Dissertations / Theses on the topic 'Open systems theory'
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Sentís, Manuel Lorenzo. "Quantum theory of open systems." Zürich : ETH, Eidgenössische Technische Hochschule Zürich, Institut für Theoretische Physik, 2002. http://e-collection.ethbib.ethz.ch/show?type=dipl&nr=172.
Full textOssipov, Alexandre. "Open Mesoscopic Systems: beyond the Random Matrix Theory." Doctoral thesis, [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969598173.
Full textFong, Brendan. "The algebra of open and interconnected systems." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:79a23c8c-81a5-4cf1-a108-29ba7dfd8850.
Full textLevi, Elliott Kendrick. "Information transfer in open quantum systems." Thesis, University of St Andrews, 2017. http://hdl.handle.net/10023/16690.
Full textCollett, M. J. "Environmental correlations in the theory of open quantum systems." Thesis, University of Essex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378362.
Full textSchaumeier, Julia Gertrud. "Self-organising resource allocation in open systems : theory and experiments." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/14302.
Full textYu, Ting. "Approaches to open quantum systems : decoherence, localisation and all that." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/11479.
Full textOreshkov, Ognyan. "Topics in quantum information and the theory of open quantum systems." Doctoral thesis, University of Southern California, Los Angeles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/225666.
Full textMay, Meredith Augusta. "Applications of Queuing Theory for Open-Pit Truck/Shovel Haulage Systems." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/19218.
Full textMaster of Science
Giraldi, Filippo. "Decoherence, Master Equation for Open Quantum Systems, and the Subordination Theory." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4812/.
Full textGuidi, Hernan. "Open and closed-loop model identification and validation." Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-07032009-170311/.
Full textCarlsson, Jimmy. "A practical approach toward architectures for open computational systems." Thesis, Blekinge Tekniska Högskola, Institutionen för programvaruteknik och datavetenskap, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5821.
Full textMore material can be found on http://www.soclab.bth.se
Tempel, David Gabriel. "Time-Dependent Density Functional Theory for Open Quantum Systems and Quantum Computation." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10208.
Full textPhysics
Yurchenko, Aleksey. "Some problems in the theory of open dynamical systems and deterministic walks in random environments." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26549.
Full textCommittee Chair: Bunimovich, Leonid; Committee Member: Bakhtin, Yuri; Committee Member: Cvitanovic, Predrag; Committee Member: Houdre, Christian; Committee Member: Weiss, Howard. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Hales, Robert Frederick Michael. "Two Applications of Semiclassical Techniques to Open Systems : Transition State Theory and Microcavity Lasers." Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525457.
Full textDavies, I. "Optimal control of functional differential systems with application to transmission lines." Thesis, Coventry University, 2015. http://curve.coventry.ac.uk/open/items/11749285-3b9a-44cf-bc72-0d02c27141bc/1.
Full textNossal, Brigid Suzanne, and com au brigid@now. "Systems Psychodynamics and Consulting to Organisations in Australia." RMIT University. School of Health Sciences, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080513.144938.
Full textPinna, Lorenzo. "On the controllability of the quantum dynamics of closed and open systems." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX017/document.
Full textWe investigate the controllability of quantum systems in two differentsettings: the standard 'closed' setting, in which a quantum system is seen as isolated, the control problem is formulated on the Schroedinger equation; the open setting that describes a quantum system in interaction with a larger one, of which just qualitative parameters are known, by means of the Lindblad equation on states.In the context of closed systems we focus our attention to an interesting class ofmodels, namely the spin-boson models. The latter describe the interaction between a 2-level quantum system and finitely many distinguished modes of a bosonic field. We discuss two prototypical examples, the Rabi model and the Jaynes-Cummings model, which despite their age are still very popular in several fields of quantum physics. Notably, in the context of cavity Quantum Electro Dynamics (C-QED) they provide an approximate yet accurate description of the dynamics of a 2-level atom in a resonant microwave cavity, as in recent experiments of S. Haroche. We investigate the controllability properties of these models, analyzing two different types of control operators acting on the bosonic part, corresponding -in the application to cavity QED- to an external electric and magnetic field, respectively. We review some recent results and prove the approximate controllability of the Jaynes-Cummings model with these controls. This result is based on a spectral analysis exploiting the non-resonances of the spectrum. As far as the relation between the Rabi andthe Jaynes-Cummings Hamiltonians concerns, we treat the so called rotating waveapproximation in a rigorous framework. We formulate the problem as an adiabaticlimit in which the detuning frequency and the interaction strength parameter goes to zero, known as the weak-coupling regime. We prove that, under certain hypothesis on the ratio between the detuning and the coupling, the Jaynes-Cumming and the Rabi dynamics exhibit the same behaviour, more precisely the evolution operators they generate are close in norm.In the framework of open quantum systems we investigate the controllability ofthe Lindblad equation. We consider a control acting adiabatically on the internal part of the system, which we see as a degree of freedom that can be used to contrast the action of the environment. The adiabatic action of the control is chosen to produce a robust transition. We prove, in the prototype case of a two-level system, that the system approach a set of equilibrium points determined by the environment, i.e. the parameters that specify the Lindblad operator. On that set the system can be adiabatically steered choosing a suitable control. The analysis is based on the application of geometrical singular perturbation methods
Buchhold, Michael. "Thermalization and Out-of-Equilibrium Dynamics in Open Quantum Many-Body Systems." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-181786.
Full textBungart, Stefan. "Organisations as social systems : a study into the necessary systemic conditions for the occurrence of 'social resonance' to ecological issues in organisations." Thesis, Coventry University, 1999. http://curve.coventry.ac.uk/open/items/bed42cb2-9552-4631-bd99-9c109f4c061f/1.
Full textHarper, Sally Anne. "Urban open space : user perceptions of the Avis dam environment." Diss., University of Pretoria, 1998. http://hdl.handle.net/2263/23461.
Full textDissertation (MA)--University of Pretoria, 1998.
Psychology
unrestricted
Valyrakis, Manousos. "Initiation of Particle Movement in Turbulent Open Channel Flow." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/27289.
Full textPh. D.
Greening, Philip. "The influence of market structure, collaboration and price competition on supply network disruptions in open and closed markets." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8473.
Full textJack, Gillian. "Modelling the current state and potential use of knowledge management in higher education institutions." Thesis, Coventry University, 2004. http://curve.coventry.ac.uk/open/items/6fb700eb-b638-fa36-9a65-0e90e1f17b80/1.
Full textKönig, Christoph [Verfasser], Regina H. [Akademischer Betreuer] Mulder, and W. H. Adriaan [Akademischer Betreuer] Hofman. "Selection and allocation functions of teacher education systems - Development and test of a model based on Open Systems Theory / Christoph König. Betreuer: Regina H. Mulder ; W. H. Adriaan Hofman." Regensburg : Universitätsbibliothek Regensburg, 2014. http://d-nb.info/1059004860/34.
Full textMorton, Josh. "Legitimation through openness : managing organisational legitimacy through open strategy in a pluralistic context." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/28410.
Full textAlqithami, Saad. "Network Organization Paradigm." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/dissertations/1293.
Full textRowe, B. David. "Cultural Leadership and Peace: An Educational Response to Religious Violence." unrestricted, 2007. http://etd.gsu.edu/theses/available/etd-04302007-101357/.
Full textTitle from file title page. Philo A. Hutcheson, committee chair; Theophus Smith, Susan Talburt, Douglas R. Davis, committee members. Electronic text (355 p.) : digital, PDF file. Description based on contents viewed Nov. 1, 2007. Includes bibliographical references (p. 348-355).
Yuen-Zhou, Joel. "A Quantum Information Approach to Ultrafast Spectroscopy." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10317.
Full textFilho, José Inácio da Costa. "Quantum non-Markovianity induced by classical stochastic noise." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-10102017-155811/.
Full textUm dos objetivos principais da teoria de sistemas quânticos abertos é desenvolver métodos que ajudem a preservar as propriedades quânticas de um sistema interagindo com o ambiente. Um possível caminho para alcançar essa meta é usar reservatórios não-Markovianos, caracterizados por refluxos de informação e renascimento de certas propriedades quânticas. Esses reservatóris geralmente requerem o uso de técnicas avançadas de engenharia, o que pode tornar sua implementação impraticável. Nessa dissertação nós propomos uma técnica alternativa: a injeção de um ruído colorido clássico, o qual induz a desejada não-Markovianidade quântica. De modo a fazer isso, nós investigamos a dinâmica de um sistema quântico interagindo com o ambiente e sob a injeção de um ruído colorido clássico estocástico. Uma equação mestra local no tempo é derivada usando-se do formalismo da função de onda estocástica e de técnicas de cálculo funcional. Após isso, a não-Markovianidade da evolução é detectada através da medida de Andersson, Cresser, Hall e Li, a qual é baseada nos coeficientes da equação mestra na forma de Lindblad-like canônica. Finalmente, nós calculamos a medida para três diferentes ruídos coloridos e estudamos a relação entre o ambiente e o bombeio estocástico necessária para induzir não-Markovianidade quântica, assim como o balanço de energia do sistema.
Scopa, Stefano. "Non-equilibrium dynamics of driven low-dimensional quantum systems." Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0084/document.
Full textThis thesis analyzes some aspects regarding the dynamics of one-dimensional quantum systems which are driven out-of-equilibrium by the presence of time- dependent external fields. Among the possible kinds of driven systems, our focus is dedicated to the slow variation of a Hamiltonian’s parameter across a quantum phase transition and to the case of a time-periodic forcing. To begin with, we prepare the background and the tools needed in the following. This includes a brief introduction to quantum critical models (in particular to the xy spin chain and to the Bose-Hubbard model), the Kibble-Zurek mechanism and Floquet theory. Next, we consider the non-equilibrium dynamics of Tonks-Girardeau gases in time-dependent harmonic trap potentials. The analysis is made with different techniques: perturbative expansions, numerical exact diagonalization and exact methods based on the theory of Ermakov-Lewis dynamical invariants. The last part of the thesis deals instead with the non-equilibrium dynamics of markovian open quantum systems subject to time-periodic perturbations of the system parameters and of the environment. This has led to an exact formulation of Floquet theory for a Lindblad dynamics. Moreover, within the Lindblad-Floquet framework it is possible to have an exact characterization ofthe finite-time operation of quantum heat-engines
Kuhl, Ellen. "Theory and numerics of open system continuum thermodynamics spatial and material settings /." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971440492.
Full textCervati, Neto Alaor. "Teoria de controle ótimo em sistemas abertos." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/152661.
Full textRejected by Elza Mitiko Sato null (elzasato@ibilce.unesp.br), reason: Solicitamos que realize correções na submissão seguindo as orientações abaixo: 01) Primeira e segunda páginas antes da capa estão excedentes; 02) A ficha catalográfica deve ser na sequência da folha de rosto; 03) Na folha de aprovação deve constar a data (dia, mês e ano) da defesa 04) As folhas viii, 4, 42, 60, 66, 72, 74 e 78 estão em branco. Será encaminhado via e-mail o modelo das páginas pré-textuais para que você possa fazer as correções. Agradecemos a compreensão. on 2018-02-02T12:37:02Z (GMT)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A teoria de informação e computação quântica é uma área de pesquisa que vem crescendo de maneira acentuada nos últimos anos devido aos inúmeros avanços tecnológicos que a acompanham. Neste mestrado começamos nossos estudos nesta área de pesquisa onde nos introduzimos e aprofundamos em seus aspectos intrigantes e peculiares. Dada nossa formação inicial na área de ciências da computação, inicialmente nos dedicamos a entender os aspectos fundamentais da mecânica quântica, assim como da teoria de informação e computação quântica. Focamos principalmente nos sistemas quânticos abertos, visto que o maior obstáculo a ser superado para o desenvolvimento destes computadores é o efeito deletério do meio ambiente. A princípio, concentramos nossos estudos nos ditos processos não-Markovianos, que apresentam efeitos de memória. Aprendemos sobre as novas medidas de não-Markovianidade, principalmente as medidas baseadas na dinâmica do emaranhamento e na dinâmica da informação mútua. Conseguimos publicar nosso primeiro resultado, onde provamos a inequivalência destas duas medidas de não-Markovianidade. De fato, mostramos que tais medidas, em geral, podem discordar sobre o tipo de processo dissipativo, sendo que uma pode reconhecê-lo como Markoviano enquanto outra pode reconhecê-lo como não-Markoviano. Como mostramos, esta inequivalência está diretamente relacionada com o refluxo de informação do meio ambiente para o sistema, e como mensuramos tal informação nestas duas medidas distintas de não-Markovianidade. Finalmente, na fase final de nossos estudos, tivemos como objetivo encontrar um meio de otimizar o controle das operações lógicas. Especificamente, trabalhamos com um método numérico utilizado em sistemas fechados para otimizar sistemas abertos Markovianos. Observamos que a eficácia deste método depende do tipo e intensidade da interferência do ambiente e das condições iniciais do sistema, obtendo melhores resultados em casos específicos.
Quantum information theory and computation is a field of research that has been growing acutely in the past few years due to the many technological improvements it follows. In this masters’ course, we began our studies in this area of research where we were introduced and immersed in its intriguing and peculiar aspects. Given our initial formation in computer science, we initially dedicated ourselves to understanding the fundamentals of quantum mechanics, as well as of information theory and quantum computation. Our main focus were open quantum systems, since the greatest obstacle to the development of these computers is the harmful effect of the environment. At first, we concentrated our studies in the so called non-Markovian processes, that show memory effects. We learned about the new non-Markovianity measurements, mainly those based on the dynamics of entanglement and mutual information. We managed to publish our first result, where we proved the inequivalence of these two measurements of non-Markovianity. Indeed, we showed that such measurements, in general, can disagree about the dissipative process, so that one can regard it as Markovian and the other as non-Markovian. As we demonstrated, this inequivalence is directly related to the information back-flow from the environment to the system, and how this information is measured by each of the two distinct measurements. Finally, in the last stage of our studies, our goal was to find a way to optimize the control of the logical operations. Specifically, we worked with a numeric method used in closed systems to optimize Markovian open systems. We have observed that the effectiveness of this method depends on the type and intensity of the interference of the environment and of its initial conditions, attaining better results for specific cases.
Schirrmeister, Dirk. "Zur Theorie photoinduzierter Dynamik offener Molekularsysteme: Kontrolle von Dissipation durch ultrakurze Laser-Pulse." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 1998. http://dx.doi.org/10.18452/14380.
Full textabstract in PostScript This thesis investigates the influence of intense and ultrashort laser pulses on the photoinduced dynamics of open molecular systems. The excitation of a molecule by an optical ultrashort laser pulse induces transitions between different electronic states. This excitation process is accompanied by the dissipative processes of energy and vibrational relaxation. This excitation process is described within the method of the density matrix theory. Thereby, the derivation of the quantum master equation in the framework of the projection operator formalism demonstrates that the external fields are present in the reversible part of the equation of motion and also exert an indirect influence by acting on the dissipation superoperator which accounts for dissipation. In this thesis the field--dependency of the dissipation superoperator which is induced by the external fields is considered for the first time. By a representation of the quantum master equation in the Floquet picture, an interpretation of this field--dependent effect can be given: the frequency--dependent spectral density of the environmental modes which describe dissipation is determined at different field--dependent frequencies. Analytical investigations for the two level system demonstrate that the field dependence becomes relevant if the pulse length is comparable with the time scale on which the autocorrelation function of the environmental degrees of freedom decays.To investigate the influence on experimental quantities, a two--color pump--probe experiment for the laser dye molecule IR 125 is considered for which the spectrally and temporally resolved transmission on a femtosecond and picosecond time scale has been measured. Within the model of one effective vibrational mode the experimental data is fitted. The standard Redfield theory is used to provide a reference model. A high degree of concurrence between the theory and the results of the experiment is achieved. The exact treatment of internal conversion between the excited electronic states leads to a rise in transmission within one picosecond. It is necessary to solve the density matrix equations exactly because a comparative investigation with the nonlinear susceptibility of third order leads to a clear viation from the exact result. Starting from the reference case of field--independent dissipation, the field--dependency of the relaxation rates is determined and the influence on observables for example the relative transmission is investigated. The analytical results show that the field--dependent effect is strongest if the pulse length becomes smaller than the correlation time of the environmental modes and if the acting fields are sufficiently strong. Thereby, a control of dissipation becomes possible. An influence of the field--dependent effect on experimental observables is predicted.
Castro, Leonardo Andreta de. "Proteção de sistemas quânticos e o postulado da medida." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-20012017-090107/.
Full textThe processing of quantum information requires measurements, often preceded by unitary evolutions. A faithful description of a quantum computer should also take into account that the system interacts with an external environment - other than the observer - that removes it from its ideal evolution, causing errors. Here, we study the dynamics of quantum systems observed multiple times or continuously, while they interact with external environments. To do this, we employ a hybrid master equation, which allows us to model a continuous, Markovian interaction between the system and the measurement apparatus, while the environmental noise presents non-Markovian features. This study of the dynamics of the noisy continuous measurement reveals that the system better preserves its initial populations when the observable measured does not commute with the environmental noise operators. These results, already known for the simpler case of a memory qubit interacting with vacuum, are generalized for an initial temperature above zero and a qubit undergoing a quantum gate. The universality of these phenomena of preservation of the initial populations allows an analogy with the Quantum Zeno Effect. Keeping the same formalism, but adapting the environmental interaction to describe a decay, we verify that the quantum Zeno effect is observed for weak coupling with the environment. We also deal with how the knowledge about the preservation of the populations by the measurement helps in creating better ways to preserve the information in quantum codes. With the help of the weak measurement theory, we propose a simple experimental method to test the validity of models that describe a continuous measurement. With this study of the dynamics of a quantum measurement, we hope to help solve practical issues in quantum information processing, as well as provide greater insight into fundamental questions, such as the measurement postulate.
Muharish, Essa Yahya M. "PACKET FILTER APPROACH TO DETECT DENIAL OF SERVICE ATTACKS." CSUSB ScholarWorks, 2016. https://scholarworks.lib.csusb.edu/etd/342.
Full textKnoll, Carsten. "Regelungstheoretische Analyse- und Entwurfsansätze für unteraktuierte mechanische Systeme." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-209765.
Full textAnacker, Tony. "Incremental Scheme for Open-Shell Systems." Doctoral thesis, Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-197726.
Full textSeicean, Sinziana. "Exploring Sleep and the Hispanic Paradox in Mexico-born U.S. Adult Immigrants." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1278623005.
Full textBagci, Gokhan Baris Kobe Donald Holm. "The nonadditive generalization of Klimontovich's S-theorem for open systems and Boltzmann's orthodes." [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-9124.
Full textBagci, Gokhan Baris. "The Nonadditive Generalization of Klimontovich's S-Theorem for Open Systems and Boltzmann's Orthodes." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9124/.
Full textSvensson, Patrik, and Shahab Ataei. "En organisation för stor för sin egna kompetens : En kvalitativ forskningsstudie på polismyndigheten Värmlands internkommunikation." Thesis, Karlstads universitet, Avdelningen för medie- och kommunikationsvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-14577.
Full textThis bachelor thesis treats the subject of internal communication. We have chosen to carry through a research about the police department of Värmland's internal communication since they have big responsibility to preserve safety and security in society. The police department has these days greater demands regarding how to conduct dialogue and the level of communication within the organization to further the efficiency of police work. The main purpose of this bachelor thesis is to obtain insight about the internal communication functions and how it is presented from the managers as well as the employees perspective. In this thesis we are using relevant theories regarding organizational communication, internal communication, organization identity, organization culture and communication models. Our approach to answer the purpose of this thesis was to use two customized questions to enable us to get a overall view and a deeper insight of our chosen theoretical framework. “How do the managers perceive the internal communication in the police department of Värmland?” “How do the employees perceive the internal communication in the police department of Värmland?” In this study we used qualitative interviews and a qualitative focus group. The result we obtained, showed that, internal communication with the chosen managers and the employees had both positive and negative experiences. The police department of Värmland's internal communication has gone through a positive development according to the managers. According to the managers, the police department of Värmland has a healthy working environment that offers good possibilities for dialogue between management and employees, and also clear guidelines for how the internal communication has to be conducted. However, there is room for improvement, since some experience it to be hard to communicate information that filters wrongly and creates misunderstanding. But the employees gave us a completely different picture since the daily work characterized in injustice, faulty internal communication that creates confusion and difficulties to get an overview about who has what responsibilities in the organization.
Kästle, Oliver [Verfasser], Andreas [Akademischer Betreuer] Knorr, Alexander [Akademischer Betreuer] Carmele, Andreas [Gutachter] Knorr, and Peter [Gutachter] Rabl. "Open quantum system theory from an information perspective / Oliver Kästle ; Gutachter: Andreas Knorr, Peter Rabl ; Andreas Knorr, Alexander Carmele." Berlin : Technische Universität Berlin, 2021. http://d-nb.info/123814067X/34.
Full textGros, Jean-Baptiste. "Statistiques spatiales des cavités chaotiques ouvertes : applications aux cavités électromagnétiques." Thesis, Nice, 2014. http://www.theses.fr/2014NICE4150.
Full textMode-stirred reverberation chambers (RC) are used in the industry to test the immunity or the susceptibility of on-board electronic systems (plane, automobile, smartphone) towards the electromagnetic waves present in their environment. Mode-stirred RCs have to comply with a number of statistical criteria fixed by international standards. The chief criterion relies on a statistically uniform and isotropic field around the object under test. In order to improve and master the statistical properties of these systems for frequencies close to their lowest useable frequency, we suggest making them chaotic to take advantage of universal statistical properties of the resonances of chaotic cavities. We first show how to make chaotic RCs by simple modifications of a conventional RC and how to extend the predictions of the random matrix theory applied to the effective hamiltonien describing the open chaotic systems, to the case of vectorial fields. Then, we compare, by means of simulations and experiments, the distributions of intensity and the fluctuations of the maxima of the field in a conventional RC and in a chaotic RC close to the lowest useable frequency. This work illustrates that the universal spectral and spatial statistical properties of chaotic RCs allow to better comply with the criteria required by the international standards
Beyvers, Stephanie. "Selective excitation of adsorbate vibrations on dissipative surfaces." Phd thesis, Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2008/2551/.
Full textDie selektive Anregung von Molekülschwingungen mittels Infrarotlicht (IR) ist vorteilhaft, um die Wirkungsquerschnitte nachfolgender photochemischer oder photophysikalischer Prozesse zu steigern, welche durch Elektronenanregung mittels ultraviolettem (UV) bzw. sichtbarem (Vis) Licht ausgelöst werden. Für Adsorbatmoleküle auf Oberflächen wurden theoretische Vorhersagen getroffen, dass eine kombinierte (IR plus UV)-Strategie ("schwingungsvermittelte Chemie") die Ausbeute bei Photodesorption und anderen Photoreaktionen deutlich zu erhöhen vermag. Kürzlich wurde im Experiment gezeigt, dass eine rein IR-vermittelte Desorption möglich ist, welche über einen schwingungsangeregten Mechanismus erfolgt. Hierbei wurde molekularer Wasserstoff von einer Si(111)-Oberfläche desorbiert, an der atomarer Wasserstoff und atomares Deuterium gebunden waren. Eine thermische Anregung, die zum Bindungsbruch führt, konnte hierbei wegen der Isotopenselektivität ausgeschlossen werden. In der vorliegenden Arbeit wurde die selektive IR-Schwingungsanregung von Adsorbaten, die als multidimensionale Oszillatoren auf dissipativen Oberflächen behandelt wurden, mit Hilfe der Dichtematrixtheorie für offene Systeme simuliert. Nicht nur die potentialvermittelte Kopplung zwischen den einzelnen Moden ist ein Hindernis für selektive Anregung, sondern auch die Kopplung der Moden des Adsorbats ("Systems") an elektronische und phononische Freiheitsgrade des Substrats ("Bades"). Die Schwingungsrelaxation verläuft hierbei auf Zeitskalen, die von Millisekunden bis hin zu wenigen hundert Femtosekunden reichen, je nach Verfügbarkeit energetisch geeigneter Elektron-Loch-Paar-Anregungen bzw. Phononen (Gitterschwingungen) in der Oberfläche. Auf Metalloberflächen, bei denen die Schwingungrelaxation des Adsorbats zumeist von einem Elektronen-Loch-Paar-Mechanismus dominiert wird, sind die Schwingungslebensdauern normalerweise kürzer als auf Isolator- oder Halbleiteroberflächen und betragen einige Picosekunden, ebenso wie die Zeitskala der hier gewählten IR-Pulse. Weitere Faktoren, die die selektive Anregung behindern können sind die Harmonizität einer Mode und die geringe Dipolaktivität sogenannter "dunkler Moden", die eine Anregung mit moderat intensiven Feldern erschweren. Zusätzlich zu einfachen analytischen Pulsen wurden Felder mittels Optimaler Kontrolltheorie (OCT) erzeugt, um eine(n) Zielzustand/-mode maximal zu populieren. Komplexe OCT Pulse wurden mit Hilfe der Husimi-Transformation analysiert, welche das Kontrollfeld im Zeit- und Energieraum aufzulösen vermag. Die in dieser Arbeit untersuchten Adsorbat/Oberflächen-Systeme waren CO/Cu(100), H/Si(100) und 2H/Ru(0001), die sich als passende Modelle erwiesen, um oben genannte Faktoren zu untersuchen. Desweiteren wurden die Auswirkungen von Temperatur, reiner Dephasierung (elastische Streuprozesse), Dauer des IR-Pulses und Systemdimensionalit"at (Behandlung von bis zu vier Freiheitsgraden) studiert. Einzelne Schwingungsmoden konnten angeregt werden, in vielen Fällen sogar zustandsselektiv. Spezielle Prozesse wie die Anregung "heißer Banden", Desorption via alleiniger Schwingungsanregung und die Anregung "dunkler Moden" wurden simuliert. Schließlich wurde ein neuer OCT-Algorithmus in Dichtematrixdarstellung entwickelt, der es erlaubt, zeitabhängige Zieloperatoren einzuführen, um nicht nur Kontrolle über den Endzustand einer Anregung, sondern auch über den Anregungsmechanismus zu erlangen. Der Algorithmus basiert auf einer Kombination von globaler (iterativer) und lokaler (nicht-iterativer) optimaler Kontrollschemata in der Art, dass kurze, global kontrollierte Intervalle zeitlich lokal miteinander gekoppelt werden. Nach numerischen Tests wurde der Algorithmus erfolgreich angewandt, um eine Linearkombination aus zwei Zuständen zu stabilisieren, sowie um eine schrittweise "Leiteranregung" in einem harmonischen System zu forcieren, bei dem monochromatische, analytische Pulse mehrere Zustände zugleich anregen und somit einen Populationsverlust im angestrebten Zielzustand zur Folge haben.
El, Oussoul Abdellatif. "Etude et realisation d'un reseau local a insertion de registre : specification d'un protocole deterministe de niveau 1 et 2." Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF21061.
Full textWatanabe, Kota. "Non-adiabatic effects in quantum geometric pumping." Kyoto University, 2017. http://hdl.handle.net/2433/225998.
Full textWeilbach, Elizabeth Helena (Lizette). "An Institutional perspective on change management : a case study of an open source enterprise content management system (ECM) in the South African Public Sector." Thesis, University of Pretoria, 2014. http://hdl.handle.net/2263/39670.
Full textThesis (PhD-- University of Pretoria, 2014
Informatics
unrestricted
López, Delgado Daniel Antonio 1987. "Threshold theorem for a quantum memory in a correlated environment : Teorema do limiar para uma memória quântica em um ambiente correlacionado." [s.n.], 2016. http://repositorio.unicamp.br/jspui/handle/REPOSIP/321757.
Full textTese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: A criação de um computador quântico é um projeto que guia, ao mesmo tempo, avanços tecnológicos e um melhor entendimento das propriedades de sistemas quânticos e da Mecânica Quântica em geral. O teorema do limiar é derivado da teoria quântica de correção de erros e garante que, se o ruido estocástico que afeta os componentes de um computador quântico encontra-se abaixo de um valor limite, podemos operar esse computador quântico confiavelmente. Investigamos como esse teorema é modificado quando consideramos uma memória quântica (a qual usa o código de superfície para corrigir erros) acoplada a um ambiente correlacionado. O limiar de erros nesse caso é relacionado à transição de fase ordem-desordem de um sistema de spin equivalente
Abstract: The design of a quantum computer is a project which drives, at the same time, technological advancement and a better understanding of the properties of quantum systems and of Quantum Mechanics in general. The threshold theorem comes from quantum error correction theory and it guarantees that, if stochastic noise affecting the components of a quantum computer is below some threshold value, we can operate this quantum computer reliably. We investigate how this theorem is modified when we consider a quantum memory (which uses the surface code to correct errors) coupled to a correlated environment. The error threshold in this case is related the order-disorder phase transition of an equivalent spin system
Doutorado
Física
Doutor em Ciências
Boedecker, Geesche. "Resonance Fluorescence in a Photonic Crystal." Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2014/6959/.
Full textDie Arbeit befasst sich mit der Emission eines 2-Niveau-Atoms in einem photonischen Kristall mit einem treibenden Laser. Der photonische Kristall stellt für das Atom eine Umgebung dar, die seinen Zerfall verändert, insbesondere wenn die Übergangsfrequenz des Atoms nahe an der Bandkante ist. Es werden sowohl die Besetzungen als auch das Emissionsspektrum untersucht. Die Dynamik wird im Kontext offener Quantensysteme analysiert. Durch die vielfachen Reflexionen im photonischen Kristall hat das System ein endliches Gedächtnis, das die Markov-Näherung verhindert. Im Heisenberg-Bild stellen die Bewegungsgleichungen für die Systemvariablen eineunendliche Hierachie von Integro-Differentialgleichungen dar. Um ein geschlossenes System zu erhalten, sind Näherungen wie eine schwache Kopplung nötig. Zunächst wird ein einfacher photonischer Kristall betrachtet.: Der eindimensionale photonische Kristall, der aus wechselnden Lagen besteht. Die Blochmoden innerhalb und die Vakuummoden außerhalb des endlichen photonischen Kristalls sind durch eine Transformationsmatrix, die als Transfermatrix interpretiert werden kann, miteinander verbunden. Einfache Formeln für die Bandstruktur, Reflexion eines halb-unendlichen Kristalls, die lokale Zustandsdichte im absorbierenden Kristall werden gefunden; außerdem werden Defektmoden und negative Brechung diskutiert. Im quantenoptischen Teil der Arbeit werden zu Anfang drei Probleme diskutiert, die im Zusammenhang zum Problem der Resonanzfluoreszenz stehen und die analytisch berechnet werden können: Ein Dephasierungsmodell, das getriebenen Atom und Resonanzfluoreszenz im freien Raum. In der niedrigsten Ordnung der System-Bad-Kopplung werden die Erwartungswerte analytisch berechnet und die stationären Zustände werden für bestimmte Fälle diskutiert. Bei der Berechnung der Zweizeitkorrelationsfunktion und der Spektren taucht das zusätzliche Problem der Korrelationen zwischen den beiden Zeiten auf. Im Markov-Fall gilt das Quantenregressionstheorem. Im allgemeinen Fall kann stattdessen das Fluktuations-Dissipations-Theorem benutzt werden. Die Korrelationsfunktionen werden mit zwei verschiedenen Methoden berechnet. Innerhalb der gewählten Näherungen liefern beide Methoden dasselbe Resultat. Einige Plots zeigen die Abhängigkeit des Spektrums von den verschiedenen Parametern. Mehrere Beispiele für Squeezing-Spektren werden mit den verschiedenen Näherungen gezeigt. Eine Projektions-Operator-Methode wird benutzt, um zwei Arten einer Markov-Entwicklung zu implementieren, mit und ohne Faltungsintegral. Die niedrigste Ordnung ist identisch mit der niedrigsten Ordnung der System-Bad-Kopplung, wohingegen höhere Ordnungen andere Resultate ergeben.