Cette thèse présente le travail expérimental effectué pour observer la dynamique quantique de Zénon (QZD) dans une architecture 'circuit-QED' tridimentionnelle fonctionnant à très basse température. Dans cette architecture, un circuit supraconducteur de type transmon, jouant le rôle d'un atome artificiel, est couplé au champ électromagnétique d'une cavité microonde. Les niveaux d'énergie de l'atome et de la cavité sont alignés d'une nouvelle manière, afin de manipuler les états de Fock individuels de la cavité, tout en minimisant sa non-linearité Kerr induite par le transmon. La dynamique Zénon est obtenue en pilotant classiquement le champ de la cavité, tout en excitant fortement une transition inter-niveaux d'énergie du transmon, conditionnée à un état de Fock particulier. Ce forcage maintient la population de l'état de Fock à zéro, et conduit à la dynamique Zeno. Cette dynamique est observée par mesure de sa fonction de Wigner à intervalles de temps réguliers, soit par tomographie de Wigner, soit par tomographie quantique standard et reconstruction de la matrice densité. Nous observons trois exemples de QZD, et analysons la décohérence observée à l'aide simulations quantiques du système. / This thesis presents experimental work aimed at observing the quantum Zeno dynamics (QZD) in 3D circuit-QED, where an artificial atom, consisting of a superconducting circuit called a transmon, is coupled to the electric field of a microwave cavity resonator. The transmon and resonator energy levels are aligned in a novel way enabling the manipulation of individual Fock states of the cavity, while minimizing its transmon-induced Kerr non-linearity. We induce the QZD by displacing classically the cavity field while continuously driving strongly a transmon transition specific to a particular Fock state, which keeps this Fock state population at zero. The QZD is then observed by measuring the Wigner function of the fields at regular time intervals, either by Wigner tomography or standard quantum tomography and reconstruction of the density matrix. We observe three examples of QZD, and analyze the observed decoherence with the help of quantum simulations of the system.

In 1998, Florida voters approved Article V, Revision 7, which changed the funding mechanism of the state circuit court system from a county/state mix to state responsibility. The change was implemented as planned in the 2004/05 fiscal year. Although increased efficiency was a key goal of Revision 7, to date no published studies exist on the impacts of Revision 7 on circuit or system efficiency and/or productivity. This work analyzes Revision 7, integrating the larger debate of increasing judgeships or improving efficiency. The study is a full performance analysis of the Florida circuit courts from 1993 through 2008 that can benchmark the system‟s future efficiency and productivity. In that respect, top performers are identified. The study follows the evolution of court studies from their rational origins to the more recent orientation of open-natural systems. Resource dependency and institutional theory, two open-natural system frameworks, are utilized to predict that Florida‟s circuit courts have become more efficient over the period since the implementation of Revision 7. The efficiency outcomes are expected to be unequal across circuit sizes. Integrating a Florida debate to a larger one that transcends time and culture, productivity changes are expected to be a function of the number of judges that a circuit adds within a given year, controlling for other factors. The results of the study methodologies—data envelopment analysis, Malmquist Productivity Index, hierarchal regression analysis and analysis of covariance—reveal that only 3 of 300 DMU‟s in Florida are technically efficient; the mean IOTA score is .76. The Florida circuits did not improve efficiency and productivity as expected, in fact becoming significantly less efficient over time as a function of Revision 7. Small and medium-sized circuits lost iii efficiency, large circuits showed no change and there was a significant interaction between circuit size and Revision 7 period. Within the system overall, productivity fell by 2.7%, most noticeably in the small and medium-sized circuits. The number of judges a circuit added explained 32.2% of the variance in total factor productivity change. The largest system productivity losses followed both Revision 7 intervention years and the addition of the most judges in a single year. Analysis of covariance revealed that productivity increased only when no judges were added to a circuit, regardless of circuit size or time period (+2.6%). The addition of a single judge reduced average productivity by 8.6%; adding two judges reduced productivity by 10.5% and adding 3 or more judges reduced productivity by 16.2%. As judges were added, productivity declined in circuits of all sizes, but the drop was more pronounced in the small and medium-sized circuits. None of the circuits showed an increase in productivity from 1993 to 2008. Revision 7 has not increased circuit court efficiency or productivity in Florida. It is recommended that efficiency and productivity analyses be included in resource allocation decisions such as adding judgeships. More data on court structures and process are needed. Efficiency and productivity measures show that the current level of circuit court judgeships is sufficient.

This thesis presents the analysis and characterization of a low sensitivity dual feedback active RC bandpass filter. Chapter 2 details the analysis of the network and a method of simplifying the resultant transfer function by a single pole/zero cancellation. Chapter 3 characterizes the simplified transfer function through an analysis of the quality factor and of the center frequency gain as functions of the individual variables of the circuit. It also details sensitivity analyses of these characteristic quantities and a stability analysis. Lastly, chapter 3 presents graphical representations of the equations developed so that they can be used as design tools. It then goes through the details of applying these graphs to an example network. Chapter 4 explains the differences between experimental data and predicted data by discussing some of the nonlinearities neglected in the original analysis. Finally chapter 5 restates the design technique in light of the predominant nonlinearities.

L'électrodynamique quantique en guide d'onde étudie le comportement de circuits électriques supraconducteurs composés entre autres de jonctions Josephson et de lignes à transmission. Ces circuits présentent peu de pertes puisqu'ils sont supraconducteurs. De plus, grâce à la non-linéarité des jonctions Josephson, ils peuvent présenter des comportements typiquement quantiques. Dans cette thèse, nous élaborons un cadre théorique qui permet de traiter la connexion entre les lignes à transmission et les éléments de circuits localisés (lumped element). Nous présentons ensuite la théorie d'entrée-sortie dans le contexte de ce cadre théorique. Comme son nom l'indique, celle-ci lie les observables à la sortie du circuit à celles à son entrée et elle permet de faire des prédictions expérimentales. Nous obtenons aussi une équation maîtresse qui décrit le circuit lorsque l'information contenue dans les lignes à transmission est perdue ou ignorée. Nous utilisons le cadre théorique développé pour étudier la situation où deux circuits qui se comportent chacun comme un atome sont connectés à une ligne à transmission. Nous montrons que la physique dans ce type de système dépend de la distance entre les deux atomes artificiels. Lorsque la distance est telle que la phase [phi] acquise par le champ électromagnétique entre les deux atomes artificiels est un multiple entier de [pi], on observe qu'une superposition d'états particulière des atomes est couplée à la ligne à transmission. On dit que cet état est brillant tandis que l'autre état est dit sombre. Lorsque la phase [phi] acquise par le champ électromagnétique est un multiple impair de [pi]/2, on observe plutôt une interaction cohérente entre les deux atomes artificiels. Nous suggérerons des protocoles pour observer des signatures expérimentales de cette physique. Nous présentons des résultats expérimentaux obtenus suite à ces prédictions par nos collègues du groupe d'Andreas Wallraff à Zurich. Ces résultats confirment la théorie. Parmi ces données, on retrouve la première mesure d'une signature claire de l'interaction cohérente entre deux atomes. Nous utilisons aussi le cadre théorique développé pour étudier des circuits dans lesquels les inductances dépendent du temps. Nous nous intéressons à ces circuits puisqu'ils sont généralement non réciproque, ce qui en fait des candidats idéaux pour implémenter des circulateurs. Ces dispositifs qui permettent d'obtenir un couplage unidirectionnel entre deux circuits sont généralement réalisés à l'aide d'aimants. Ainsi, un défi important du domaine est de concevoir un circulateur qui peut s'intégrer à un circuit supraconducteur. On utilise notre cadre théorique pour décrire les circuits avec des inductances variables à l'aide d'un opérateur de transfert qui relient les entrées du circuit à ses sorties. Cet objet permet d'extraire les conditions sous lesquelles ce type de circuit se comporte comme un circulateur. On utilise aussi l'opérateur de transfert pour étudier un modèle de circuit qui sera testé sous peu par nos collaborateurs de JILA dans le but d'implémenter un des premiers circulateurs sans conversion de fréquence nette, sans pertes et sans ferrite. On montre que ce modèle de circuit se comporte bien comme un circulateur, avec une largeur de bande de l'ordre de 200 MHz et un niveau d'imperfections de -20 dB.

Reed-Solomon (RS) codes are non-binary, forward error-correcting codes. The RS code is flexible, in that a code can be shortened, extended, interleaved and concatenated. This flexibility has made the RS code an important design block in communication system design and today the RS code is used within a large number of applications from data storage systems to space telecommunications. Implementations of the coding and decoding strategies have until recently been limited to software due to their high complexity, however, with recent advances in IC fabrication technology it has become possible for RS codecs to be implemented in hardware. A hardware implementation has a smaller silicon requirement, and makes the technology a more applicable solution for real-time applications. However, the problem for a hardware RS codec design solution today is the acknowledged lack of codec design experts. The work outlined in this document addresses this problem through the use of Design Automation (DA). This thesis describes a solution that employs a non-proprietary, technology independent generic VHDL core. The core is a single, self-contained generic circuit description, written entirely in standard synthesizable VHDL and can therefore be used by any synthesis tool on any CAD system to produce a gate-level description for any available technology. The core developed implements a bit-serial RS codec, using a time domain algorithm for encoding, and a frequency domain algorithm for decoding. Only a limited number of code description parameters are required to be entered into the core to produce a completed design in seconds. The results presented in the thesis illustrate in detail that the VHDL core generates efficient circuit architecture in terms of silicon area which are within I% of hand-crafted designs. Comparison of synthesized results to hand crafted designs are presented for all circuit structures from the simplest multiplier up to entire encoders and decoders. Technology independence has been illustrated through the use of synthesis of the core to a traditional semi-custom gate array, LSI Logic LCA300k series, and to a popular Xilinx FPGA. The actual circuit topology, and therefore the route of the circuit critical paths, for the gate array implementation are almost identical to the handcrafted design., since the VHDL core was based on experience gained in creating those circuits. The only differences are attributable to minor differences in synthesis cell libraries that affect the circuit topology in a small way and of course the resulting maximum clock rate which wi11 always be technology-dependent. Obviously, for other architectures, for example FPGAs, the actual route of the critical paths will also be different, but the technology dependence of the critical path is beyond the scope of this thesis.

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