapter 5.3 --- Switching between hexagons --- p.103
Chapter 6 --- Full two-dimensional simulation --- p.111
Chapter 6.1 --- Convolution theorem and Fast Fourier Transform --- p.112
Chapter 6.2 --- Simulation result and difficulties --- p.114
Chapter 7 --- Other approaches --- p.119
Chapter 7.1 --- Real Space Simulation --- p.119
Chapter 7.2 --- Mode competition model --- p.121
Chapter 7.3 --- Transfer Matrix --- p.123
Chapter 8 --- Conclusion and outlook --- p.125
Chapter 8.1 --- Future work --- p.128
Chapter 8.1.1 --- Double Cavities --- p.128
Chapter 8.1.2 --- The Gross-Pitaevskii Equation and Bose-Einstein Condensation --- p.131
Bibliography --- p.136
Chapter A --- Dispersion of cavity photon --- p.142

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