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Zhou, Fei. "Coherence effects in mesoscopic systems /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/9787.
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Hansson, Annie. "Stark Spectroscopy, Lifetimes and Coherence Effects in Diatomic Molecular Systems." Doctoral thesis, Stockholm : Department of Physics, Stockholm University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-650.
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Kabir, Amin. "Phase coherent photorefractive effect in II-VI semiconductor quantum wells and its application for optical coherence imaging." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282315981.
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Seynat, Cedric. "Quantification of the effect of wind driven wheat motion on SAR interferometric coherence." Thesis, Cranfield University, 2000. http://hdl.handle.net/1826/834.
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This report quantifies the motion of wheat subject to wind and assesses the effect of this motion on the coherence obtained from Synthetic Aperture Radar (SAR) interferometry. Over vegetation, the loss of coherence due to the change in backscatter between two SAR images taken at a different time (temporal decorrelation) is related to the wind induced motion of vegetation elements. The research aims to provide simultaneous in situ measurements of crop motion and wind velocity at canopy height and to use these measurements in a coherence model to determine the quantitatively the parameters which infer temporal decorrelation. The potential of coherence for agricultural applications is assessed.
The three-dimensional motion of wheat is measured by a photogrammetry method
using two commercially available video cameras. Simultaneously, wind velocity at canopy height is measured by anemometers at a high sampling frequency. Wheat motion and wind velocity data were collected in a field local to Cranfield University in summer 2000. The CD attached to this report contains the wheat motion and wind velocity data. They show that the motion of wheat is correlated with the wind speed, and that wheat plants adjacent to each other move coherently.
The coherence model is based on a statistical approach, which represents the total backscatter from vegetation as the phasor addition of a fixed component and one or more components which are weather dependent. The relative contributions of the total backscatter are estimated with the RT2 backscatter intensity model. The motion measurements are used to define the variability of the phase of the weather dependent components in the model.
Outputs of the model show that a C-band SAR with an incidence angle of 23° (typical configuration of the ERS satellites) yields coherence values highly variable with the wind conditions at the time of the radar passes. The potential use of coherence for agricultural applications is limited by this variability, which infers the need for an accurate coherent backscatter model.
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DeBeus, Roger J. (Roger John). "The Effects of Music Training on Electroencephalographic Coherence of Preschool Children." Thesis, University of North Texas, 1999. https://digital.library.unt.edu/ark:/67531/metadc278071/.
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The purpose of this study was to examine the effects of music training on electroencephalographic (EEG) coherence of preschool children. EEG coherence is a measurement of brain wave activity that reflects anatomical and neurophysiological parameters and functional connectivity between areas of the brain. Participants were 4- to 6-year-old children divided into two groups: one received music training for 20 minutes twice a week for 10 weeks while the other group served as controls. Nineteen channels of EEG data were collected from each child pre- and post-training. Data were collected from three conditions: eyes-open resting, listening to music, and performing the Object Assembly subtest of the Weschler Preschool and Primary Scale of Intelligence - Revised (1989). The hypothesis was that the music training group would show increased EEG coherence as compared to controls. The EEG data was reduced into seven bandwidths and analyzed separately for each condition. Multiple ANCOVAs were used to factor out pre-test variability and to maximize connectivity changes between the two groups. The dependent measures were the post-QEEG electrode pairs and the covariates were the pre-QEEG electrode pairs. Results indicated the eyes-open and listening to music conditions showed more significant changes between the groups than the Object Assembly condition. Overall, each condition showed increased connectivity for the music training group versus controls. The eyes-open condition differentiated children with and without music training during a resting condition, and showed similar patterns as those identified by other researchers comparing musicians versus nonmusicians. The listening to music condition identified connections including a topographical pattern of auditory analysis, increased working memory activation, increased activity between musically sensitive areas, and increased interhemispheric activity. Findings with the Object Assembly condition were not as robust as expected. However, patterns of increased connectivity associated with visuospatial processing were found with the music training group.
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Lusk, Danielle Leigh. "The Effects of Seductive Details and Segmentation on Interest, Recall and Transfer in a Multimedia Learning Environment." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/26609.
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Multimedia learning theory, and the research that has supported it, is largely focused on the cognitive elements of learning. Although motivation has been mentioned as a factor in learning in a multimedia environment, motivation has not been measured as a distinctive variable in most studies. Specific attributes of multimedia, including seductive details and segmentation, have been hypothesized to increase interest; however, only studies examining these attributesâ effects on learning (measured by recall and transfer) have been conducted. The present study aimed to extend the examination of the use of seductive details and segmentation in multimedia learning by measuring interest in addition to recall and transfer.
The participants were 167 undergraduate students who were randomly assigned to four treatment groups involving a tutorial on the formation of lightning, which differed according to the multimedia attributes featured in the tutorial. Treatment groups included seductive details and segmentation (SD+S), seductive details and no segmentation (SD+NS), no seductive details and segmentation (NSD+S), and no seductive details and no segmentation (NSD+NS). Participants took an interest questionnaire before engaging with the tutorial and immediately following the tutorial. Tests of recall and transfer were used to measure learning after the tutorial. Two trained raters evaluated responses.
Data from the study were analyzed using Analysis of Variance (ANOVA) and correlation procedures. The results of the study revealed no significant differences among treatment groups in regards to interest, recall, or transfer. There was no significant relationship between interest and recall or interest and transfer. Although the results did not provide support for existing literature on seductive details and segmentation effects or reveal that these attributes increase interest, the implications of the findings present several valuable areas for future research.Ph. D.
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Curran, Andrew. "The Effect of Adding Relevant Music and Sound Effects to an Audio-Only Narration: A Three-Treatment Application of Mayer’s Coherence Principle." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1352397100.
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Bosch, Aguilera Manel. "Coherence and relaxation of an optically-driven bosonic quantum gas : experiments with ultracold ytterbium atoms." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS174.
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Dans ce travail de thèse, je présente une série d'études expérimentales réalisées avec des gaz d'ytterbium ultrafroids excités sur différentes transitions optiques. L'ytterbium appartient à la famille des atomes dits alcalino-terreux. Ces atomes possèdent une structure électronique riche, avec une transition d’horloge exempte d’émission spontanée et une transition étroite d'intercombinaison. Avec des expériences de spectroscopie sur la transition d'horloge dans des réseaux optiques profonds, je montre notre capacité à exciter cette transition de manière cohérente pendant de longues périodes. Ce contrôle est ensuite utilisé dans un premier temps en tant qu'outil pour mesurer les longueurs de diffusion des états impliqués dans la transition d'horloge et ensuite, pour préparer un petit système quantique ouvert, où la dissipation prend la forme de pertes à deux corps. En branchant ce couplage adiabatiquement, on observe une forte suppression de ces pertes, ce qui est interprété comme une signature de l'effet Zénon quantique. J'utilise finalement ce transfert cohérent pour étudier la dynamique de relaxation d'un condensat de Bose-Einstein. Enfin, je développe une étude sur un système ouvert avec des interactions fortes. Ici, on induit artificiellement de la dissipation sous la forme d'émission spontanée en utilisant la transition d'intercombinaison, et j'étudie comment la cohérence spatiale d'un superfluide dans un réseau optique est détruite. Ces expériences révèlent que la présence d'interactions fortes protège partiellement une cohérence résiduelle et entraîne un développement non-triviale de la décohérence, révélant ainsi l'émergence d'un canal de relaxation subdiffusifIn this thesis I report on a series of experimental studies performed with ultracold ytterbium gases driven in different optical transitions. Ytterbium belongs to the family of the so-called alkaline-earth-like atoms, which feature a rich electronic structure, with an optical clock transition free of spontaneous emission, and a narrow intercombination transition, making them very appealing for metrological and quantum simulation proposals. By performing spectroscopy on the clock transition, I prove on a first set of experiments in deep optical lattices our ability to drive this transition coherently for long times. This coherent control is then used for different studies. First, as tool to measure the scattering lengths of the states involved in the clock transition. Then, to prepare a small open quantum system, where dissipation arises in the form of two-body losses. By enabling the coupling adiabatically, we observe a strong suppression of these losses, which is interpreted as a signature of the quantum Zeno effect. I ultimately use the coherent driving to study the relaxation dynamics of a dissipative bulk Bose-Einstein condensate. Finally, I elaborate an investigation on a strongly-interacting open system. Dissipation is artificially induced in the form of spontaneous emission using the intercombination transition. Here, I study in which manner spontaneous emission destroys the spatial coherence of a superfluid in an optical lattice. These experiments reveal that the presence of strong interactions partially protects a residual amount of coherence and makes decoherence develop in a non-trivial manner, unveiling the emergence of a subdiffusive relaxation channel
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Grant, Desireé Chantelle. "The mediating effect of situational sense of coherence on the relationship between job insecurity and general health : a comparative study / Desirée [sic] Grant." Thesis, North-West University, 2005. http://hdl.handle.net/10394/2438.
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Dongol, Amit. "Carrier Dynamics and Application of the Phase Coherent Photorefractive Effect in ZnSe Quantum Wells." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1396453493.
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Griffiths, Christopher Alan. "A critical analysis of Antonovsky's sense of coherence theory in relation to mental health and mental disorder and the effect of a lifelong learning intervention on the sense of coherence of mental health service users." Thesis, Middlesex University, 2010. http://eprints.mdx.ac.uk/6286/.
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The theoretical focus of this thesis is Antonovsky's sense of coherence theory, the research paradigm is humanistic existential and the main area of investigation is mental health. The context of this thesis is the EU's Empowerment of Mental Illness Service Users: Lifelong Learning and Action (EMILIA) project which sought to increase the social inclusion and empowerment of mental health service users through providing formal learning and employment opportunities. Literature reviews were conducted on sense of coherence theory and on learning interventions for mental health service users. The sense of coherence literature review revealed a substantial level of research into the theory and its application. The investigation into learning interventions for mental health service users found that they can bring significant benefits. The thesis considered how Antonovsky's sense of coherence theory related to mental health and disorder and it found that the underlying theory has relevance in understanding coping with and the existence, development and treatment of mental disorder. The analysis indicated the possible mental health benefits of seeking to strengthen sense of coherence. The implications of the findings are discussed in relation to topics such as health care and recovery. A combined research methods approach was taken to the assessment of the EMILIA project. A quantitative study was conducted using the SOC-13 (Antonovsky, 1987) measure to assess whether participation in the EMILIA project strengthened sense of coherence. The results showed that involvement in EMILIA significantly increased sense of coherence. This result supports efforts to increase the social inclusion and empowerment of mental health service users through providing learning and employment opportunities. The results also revealed that there was a strong positive correlation between SF-36-v2 mental health related quality of life and SOC-13 at baseline, follow-up and change over time. These results are in line with the majority of previous studies conducted in this area. Qualitative thematic analysis was used to assess the mechanisms and processes that led to this result. This analysis helped demonstrate that the EMILIA project strengthened participants' ability to effectively respond to the needs and demands of their lives and it revealed insights into the mechanisms and application of SOC theory. In response to Antonovsky's call to study the sense of coherence concept using methods other than his orientation to life questionnaire, qualitative research methods were employed. This thesis investigated how sense of coherence theory applied when mapped onto descriptions by mental health service users of how they deal with problems that they face in their lives. The thematic analysis revealed that sense of coherence theory mapped effectively onto the interview transcripts. The analysis identified various factors that can be considered to be general resistance resources in the sense of coherence model. It also revealed distinctions between concrete and relationship orientated problem solving that led to an enhanced model of sense of coherence theory. This thesis proposes that SOC theory can be regarded as a theoretical framework for designing interventions for mental health service users that seek to enhance coping, adaptability, recovery, social inclusion, and empowerment. The results suggest that programmes similar to EMILIA style opportunities should be an integrated part of recovery focused provision. Overall commonalities in the findings of the two thesis studies provided new insights into the factors, mechanisms and processes involved in coping and adaption that are essential to and intertwined with SOC strength, mental health and recovery. Social capital was indentified as a key general resistance resource and the combined findings provide support for projects and interventions for mental health service users that seek to facilitate increased social capital.
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Olsson, Carin Therese Irene. "The effect of errors on the intelligibility of learner texts." Thesis, Karlstad University, Karlstad University, Karlstad University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-4111.
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Abstract: This paper is based on a qualitative investigation concerning the effect of errors on the intelligibility of learner texts and whether there are some errors that can be considered graver than others. The investigation was based on five student texts that were collected at an upper secondary school in the Swedish province of Värmland. The texts were sent to five native speaker evaluators in Britain and the United States of America. The errors represented were categorized as followed: substance, grammar, word choice, transfer errors and other errors.The results indicate that errors concerning substance, word choice, other errors and grammar were not considered grave. Concerning the grammatical errors, there were only a small number of cases that were considered grave. Therefore, the conclusion was drawn that grammatical errors do not affect the intelligibility of any of the five texts. However, the results from the investigation show that transfer errors, i.e. when the writer has transferred characteristics from the first language to the target language, were considered affecting the intelligibility to a larger extent than errors belonging to the other categories.
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CHENNAGOWNI, SURESH BABU. "STUDY OF THE EFFECT OF MASS DISTRIBUTION, PATH OF ENERGY AND DYNAMIC COUPLING ON COMBINED COHERENCE (A NON-LINEARITY DETECTION METHOD)." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1146177646.
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Nammontri, Orawan. "The effect of an intervention to enhance sense of coherence on oral health related quality of life : a cluster randomised controlled trial." Thesis, University of Sheffield, 2012. http://etheses.whiterose.ac.uk/2814/.
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Background: Psychological factors may influence oral health. One factor, sense of coherence (SOC) has been related to general and oral health, clinical status, oral health behaviours and oral health related quality of life (OHRQoL) in observational research with adults and children. Thus, improving SOC may be a way to improve OHRQoL. Aims of the study: To evaluate the effect of an intervention to enhance SOC on OHRQoL in children. Methods: Cluster randomised trial in twelve primary schools in Khonkaen, Thailand with 257 grade 5 students. Six schools were allocated randomly to the study and comparison groups respectively. Data included socio-demographic and clinical data. Self-report questionnaires assessed OHRQoL using the child perceptions questionnaire, CPQ11-14 and SOC with the 13-item SOC scale. Data were collected at three time points; at baseline, two weeks after the intervention and at 3 month follow up. Intervention: Seven 40-60 minute sessions over two months, focusing on child participation and empowerment. The first four sessions were classroom activities and included a mixture of didactic teaching, discussion, activities and games. The last three involved working on healthy school projects. The intervention was delivered by trained teachers who received an intensive one day course. Results: The two groups were similar for all variables at baseline. The intervention group had significant improvements in SOC and CPQ11-14 scores representing better OHRQoL at two weeks after the intervention and 3 month follow-up. SOC had a direct effect on symptoms and indirect effect on OHRQoL via symptoms. Conclusions: As well as providing experimental evidence that OHRQoL is determined by SOC, these data show that school-based interventions to enhance SOC may be a useful way to improve OHRQoL.
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Hyunh, Phuong-Anh. "Amélioration de la cohérence quantique dans le régime d'effet Hall quantique entier." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112021/document.
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Cette thèse est consacrée à l'amélioration de la cohérence dans le régime d'effet Hall quantique entier (EHQE) à facteur de remplissage ν=2, obtenu en appliquant un fort champ magnétique perpendiculairement au plan d'un gaz bidimensionnel d'électrons formé à l'interface d'une hétérostructure semiconductrice d'AlGaAs/GaAs. On obtient alors des conducteurs unidimensionnels chiraux (états de bord) permettant de réaliser l'équivalent électronique de l'interféromètre de Mach-Zehnder (IMZ), pour étudier la cohérence dans ce régime. L'observation inattendue d'une structure périodique en forme de lobes dans la visibilité des interférences en fonction de la tension appliquée en entrée suggère un rôle non négligeable des interactions.Dans un première partie nous expliquons l'émergence des états de bord dans le régime d'EHQE. Nous faisons ensuite l'état de l'art des connaissances concernant leur cohérence, puis nous présentons l'IMZ électronique du point de vue expérimental.Ensuite, nous détaillons les résultats expérimentaux, d'abord concernant la visibilité à tension finie: nos mesures confirment une prédiction théorique concernant un transition de phase quantique en fonction de la dilution de l'état de bord qui interfère ; nous ne voyons pas d'effet flagrant de la relaxation en énergie. Enfin, de précédents travaux(1) ayant identifié clairement l'état de bord voisin de celui qui interfère comme l'environnement limitant la cohérence du système, nous avons réalisé un nouveau type d'échantillon afin de diminuer le couplage à cet environnement de manière contrôlée. Nous avons ainsi augmenté la cohérence de moitié en accord quantitatif avec la théorie issue de précédents travaux(1).(1)P. Roulleau, F. Portier, P. Roche, A. Cavanna, G. Faini, U. Gennser, and D. Mailly. Noise Dephasing in Edge States of the Integer Quantum Hall Regime. Physical Review Letters, 101(18):186803–4, October 2008This PhD thesis is devoted to the engineering of quantum coherence in the integer quantum Hall effect regime (IQHE) at filling factor ν=2, obtained by applying a strong perpendicular magnetic field to a bidimensional electron gas formed at the interface of a GaAlAs/GaAs semiconducting heterostructure. Then unidimensional chiral conductors called edge states appear which can be used as electron beams to build the equivalent in condensed matter of a Mach-Zehnder interferometer (MZI) so as to study coherence in this regime. The unexpected periodic lobe structure of the visibility as function of the bias voltage suggests that interactions play an important role.In the first part, we explain how edge states emerge in the IQHE regime. We picture the state of the art on the edge states coherence. Then we present the MZI from the experimental point of view.Next we show our results, first concerning the visibility at finite bias: our measurements confirm a prediction about a quantum phase transition as function of the interfering edge state dilution. We don't see any significant manifestation of energy relaxation in the visibility. Finally, having identified the adjacent edge state as the noisy environment limitating coherence thanks to previous works, we have designed a new kind of sample to decrease the coupling of the system to this environment in a controlled manner. We thus decreased dephasing by half, in quantitative agreement with the theory developped previously in our group
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Nikolov, Plamen. "The effect of concurrent cognitive-visuomotor multitasking and task difficulty on dynamic functional connectivity in the brain." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/3185.
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This thesis investigated the effect of visuomotor and working memory 1) task difficulty and 2) multitasking on dynamic functional connectivity in the brain. Studies have only recently begun to investigate functional connectivity within the scope of concurrent dual task or varying task difficulty conditions (Cocchi, Zalesky, et al. 2011; Rietschel et al. 2012). A series of EEG recordings were conducted during execution of visuomotor or working memory tasks within a novel paradigm using BCI2VR custom MATLAB toolbox. Functional connectivity was correlated with task-related coherence (TRCoh) analysis between two task conditions involving either variation in task difficulty or concurrent execution during multitasking within the delta (0 – 4 Hz), theta (4 – 8 Hz), alpha (8 – 12 Hz), beta1 (12-16 Hz), beta2 (16 – 20 Hz) and beta3 (20 – 24 Hz) frequency bands. An increase in coherence was observed with increased cognitive load, during both increased task difficulty and multitasking, in all frequency bands except beta1 and beta2. This may suggest that the psychomotor efficiency hypothesis also applies to multitasking as well as task difficulty. Decreases in beta coherence were observed with increased performance error, indicating that interregional beta coherence may not follow the PEH trend. The increased coherence between brain regions in the alpha, delta and theta bands contributes to the growing volume of research on quantifying cognitive workload and may serve as a future basis on increasing multitasking efficiency during high stress environments. Further research recording multitasking effects on individuals over regular intervals during an extended period of time (months or years) will be required to better understand changes in functional connectivity within the brain.
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Grenier, Charles. "Optique quantique électronique." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2011. http://tel.archives-ouvertes.fr/tel-00617869.
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Les progrès des techniques de nanofabrication des dix dernières années ont permis la mise en place de protocoles visant à manipuler les charges uniques dans les nanostructures. Ces nouvelles techniques permettent d'envisager la réalisation d'expériences d'optique quantique avec des électrons. Cette thèse s'inscrit dans ce contexte. Le but de ce travail a été la construction d'un formalisme adapté à la description de telles expériences. Ce formalisme, construit en analogie avec la théorie de la cohérence quantique du champ électromagnétique de Glauber, souligne les similitudes et différences entre les photons se propageant dans le vide, et le transport électronique dans des conducteurs balistiques unidimensionnels. En particulier, il rend compte de la décohérence et de la relaxation en énergie des excitations électroniques en présence d'interactions. Un autre aspect de cette thèse a été la proposition de protocoles permettant de mesurer des quantités directement reliées aux propriétés de cohérence décrites par le formalisme de l'optique quantique électronique. En particulier, un protocole de tomographie quantique reposant sur l'effet Hanbury Brown et Twiss a été proposé pour reconstruire la cohérence à un corps d'une source monoélectronique. Ce protocole peut aussi être envisagé pour obtenir des informations sur les mécanismes de décohérence.
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Charlat, Pierre. "Transport et cohérence quantique dans les nanocircuits hybrides supraconducteur-métal." Phd thesis, Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10143.
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Nous avons etudie l'action a l'echelle mesoscopique de la presence d'un supraconducteur sur la conductance d'un circuit de metal normal. Apres une discussion de differentes theories concernant ce sujet, nous presentons des mesures a tres basse temperature (20 mk) mettant en evidence l'action non locale de la supraconductivite sur la conductance metallique. Nous montrons que la conductance du metal normal est alors fortement dependante de l'energie des electrons, l'energie caracteristique etant l'energie de thouless. Une experience d'interference effectuee dans la configuration aharonov-bohm met en evidence la portee de la coherence quantique de paires d'electrons dans le metal normal. Nous effectuons une comparaison detaillee avec la theorie des fonctions de green quasiclassiques. Cette comparaison met en evidence le role important joue par les parties exterieures de l'echantillon qui constituent les reservoirs. Nous presentons une technique originale de fabrication d'echantillons mesoscopiques hybrides de niobium et de cuivre. De plus, afin de pouvoir controler la formation des barrieres tunnel, nous avons developpe une vanne permettant de maitriser l'entree, dans un enceinte a ultra-vide, d'oxygene pur a partir de l'air. Nous decrivons un programme ecrit en langage c++, qui permet de calculer la conductance d'un circuit hybride quelconque compose de metal normal et de supraconducteur. Dans le cas ou deux supraconducteurs sont presents a des tensions differentes, l'effet josephson alternatif module la densite d'etats dans le metal normal. Nous presentons une experience, en cours de developpement, visant a mesurer les effets de ces variations de la densite d'etats sur le transport.
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Venturelli, Davide. "Mélange de canaux et transport de spin dans l'effet hall quantique entier." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00680044.
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Les états de bord sont des canaux de transport unidimensionnels qui se développent dans des puits quantiques en régime d'Effet Hall entier, avec de remarquables propriétés de chiralité et de cohérence quantique. Dans cette thèse nous présentons l'idée d'une manipulation de courants électroniques mettant en jeu le mélange de deux canaux de bord co-propageants, et nous discutons son impact potentiel pour l'interférométrie quantique et le transport de qubits de spin. Nous présentons les caractéristiques des états de bord et évaluons l'effet de potentiels locaux et non-adiabatiques, et de leur efficacité pour transférer la charge entre les deux canaux. Il est montré que des variations rapides du potentiel, d'amplitude plus petite que le gap de Landau, donnent lieu à un faible mélange, et nous identifions des stratégies expérimentales permettant d'atteindre un bon pourcentage de mélange. Nous développons des techniques de simulation numérique afin de modéliser de expériences qui mettent en jeu des canaux avec mélange, ainsi que des méthodes analytiques permettant de traiter les interactions coulombiennes entre états de bord, en vue de futures expériences d'interférométrie de spin.
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Anwar, Sarosh. "The Effect of the European External Action Service on the Coherence of the Common Foreign and Security Policy on the Vertical Dimension: A Comparative Analysis of the 2003 Iraq War and the 2011 Military Intervention in Libya." Thesis, Malmö högskola, Fakulteten för kultur och samhälle (KS), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-22932.
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How has the EEAS affected, if in any way, the coherence of the CFSP on the vertical dimension in security and defence matters? In this thesis I answer this research question in order to draw a conclusion on the affect of the EEAS on the cooperation and coordination of the MS with and within the CFSP in security and defence matters. Coherence within the EU’s foreign policy is an issue that its leaders have emphasized on developing for more than four decades. The introduction of the EEAS through the Lisbon Treaty in 2009 is perceived to enhance the cooperation and coordination of the MS with and within the CFSP, as well as coordinate the actions of the MS outside the boundaries of the EU. By conducting a multiple case study, in this thesis I compare how the most powerful MS: the UK, France, and Germany, interacted with and within the CFSP in the 2003 Iraq War, and the 2011 military intervention in Libya. Relatedly, a qualitative content analysis approach is applied in order to uncover all relevant information from the primary and secondary literature concerning the two cases. In contrast to most of the previous studies conducted on this topic, I combine and apply the theoretical perspectives of liberal institutionalism and social constructivism in order to explain and explore the phenomenon under investigation. Conclusively, this thesis suggests that the coherence of the CFSP on the vertical dimension in security and defence matters has not been affected in any way after the EEAS has been implemented in the CFSP. This is due to the inherent characteristic of the MS of always prioritizing their national interests, determined by their value-based normative ideas gained through social interaction, before a collective, effective, and coherent CFSP in defence and security terms.
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Davuluri, Subrahmanya Bhima Sankar. "Effects of Quantum Coherence and Interference." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc500094/.
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Quantum coherence and interference (QCI) is a phenomenon that takes place in all multi-level atomic systems interacting with multiple lasers. In this work QCI is used to create several interesting effects like lasing without inversion (LWI), controlling group velocity of light to extreme values, controlling the direction of propagation through non-linear phase matching condition and for controlling the correlations in field fluctuations. Controlling group velocity of light is very interesting because of many novel applications it can offer. One of the unsolved problems in this area is to achieve a slow and fast light which can be tuned continuously as a function of frequency. We describe a method for creation of tunable slow and fast light by controlling intensity of incident laser fields using QCI effects. Lasers are not new to the modern world but an extreme ultra-violet laser or a x-ray laser is definitely one of the most desirable technologies today. Using QCI, we describe a method to realize lasing at high frequencies by creating lasing without inversion. Role of QCI in creating correlations and anti-correlations, which are generated by vacuum fluctuations, in a three level lambda system coupled to two strong fields is discussed.
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Moazzezi, Mojtaba. "Quantum Coherence Effects Coupled via Plasmons." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1404550/.
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This thesis is an attempt at studying quantum coherence effects coupled via plasmons. After introducing the quantum coherence in atomic systems in Chapter 1, we utilize it in Chapter 2 to demonstrate a new technique of detection of motion of single atoms or irons inside an optical cavity. By taking into account the interaction of coherences with surface plasmonic waves excited in metal nanoparticles, we provide a theoretical model along with experimental data in Chapter 3 to describe the modification of Raman spectra near metal nanoparticles. We show in chapter 4 that starting from two emitters, coupled via a plasmonic field, the symmetry breaking occurs, making detectable the simultaneous existence of the fast super-radiance and the slow sub-radiance emission of dye fluorescence near a plasmonic surface. In Chapter 5, we study the photon statistics of a group of emitters coupled via plasmons and by the use of quantum regression theorem, we provide a theoretical model to fully investigate the dependence of photon bunching and anti-bunching effects to the interaction between atoms, fields and surrounding mediums.
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Paula, Arbouw. "Corporate brand coherency : examining the effects of the advertising congruence antecedent on consumer attitudes." Thesis, University of Canterbury. Marketing, management and entrepreneurship, 2014. http://hdl.handle.net/10092/9697.
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The overall aim of this thesis is to investigate the effects of coherence in the corporate branding process. Specifically, this thesis defines and develops the concept of corporate brand coherency (CBC) using four antecedents and four dimensions, and investigates the effects of incongruence based on the advertising antecedent by manipulating ad-brand congruence. Using the Elaboration Likelihood Model (ELM), the research tests whether two-sided messages aid the resolution of incongruence following central route processing and whether greater number of arguments could act as a peripheral cue. Accordingly, a conceptual model was developed to test the effects of ad-brand congruence, message sidedness and argument quantity on corporate credibility, attention and elaboration, attitude towards the ad and attitude towards the corporate brand.
To empirically test this model an online experiment (using a 3x2x2 between-subjects factorial design) was conducted, where subjects were exposed to a modified print advertisement for a grocery store. A total of 528 responses were collected from New Zealand Internet users. Two- and three-way ANCOVAs as well as path analysis was used to analyse the hypothesised relationships.
The results indicate support for CBC, as it was found that congruence led to positive evaluations and higher corporate credibility. Two-sided messages were not found to be effective in reducing the negative effect of incongruence. Instead, two-sided messages led to less favourable evaluations of incongruence. Regardless of the incongruence, the results show that two-sided messages did not lead to positive evaluations, while an increased number of arguments did lead to more favourable attitudes. Overall, the findings show the ELM is not applicable to explain consumers’ responses to incongruence, as incongruence was not found to affect message processing. Additionally, there was no support that message sidedness and argument quantity, respectively, acted as central and peripheral cues. Furthermore, findings indicate that incongruity in advertising can lead to positive evaluations when consumers have a negative prior brand attitude. The theoretical and managerial implications as well as directions for future research based on these findings are discussed.
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Kang, Dongyel. "PARTIAL COHERENCE AND ABERRATION EFFECTS ON SPECKLE CHARACTERISTICS." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/193613.
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It is known that a phase-perturbed object field from a fractal-like rough surface illuminated by a partially coherent beam generates speckle on the image plane. In this works, aberration effects on Gaussian speckle on the image plane in both perfectly and partially coherent systems are theoretically and experimentally investigated. Theory shows that the second order statistics of Gaussian laser speckle are independent of odd-functional aberrations, but they do affect Gaussian speckle contrast in a partially coherent system. Furthermore, it is theoretically derived that field statistics of Gaussian laser speckle generally become non-circular Gaussian due to aberrations, and an aberration effect is asymptotically ignorable for very weak or strong roughness. A brute force simulation method is introduced for non-Gaussian speckle in a partially coherent imaging system, where speckle irradiance is calculated from a quasi-monochromatic extended incoherent source. The source is modeled as a collection of independent point sources distributed on a regular grid. The partially coherent speckle pattern is calculated from the incoherent sum of coherent speckle patterns in the image plane generated from each point source. Speckle contrasts from a brute force model show good agreement with theoretical and experimental results. It is determined that non-Gaussian speckle contrast is strongly dependent on Hurst exponent of fractal rough surfaces using brute force simulations. The concept of a contributing object area at a fixed image point effectively explains the speckle contrast dependency. Measuring spherical aberrations using Gaussian laser speckle is discussed as one of applications and future works of the present study.
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Carty, Timothy. "Effects of injected atomic coherence on multiwave mixing." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184699.
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Discussion begins with a brief account of atomic level-pumping and reasons why atomic coherence is typically not considered in cw work on optical interactions. This dissertation is divided into four parts: semiclassical treatments of one-photon electric- dipole atom-field single-mode interactions and multimode interactions, and corresponding treatments for the two-photon interaction. We present the effects of injected atomic coherence on the polarization of the medium, the slowly varying envelope wave equation, the single- and multiwave mixing coefficients, and weak field propagation in a homogeneously broadened two-level medium. Spatial and temporal phase matching of the injected coherence to a field mode is crucial throughout, since the field may not be able to remain in phase with the induced and injected polarizations. One-photon injected coherence contributes directly to the polarization at the atomic resonance frequency. The perfectly phase-matched case leads to a linear superposition of an exponentially decaying field (Beer's law) and a constant field driven by the injected coherence. The interaction of an injected coherence with a detuned field produces frequency-symmetric sidebands about the pump field polarization. The sideband spacing equals the atom-field detuning. To probe the injected coherence we inject a weak resonant field. The resulting three-wave mixing leads to multiwave mixing coefficients that are unaffected to first-order in the weak sidemodes, but the injected coherence adds inhomogeneous terms to the coupled-mode equations. For both single- and multimode interactions the injected coherence does not affect the exponential growth/decay of the sidemodes, but it supports a weak field that may propagate if properly phase matched. For two-photon media the injected coherence requires at least one field interaction in order to produce a polarization, which then appears in the single- and multiwave mixing coefficients. The exponential growth/decay rate is modified by the injected coherence. For a centrally-tuned pump the injected coherence contributes the standard multiwave mixing terms as well as additional effects. Four-wave mixing is discussed as a means of relaxing the spatial phase matching constraint on the injected coherence.
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Yadav, Nirbhay N., and William S. Price. "Effects of polydispersity on PGSE NMR coherence features." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-193186.
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Real systems always contain some degree of polydispersity and yet the effects of this real and very important problem have not been studied in great detail in NMR diffusion experiments. The effects of polydispersity become even less clear when we are outside the short gradient pulse (SGP) limit (which we generally are). Here we investigate the effects of polydispersity, in the form of a Gaussian distribution of characteristic distances, on the coherence features of PGSE NMR experiments of a model system. Characteristic pore sizes were determined from the coherence features and compared to characteristic distances determined from Fourier transforms of the second derivative.
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Rohde, Hannah. "Coherence-driven effects in sentence and discourse processing." Diss., [La Jolla, Calif.] : University of California, San Diego, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3323581.
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Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed Sept. 9, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 202-209).
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Taras-Semchuk, John Paul Damian. "Coherence effects in mesoscopic normal and superconducting structures." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624879.
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Yadav, Nirbhay N., and William S. Price. "Effects of polydispersity on PGSE NMR coherence features." Diffusion fundamentals 6 (2007) 2, S. 1-12, 2007. https://ul.qucosa.de/id/qucosa%3A14176.
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Real systems always contain some degree of polydispersity and yet the effects of this real and very important problem have not been studied in great detail in NMR diffusion experiments. The effects of polydispersity become even less clear when we are outside the short gradient pulse (SGP) limit (which we generally are). Here we investigate the effects of polydispersity, in the form of a Gaussian distribution of characteristic distances, on the coherence features of PGSE NMR experiments of a model system. Characteristic pore sizes were determined from the coherence features and compared to characteristic distances determined from Fourier transforms of the second derivative.
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Zemirli, Saliha. "Etude sous haute pression de quelques fermions lourds : effets de cohérence et ordre magnétique." Grenoble 1, 1986. http://www.theses.fr/1986GRE10148.
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Mesures de conductivite sous haute pression a differentes temperatures pour ceal::(2), cecu::(2) et cecu::(6). Etudes par diffraction de neutrons, resistivite thermique et electrique, pouvoir thermoelectrique interpretees a l'aide de differents modeles
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Acton, J. M. "Quantum coherence effects in electronic, photonic and atomic structures." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595334.
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Light propagating through a disordered dielectric exhibits mesoscopic phenomena, such as coherent back scattering. In electronic systems, equivalent phenomena have been successfully described by the non-linear s-model. Starting from Maxwell’s equation in its full vector form, it is shown that disordered photonic systems, in two and three dimensions, can also be described by a non-linear s-model. The quasi classical approximation on which this theory is based is found to be valid in a window of frequencies. Numerical simulations of these systems are consistent with the s-model predictions. The mathematical equivalence between disordered photonic and electronic systems shows that the mechanisms for localization in the electronic and photonic band gaps are the same; numerical simulations to demonstrate this are presented. An investigation into the interplay of s-wave superconductivity and itinerant antiferromagnetism in disordered metals is presented. First, a s-model to describe this interplay is derived. It is used to obtain the phase diagram for the mean field phase transition between superconductivity and antiferromagnetism. The suppression of antiferromagnetism by disorder (which is analogous to the effect of magnetic disorder on superconductivity) culminates in a quantum critical point. The bilayer proximity effect is also investigated and the density of states inside an antiferromagnet coupled to a superconductor is obtained. Feshback resonance phenomena in ultracold Fermi gases are normally described by a Fermi-Bose model in which the Feshback molecule is treated as a point-like boson. We consider an alternative model of the 6Li system, in which a spin state is shared between the open and closed channels. In contrast to the Fermi-Bose model, a critical coupling in the open channel is required to induce a Feshback resonance, even at small detuning.
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Li, Jun. "Coherent multiple scattering effect in DIS." [Ames, Iowa : Iowa State University], 2007.
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García, Arellano Guadalupe. "Influence of the concentration and temperature on the spin relaxation time of donor-bound electrons immersed in a CdTe quantum well." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS109.
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Ce travail présente une étude de l'influence de la concentration de dopage, de la température et du champ magnétique longitudinal sur le temps de relaxation de spin des électrons liés aux donneurs immergés au milieu d'un puits quantique (PQ) de CdTe. En insérant les donneurs dans un PQ, les règles de sélection optique de la lumière polarisée circulairement sont purifiées, ce qui permet un meilleur degré d'orientation optique des spins des électrons que dans les cristaux 3D. En utilisant une technique de rotation Faraday photo-induite, nous mesurons d’abord le temps de relaxation de spin des électrons liés aux donneurs pour différentes concentrations de dopage à basse température dans le régime isolant. Ensuite, pour évaluer les mécanismes de relaxation de spin dans notre système, nous calculons l'énergie d'échange d'une paire d'électrons liés aux donneurs immergés au milieu d'un PQ infini, pour toute distance inter-donneur et différentes épaisseurs. En utilisant ce calcul, nous expliquons le comportement expérimental comme une interaction de deux mécanismes : l’interaction hyperfine et l’anisotrope d’échange. De plus, nous déterminons la constante spin-orbite dans CdTe αso = 0.079. Ensuite, nous présentons le développement d’une expérience pompe-sonde étendue permettant de mesurer les temps de relaxation de spin à l’échelle microseconde. Nous discutons brièvement des premiers résultats expérimentaux pour le temps de relaxation de spin longitudinal d'électrons liés aux donneurs immergés dans un PQ de CdTe avec différentes concentrations de dopage. Enfin, nous étudions l'évolution en température de la relaxation de spin de 10 à 80 K. On explique le comportement expérimental en invoquant l'échange de spin entre les électrons localisés et le spin d'électrons promus en états de conduction. Le spin des électrons localisés subit l’effet des interactions hyperfine et anisotrope, le mécanisme de D’yakonov-Perel’ régit la relaxation de spin des électrons de conductionThis work presents a study of the influence of doping concentration, temperature and longitudinal magnetic field on the spin relaxation time of donor-bound electrons immersed in the middle of a CdTe quantum well (QW). By inserting the donors in a QW, the optical selection rules for circularly polarized light are purified, allowing a higher degree of optical orientation of the electron spins than in 3D crystals. By using a photo-induced Faraday rotation technique, we first measure the spin relaxation time of donor-bound electrons for different doping concentrations at low temperature in the insulating regime. Then, in order to evaluate the spin relaxation mechanisms in our system, we calculate the exchange energy of a pair of donor-bound electrons immersed in the middle of an infinite QW, for any inter-donor distance and for different thicknesses. By using this calculation, we explain the experimental behavior as an interplay of two mechanisms: hyperfine and anisotropic exchange interactions. Moreover we determine the CdTe spin-orbit constant: αso = 0.079. Afterwards we present the development of an extended pump-probe experiment allowing to measure spin relaxation times at the microsecond scale. We briefly discuss the first experimental results for the longitudinal spin relaxation time of donor-bound electrons immersed in a CdTe QW with different doping concentrations. Finally, we investigate the temperature evolution of the spin relaxation in the range 10-80 K. The experimental behavior is explained by invoking spin exchange between electron spins localized on donors and the spin of electrons promoted to conduction states. The spin of localized electrons undergoes the effect of hyperfine and anisotropic exchange interactions, the D’yakonov-Perel’ mechanism governs the spin relaxation of the conduction electrons
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Rincón, Diana Constanza García. "Performane of partial directed coherence subject to volume consuction effects." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3154/tde-12072017-131157/.
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The strong relationship between cognitive processing and coherent behaviour and neurocognitive networks justifies the current huge interest in cortical functional connectivity modeling. This has fostered the development of connectivity estimators from the classical bivariate coherence concept to the notion of multivariate partial directed coherence (PDC) which provides information about temporal dependencies exposing cause and effect relationships. This work examines PDC performance for scalp EEG data whose research value has been subject to much debate in the light of the presence of volume conduction (VC) effects that often obscure the actual nature of cortical source dynamics. Through analytical considerations and simulations we show that even though (VC) can hinder accurate connectivity estimation, one can mitigate its effects by a judicious choice of scalp electrode configuration/ground reference. This observation allows settling the connectivity estimation adequacy debate in the presence of PDC.A forte relação que processamento cognitivo e comportamento coerente tem com redes neurocognitivas justifica o enorme interesse atual em modelamento de conectividade cortical. Este fato tem justificado o desenvolvimento de estimadores de conectividade desde a clássica coerência bivariada até a noção multivariada de coerência parcial direcionada (PDC) que exibe informação a cerca de dependências temporais que permitem expor relações de causa e efeito. O presente trabalho examina o desempenho da PDC no contexto de EEG de escalpo cujo valor em pesquisa sob os efeitos de condução de volume (VC) tem sido objeto de uma quantidade substancial de questionamentos na medida em esta obscurece a observação da dinâmica das fontes corticais. Por meio de considerações analíticas e simulações, mostramos que é possível mitigar os erros de estimação devidos à VC através da escolha judiciosa da configuração de eletrodos e da referência de terra. Esta observação permite resolver o conflito acerca da adequabilidade da inferência cortical baseada em EEG de escalpo.
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Soret, Ariane. "Forces induced by coherent effects." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX045/document.
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Dans cette thèse, nous étudions les effets cohérents associés à la propagation d’ondes dans les milieux diffusants, en particulier les ondes électromagnétiques.En milieux faiblement désordonnés, l'intensité lumineuse fluctue spatialement sur de grandes distances. Ce phénomène est le résultat d'effets cohérents mésoscopiques complexes, qui se produisent à une échelle microscopique. Nous montrons que ces fluctuations mésoscopiques cohérentes de la lumière induisent des forces de rayonnement d'un nouveau genre. L'amplitude de ces forces fluctuantes est déterminée par un paramètre unique et facilement réglable, la conductance adimensionnée, qui dépend à la fois de la géométrie et des propriétés de diffusion du milieu. Notre découverte devrait donc avoir des applications intéressantes, telles que de nouveaux capteurs pour la matière molle ou la biophysique.Du point de vue méthodologique, nous utilisons une approche à la Langevin pour décrire les fluctuations lumineuses cohérentes, où un bruit précisément calculé rend compte des effets cohérents mésoscopiques. Nous montrons comment inclure systématiquement les corrections cohérentes dans le terme de bruit, afin de reproduire les fluctuations d'intensité. Cette description permet de comprendre les fluctuations cohérentes comme résultant d’un flux lumineux hors équilibre, caractérisé par deux paramètres seulement, le coefficient de diffusion et la mobilité, qui sont par ailleurs liés par une relation d’Einstein. Un avantage évident de cette méthode est sa dépendance à deux paramètres seulement, ce qui fournit une description à la fois compacte et précise des riches effets cohérents sous-jacents. De plus, la correspondance que nous présentons entre la lumière cohérente et l'hydrodynamique hors d'équilibre est facilement généralisable à une large classe de problèmes d'ondes quantiques ou classiques.Pour les perspectives futures, cette connexion entre les effets cohérents mésoscopiques et les processus stochastiques hors équilibre devraient intéresser les communautés de la mésoscopie et de la mécanique statistique. Pour les premiers, le lien avec l'hydrodynamique hors équilibre fournit un nouvel éclairage sur la physique mésoscopique, ainsi que des outils utiles pour étudier les quantités jusqu'ici difficiles d'accès, telles que les fonctions de corrélation d'intensité d'ordres supérieurs. Pour les seconds, ces travaux devraient motiver une étude plus approfondie des processus indépendants du temps inspirés de la mésoscopieIn this work, we study coherent effects associated to wave propagation in scattering media, in particular electromagnetic waves.In weakly disordered media, light intensity fluctuates spatially over large distances. This phenomenon is the result of complex mesoscopic coherent effects, which occur at a microscopic scale. We show that these mesoscopic coherent fluctuations of light induce radiation forces of a new kind. The strength of these fluctuating forces is determined by a single and easily tunable parameter, the dimensionless conductance, which depends on both the geometry and the scattering properties of the medium. Our findings should therefore have interesting applications such as new sensors in soft condensed matter or biophysics.On the methodological viewpoint, we use a hydrodynamic Langevin approach to describe the coherent light fluctuations, where a properly tailored noise accounts for mesoscopic coherent effects. We show how to systematically include the coherent corrections in the noise term, in order to reproduce the intensity fluctuations. This description allows to understand coherent light fluctuations as resulting from a non equilibrium light flow, characterized by two parameters only, the diffusion coefficient and the mobility, otherwise related by an Einstein relation. A clear asset of this method is its dependence upon two parameters only, which provides a compact yet accurate description of the rich underlying coherent effects. Moreover, the mapping we present between coherent light and out of equilibrium hydrodynamics is easily generalizable to a large class of quantum or classical wave problems.For future perspectives, this connection between coherent effects in mesoscopics and non equilibrium stochastic processes should be of interest in both the mesoscopics and statistical mechanics communities. For the former, the mapping to non equilibrium hydrodynamics provides a new insight to mesoscopic physics as well as useful tools to study quantities so far difficult to access, such as higher orders intensity correlation functions. For the latter, this work should motivate further study of time independent processes inspired from mesoscopics
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Sala, Vera Giulia. "Coherence, dynamics and polarization properties of polariton condensates in single and coupled micropillars." Paris 6, 2013. http://www.theses.fr/2013PA066712.
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Microcavity polaritons are mixed light-matter quasiparticles arising from the strong coupling between quantum well excitons and photons confined in a Fabry-Perot microcavity. Their bosonic nature along with the strong interparticle interactions makes polaritons an excellent solid-state platform to study the nonlinear properties of bosonic condensates, with the advantage of being addressable using standard optical techniques. An important degree of freedom in the study of polaritons is the possibility to introduce a lateral confining potential. The growth and etching techniques developed at LPN allow obtaining low dimensional structures of different geometries, preserving high optical properties, opening the way to the study of polariton nonlinearities in at-will potential landscapes. During my PhD, my research has focused mostly on the experimental study of 0D structures, consisting of single micropillars and polaritonic molecules made of coupled micropillars. I studied the coherence properties of polariton condensates in single micropillars, by measuring the g2 function of the emission with a streak camera technique providing a time resolution of ~ 4 ps. I studied the Josephson physics in diatomic molecules made of two coupled micropillars, with particular attention to the nonlinear regimes. In particular the macroscopic self-trapping regime has been observed. Finally I studied a more complex molecule made of six coupled micropillars in a hexagonal shape, where an effective spin-orbit coupling for polaritons has been realized. These results highlight microcavity polaritons in micropillars as a platform where nonlinear effects can be studied, in combination with nontrivial topologiesLes polaritons de microcavité sont des particules mixtes lumière-matière issues du couplage fort entre les excitons dans un puits quantique et les photons confinés dans une microcavité Fabry-Pérot. Leur nature bosonique et les fortes nonlinéarités font des polaritons une excellente plateforme où l’on peut étudier les propriétés nonlinéaires des condensats des bosons, avec l’avantage de pouvoir les manipuler avec des techniques optiques. Un degré de liberté important est la possibilité d’introduire un potentiel latéral de confinement. Les techniques de croissance et de gravure développées au LPN permettent d’obtenir des géométries différentes qui préservent de hautes propriétés optiques. Cela ouvre la voie à l’étude des nonlinéarités dans les polaritons dans des potentiels sur mesure. Pendant mon doctorat, ma recherche a été focalisée sur l’étude expérimentale des structures 0D, en particulier des micropiliers simples et des molécules formées de piliers couplés. J’ai étudié les propriétés de cohérence des condensats de polaritons dans des piliers simples, en mesurant la fonction g2 de l’émission avec une streak camera possedant un temps de résolution de 4 ps. J’ai étudié la physique de Josephson dans des molécules polaritoniques faites de deux piliers couplés, avec une attention particulière au régime nonlinéaire. En particulier le régime de self-trapping a été observé. J’ai étudié une molécule plus complexe composée de six piliers couplés dans une structure hexagonale, où un couplage spin-orbite effectif a été réalisé. Ces résultats etablissent les polaritons de microcavité comme une plateforme où les effets nonlinéaires peuvent être étudiés en combinaison avec des topologies non triviales
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Tenorio-Pearl, Jaime Oscar. "Coherent control of a trapped electron in a disordered dielectric." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708428.
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Shen, Jianqi. "Quantum Coherence and Quantum-Vacuum Effects in Some Artificial Electromagnetic Media." Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10074.
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The author of this thesis concentrates his attention on quantum optical properties of some artificial electromagnetic media, such as quantum coherent atomic vapors (various multilevel electromagnetically induced transparency vapors) and negative refractive index materials, and suggests some possible ways to manipulate wave propagations inside the artificial electromagnetic materials based on quantum coherence and quantum vacuum effects. In Chapters 1 and 2, the author reviews the previous papers on quantum coherence as well as the relevant work such as electromagnetically induced transparency (EIT), atomic population trapping and their various applications. The basic concepts of quantum coherence (atomic phase coherence, quantum interferences within atomic energy levels) and quantum vacuum are introduced, and the theoretical formulations for treating wave propagations in quantum coherent media are presented. In Chapter 3, the author considers three topics on the manipulation of light propagations via quantum coherence and quantum interferences: i) the evolutional optical behaviors (turn-on dynamics) of a four-level N-configuration atomic system is studied and the tunable optical behavior that depends on the intensity ratio of the signal field to the control field is considered. Some typical photonic logic gates (e.g. NOT and NOR gates) are designed based on the tunable four-level optical responses of the N-configuration atomic system; ii) the destructive and constructive quantum interferences between two control transitions (driven by the control fields) in a tripod-type four-level system is suggested. The double-control quantum interferences can be utilized to realize some photonic devices such as the logic-gate devices, e.g., NOT, OR, NOR and EXNOR gates; iii) some new quantum coherent schemes (using EIT and dressed-state mixed-parity transitions) for realizing negative refractive indices are proposed. The most remarkable characteristic (and advantage) of the present scenarios is such that the isotropic left-handed media (with microscopic structure units at the atomic level) in the optical frequency band can be achieved. Quantum vacuum (the ground state of quantized fields) can exhibit many interesting effects. In Chapter 4, we investigate two quantum-vacuum effects in artificial materials: i) the anisotropic distribution of quantum-vacuum momentum density in a moving electromagnetic medium; ii) the angular momentum transfer between quantum vacuum and anisotropic medium. Such quantum-vacuum macroscopic mechanical effects could be detected by current technology, e.g., the so-called fiber optical sensor that can measure motion with nanoscale sensitivity. We expect that these vacuum effects could be utilized to develop sensitive sensor techniques or to design new quantum optical and photonic devices.In Chapter 5, the author suggests some interesting effects due to the combination of quantum coherence and quantum vacuum, i.e., the quantum coherent effects, in which the quantum-vacuum fluctuation field is involved. Two topics are addressed: i) spontaneous emission inhibition due to quantum interference in a three-level system; ii) quantum light-induced guiding potentials for coherent manipulation of atomic matter waves (containing multilevel atoms). These quantum guiding potentials could be utilized to cool and trap atoms, and may be used for the development of new techniques of atom fibers and atom chips, where the coherent manipulation of atomic matter waves is needed.In Chapter 6, we conclude this thesis with some remarks, briefly discuss new work that deserves further consideration in the future, and present a guide to the previously published papers by us.QC 20100810
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De, Echaniz SebastiaÌn R. "Coherence effects in three and four level laser cooled rubidium systems." Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250490.
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Carbone, Jonathan N. "It Must Have Been Him: Coherence Effects within the Legal System." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2204.
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The present series of studies examine how jurors and public defenders evaluate different pieces of evidence and integrate them into a coherent conclusion within the context of a criminal case. Previous research has shown that in situations where both sides of the case are compelling, decision-makers nevertheless come to highly confident and polarized decisions, called coherence shifts (Simon, 2004). The present research sought to expand on coherence effects, improve upon the methodology of previous studies, and explore potential moderators of coherence. In Study 1, mock jurors (n = 306) read about a criminal case and evaluated multiple pieces of evidence at various points throughout the case. Results indicated that participants exhibited pronounced coherence shifts (i.e., their evaluations of the various pieces of evidence (a) became more consistent as the case progressed, and (b) were evaluated in line with their initial leanings) using an improved methodology that randomized evidence order and evidence valence. Furthermore, participants’ interim leanings of guilt or innocence biased their subsequent evaluations of ambiguous evidence. The direction and magnitude of participants’ coherence shifts were predicted by their pretrial dispositions towards prosecution and defense. Participants lacked awareness of how their perceptions of the evidence have shifted. Coherence shifts were not, however, moderated by asking mock jurors to justify their decisions, or by asking mock jurors to play devil’s advocate while considering each piece of evidence, underscoring the pervasiveness of this cognitive bias. Study 2 examined whether actual public defenders experience coherence shifts and how those shifts relate to the plea bargaining process; however, no coherence shifts were observed. Study 3 examined whether the timing of the defense’s presentation of their case could reduce coherence effects; results indicated that reading about the defense’s case immediately after the prosecution’s case (c.f. following a delay) marginally (p = .09) reduced coherence effects among jurors who acquitted the defendant, suggesting one potential strategy to mitigate this bias.
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Seviour, Robert Francis. "Quasiclassical studies of phase-coherent transport in superconducting nanostructures." Thesis, Lancaster University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310577.
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Ye, S. "Coherent effects in dispersive quantum dynamics." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1353701/.
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This doctoral dissertation is concerned with the study of quantum dynamics where finite dimensional systems (typically two-level `qubits') interact with or through a set of bosonic modes, in various different configurations. Our main focus is on identifying and investigating signatures of quantum coherence emerging between the qubits in such dynamical situations. We first present a toy model where two qubits are encoded in the single-excitation subspace of the global system and study the average fidelity of a controlled-Z (CZ) quantum gate mediated by the bosonic modes. Next, we turn to analytically intractable spin-boson like models, by adopting the Multi-configurational Ehrenfest (MCE) method. We apply MCE to the study of the Choi fidelity of a CZ gate between two distant qubits, mediated by sets of bosonic modes (including sets which represent discretization of bath's continua) under different coupling Hamiltonians. The testing of the MCE method is then pushed further by a comparative analysis with full variational approaches and adiabatic path integral techniques in a case of super-Ohmic spin-boson model. Finally, we determine a general error bound applicable to most approximated treatments of unitary quantum evolutions, and suitable to compare MCE with other numerical techniques for the study of spin-boson dynamics.
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Mitryukovskiy, Sergey. "Coherent Secondary Radiation from Femtosecond Laser Filaments." Palaiseau, Ecole polytechnique, 2014. https://tel.archives-ouvertes.fr/tel-01091553/document.
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La filamentation laser est un phénomène optique non-linéaire qui apparaît spontanément au cours de la propagation d’une impulsion laser ultracourte intense dans un milieu transparent, quand sa puissance crête dépasse une valeur critique (quelques Gigawatts dans l’air). A un tel niveau d’intensité le faisceau a tendance à se contracter en raison de l’effet Kerr optique jusqu’à ce que l’intensité devienne suffisamment élevée pour ioniser le milieu, donnant naissance à un plasma de défocalisation. Par la suite, une compétition dynamique entre ces deux effets a lieu, produisant un canal de plasma mince et faiblement ionisé dans le sillage de l’impulsion. Depuis sa découverte en 1995, la filamentation laser femtoseconde dans l’air a suscité un intérêt considérable en raison de la physique riche impliquée dans ce processus et de la large gamme d’applications potentielles (détection à distance, conversion de fréquences optiques, contrôle atmosphérique par laser, génération d’ondes Térahertz, etc. ). Cette thèse est consacrée principalement à l’étude des rayonnements secondaires cohérents émis lors de la filamentation femtoseconde dans les gaz. Tout d’abord, je me suis intéressé à la luminescence ultraviolet des filaments de plasma, qui est associée à les transitions de l’azote moléculaire neutre et ionique dans un état excité. J’ai démontré que cette luminescence dépend fortement de l’état de polarisation des impulsions laser incidentes. J’ai ensuite décrit et interprété pour la première fois l’apparition d’un gain optique important observé vers l’arrière de la colonne de plasma dans l’azote. Ce gain apparait lorsque les impulsions laser femtoseconde à 800 nm sont polarisées circulairement et à pression atmosphérique. Cet effet constitue une étape importante vers la réalisation d’un “laser dans le ciel”. La dernière partie de la thèse, porte sur la génération du rayonnement Térahertz par plusieurs filaments laser femtoseconde. Par la synthèse cohérente du rayonnement Térahertz d’un réseau de filaments, j’ai ainsi démontré la possibilité d’accroitre l’intensité Térahertz et de contrôler la directivité de ce rayonnement par l’organisation de filaments multiplesLaser filamentation is a nonlinear optical phenomenon which appears spontaneously during the propagation of an intense ultrashort laser pulse in a transparent medium, when the pulse peak power exceeds a critical value (several Gigawatts in air). At such an intensity level the beam tends to collapse due to the optical Kerr self-focusing effect until the intensity is high enough to ionize the medium, giving rise to a defocusing plasma. Thereafter, a dynamic competition between these two effects takes place, leaving a thin and weakly ionized plasma channel in the wake of the pulse. Following its discovery in 1995, femtosecond laser filamentation in air has attracted considerable interest because of the rich physics involved in the process and the wide range of potential applications (remote sensing, light frequency conversion, laser-based weather control, Terahertz generation, etc. ). This thesis is devoted to the study of the coherent secondary emission from femtosecond laser filaments in gases. First, the ultraviolet luminescence of plasma filaments, corresponding to transitions of excited neutral and ionic molecular Nitrogen, is studied. I demonstrate that this luminescence depends strongly on the polarization state of the incident laser pulses. I further report and interpret for the first time a strong optical gain in the backward direction from plasma filaments created by circularly polarized 800 nm femtosecond laser pulses at normal pressure. This effect is a significant step towards the realization of a “laser in the sky”. In the last part of the thesis, I discuss the Terahertz generation from multiple femtosecond laser filaments in air. The coherent synthesis of the Terahertz radiation from an array of filaments is demonstrated, showing the capability for energy scaling up and directionality control of the Terahertz emission
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Dobrev, Georgi. "Laser spectroscopy for coherent manipulation and state-specific probing of atoms and molecules." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1083/document.
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Cette thèse décrit le travail expérimental sur différentes techniques visant l'obtention du contrôle de l'état quantique d'atomes et de molécules, pour application dans l'informatique quantique, la métrologie et l'astrophysique. Le contrôle cohérent exige des conditions précises de fonctionnement d'un système où la décohérence est minimisée. La construction d'une machine à jet atomique de calcium est présentée comme l'élément de base d'expériences où des schémas d'excitation laser choisis permettront de préparer de façon robuste un état quantique au moyen d'impulsions composites. La deuxième section décrit ma contribution pour améliorer la stabilité de fréquence relative de l'horloge à fontaine de cesium CSF2, à l'institut allemand de métrologie. Un piège magnéto-optique modifié produit un faisceau d'atomes de césium lents. Ils sont préparés dans un état noir spécifique puis sont efficacement transférés à la mélasse optique de la fontaine. L'augmentation du nombre d'atomes participant ainsi au cycle d'horloge améliore sa stabilité d'un facteur 6. La troisième section concerne les spectres de molécules NiH et FeH. Plusieurs sources pour leur production en laboratoire ont été développées et testées. Une expérience d'absorption laser différentielle et une technique de spectroscopie intra-cavité sont appliquées aux molécules faiblement absorbantes NiH, afin d'obtenir leurs coefficients d'absorption dans le rouge. La réponse Zeeman de la molécule FeH (une sonde du champ magnétique des étoiles froides) dans le proche infrarouge est étudiée par spectroscopie laser de précision afin d'établir des facteurs Landé pour 33 niveaux rovibrationnelles de l'état électronique F 4?This thesis describes experimental work on different techniques aiming to achieve control of the quantum state of atoms and molecules, envisaging applications in quantum computing, metrology and astrophysics.Successful coherent control requires careful design of operating conditions for a system where decoherence is minimized. The construction of a calcium atomic beam is presented as a necessary element in experiments with laser excitation schemes chosen to provide high-fidelity preparation of a quantum satate by means of composite pulses. The second section describes my contribution to the improvement of the relative frequency stability of the Cs fountain clock CSF2 at the German institute of metrology. A modified magneto-optical trap is employed to form a beam of slow cesium atoms. They are prepared in a specific dark state and subsequently are efficiently transferred to the optical molasses of the fountain. Increasing number of atoms participating in the clock cycle in this way improves the stability of the clock by a factor of 6.The third section is concerned with spectra of metal hydride molecules NiH and FeH. Several sources for production of these molecules in laboratories were developed and tested. A differential laser absorption experiment and a cavity-enhanced spectroscopy technique are applied on the w??kly absorbing NiH molecules, to obtain absorption coefficients for the red bands of NiH. The Zeeman response of the FeH molecule (a probe for magnetic fields in cool stars) in the near-IR is investigated by precision laser spectroscopy establishing Landé factors for 33 rovibrational levels of the F 4? electronic state
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Djokic, Vladimir [Verfasser]. "Coherence effects and spectroscopy in laser driven dense atomic vapour / Vladimir Djokic." Bonn : Universitäts- und Landesbibliothek Bonn, 2016. http://d-nb.info/1096329883/34.
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Russell, Christopher David. "Study of interference effects and signal processing techniques in optical coherence tomography." Thesis, University of Liverpool, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406628.
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Đokić, V. [Verfasser]. "Coherence effects and spectroscopy in laser driven dense atomic vapour / Vladimir Djokic." Bonn : Universitäts- und Landesbibliothek Bonn, 2016. http://nbn-resolving.de/urn:nbn:de:hbz:5n-42755.
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Schwanzer, Miroslav. "Studium vlivu akustických podnětů na člověka." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-374608.
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The thesis deals with EEG signals, their description, methods of quantitative analysis and the processes in time-frequency domains, or power spectrums. The relationsheep between brain electrical activity and acustic stimuli (Mozart´s “Sonata K448”) was studied using EEG analysis in relation to sound impulses from replayed extracts of. The proposed experiment protocol included recording of EEG of volunteers. In order to visualize and analyze the data, the software with the graphic user interface was created, which enables topological mapping of brain activity and its vizualization in the time-frequency domain.
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Sequeira, António D. "Effect of coherency strains on the decomposition of Ni-Al-Mo alloys /." [S.l.] : [s.n.], 1994. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10440.
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Pellan, Yves. "Etude de la metastabilite de la transition supraconductrice de films divises d'indium sous champ magnetique parallele et perpendiculaire." Rennes, INSA, 1987. http://www.theses.fr/1987ISAR0007.
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Mesures systematiques des champs de surchauffe et de retard a la condensation et du champ critique thermodynamique du film en fonction de l'epaisseur, de la temperature et de l'orientation du champ magnetique, sur deux series de films deposes sur des substrats a 295k et 77k. Determination de la profondeur de penetration, de la longueur de coherence et du parametre de ginzburg-landau de l'indium supraconducteur pur