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Tengner, Maria. "Photonic Qubits for Quantum Communication : Exploiting photon-pair correlations; from theory to applications." Doctoral thesis, KTH, Mikroelektronik och tillämpad fysik, MAP, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4798.
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For any communication, the conveyed information must be carried by some physical system. If this system is a quantum system rather than a classical one, its behavior will be governed by the laws of quantum mechanics. Hence, the properties of quantum mechanics, such as superpositions and entanglement, are accessible, opening up new possibilities for transferring information. The exploration of these possibilities constitutes the field of quantum communication. The key ingredient in quantum communication is the qubit, a bit that can be in any superposition of 0 and 1, and that is carried by a quantum state. One possible physical realization of these quantum states is to use single photons. Hence, to explore the possibilities of optical quantum communication, photonic quantum states must be generated, transmitted, characterized, and detected with high precision. This thesis begins with the first of these steps: the implementation of single-photon sources generating photonic qubits. The sources are based on photon-pair generation in nonlinear crystals, and designed to be compatible with fiber optical communication systems. To ensure such a compatibility and to create a high-quality source, a theoretical analysis is made, optimizing the coupling of the photons into optical fibers. Based on the theoretical analysis, a heralded single-photon source and a two-crystal source of entangled photons-pairs are experimentally implemented. The source of entangled photons is further developed into a compact source with a narrow bandwidth compatible with standard telecommunication wavelength-division multiplexers, and even further developed to a more stable one-crystal source. The sources are to be used for quantum communication in general and quantum cryptography in particular. Specifically, a heralded single-photon source is implemented and then used for a full test of a decoy-state quantum cryptography protocol.QC 20100914
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Courtney, Peter R. "Correlation techniques for application in photon correlation spectroscopy." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237235.
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Danley, Tyler W. "Photon-Related Elliptic Azimuthal Asymmetry and Photon-Hadron Correlations with an Isolation Cut in Au+Au Collisions at v(s_NN )= 200 GeV at RHIC-PHENIX." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1542201804266935.
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Gardezi, Akber Abid. "Pattern recognition employing spatially variant unconstrained correlation filters." Thesis, University of Sussex, 2013. http://sro.sussex.ac.uk/id/eprint/47055/.
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A spatial domain Optimal Trade-off Maximum Average Correlation Height (SPOT-MACH) filter is proposed in this thesis. The proposed technique uses a pre-defined fixed size kernel rather than using estimation techniques. The spatial domain implementation of OT-MACH offers the advantage that it does not have shift invariance imposed on it as the kernel can be modified depending upon its position within the input image. This allows normalization of the kernel and allows inclusion of a space domain non-linearity to improve performance. The proposed SPOT-MACH filter can be used to maximize the height of the correlation peak in the presence of distortions of the training object and provide resistance to background clutter. One of the major characteristics of the SPOT-MACH filter is that it can be tuned to maximize the height and sharpness of the correlation peak by using trade-offs between distortion tolerance, peak sharpness and the ability to suppress clutter noise. A number of non-parametric local regression techniques offer a simplified approach to pattern recognition problems which employ linear filtering using low pass filters designed using moving window local approximations. In most of these cases the algorithms search for a region of interest near the point of estimation for various prevailing conditions which fit the required criteria. These estimates are calculated for a defined window size which is determined as being the largest area within which the estimators do not widely vary from the criteria. The only drawback in this approach is that the window size is directly proportional to the required computational resources and would adversely affect the performance of the system if the moving window size is not proportionate to the resources. The proposed filter employs an optimization technique using low-pass filtering to highlight the potential region of interests in the image and then restricts the movement of the kernel to these regions to allow target identification and to use less computational resources. Also another optimization technique is also proposed which is based on an entropy filter which measures the degree of randomness between two changing scenes and would return the area where change has occurred i.e. the target object might be present. This approach gives a more accurate region of interest than the low-pass filtering approach. Apart from the software based optimization approaches two hardware based enhancement techniques have also been proposed in this thesis. One of the approaches employs Field Programmable Gate Array (FPGA) to perform correlation process employing the inbuilt multipliers and look up tables and the other one uses Graphical Processing Unit (GPU) to do parallel processing of the input scene. Also in this thesis a detailed analysis of SPOT-MACH has been carried out by comparing with popular feature based techniques like Scale Invariant Feature Transform (SIFT) and a comparison matrix has been created. The proposed filter uses a two-staged approach using speed optimizations and then detection of targets from input scenes. Both visible and Forward Looking Infrared (FLIR) imagery data sets have been used to test the performance of filter.
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Allain, Tituan. "Preuve de concept expérimentale d'un interféromètre hétérodyne astronomique moyen-infrarouge avec corrélation photonique à haute bande passante et détecteurs à puits quantiques." Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALY065.
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L'émission dans le moyen infrarouge des disques protoplanétaires et des enveloppes stellaires contient de précieuses informations sur leur composition en poussières et en gaz, ainsi que sur les phénomènes qui se produisent au voisinage des étoiles jeunes, comme la formation de planètes terrestres. Pour étudier en détail la physique de ces systèmes dynamiques, il faudrait une résolution inférieure à l’unité astronomique sur des objets à une centaine de parsecs. Une telle résolution ne peut être obtenue que par interférométrie à très longue base car elle correspond à des diamètres de télescope kilométriques. La création d'un interféromètre dans le moyen infrarouge avec de longues lignes de base a été identifiée par l’initiative Planet Formation Imager comme la prochaine étape majeure pour contraindre les modèles théoriques de formation planétaire.Actuellement, les interféromètres infrarouges les plus sensibles, comme MATISSE et GRAVITY au VLTI, reposent sur la recombinaison directe de quelques télescopes. Une telle méthode est difficilement extensible à un grand nombre de télescopes sur des lignes de base kilométriques en raison des pertes en transmission et de l'encombrement des infrastructures. L'interférométrie hétérodyne, largement utilisée dans le domaine radio, pourrait représenter une alternative à l'interférométrie directe car elle ne nécessite pas de recombiner physiquement la lumière des télescopes. Elle repose sur la détection hétérodyne du champ électrique de la lumière à chaque télescope, avec un oscillateur local référencé en phase et des détecteurs moyen infrarouge à grande bande passante. Les signaux résultants sont transmis à un corrélateur qui en extrait les observables interférométriques. Cependant, l'interférométrie hétérodyne moyen infrarouge souffre d'une sensibilité réduite en raison du bruit quantique inhérent à la détection hétérodyne. Pour détecter des objets peu lumineux, des efforts considérables sont nécessaires afin de résoudre les défis techniques et technologiques qui limitent la sensibilité d'un tel système.Mon doctorat se concentre sur les aspects de corrélation et de détection moyen infrarouge de l'interférométrie hétérodyne. L'aspect corrélation consiste à mettre en place et à caractériser le banc de démonstration HIKE (Heterodyne Interferometry Kilometric Experiment) de l'IPAG, à Grenoble. Ce banc utilise un corrélateur photonique analogique constitué de composants télécoms à 1,5 micromètre pour corréler des signaux moyen infrarouge à 10 micromètres, avec des bandes passantes de l'ordre du gigahertz. Une telle expérience de corrélation photonique de signaux moyen infrarouge est une première mondiale. J’ai développé une méthodologie pour caractériser les niveaux de bruit dans le système afin d’identifier les éléments qui dégradent la mesure de la visibilité interférométrique. Mes résultats montrent que le niveau de bruit associé au corrélateur photonique ne dégrade pas le rapport signal sur bruit du système. Ainsi, la corrélation photonique peut être utilisée comme alternative à la corrélation numérique, habituellement utilisée en radioastronomie, mais lourde en calculs numériques.Actuellement, la principale limite de notre système vient des détecteurs commerciaux utilisés pour la détection hétérodyne. J'ai donc étudié la possibilité de remplacer nos détecteurs par des détecteurs à puits quantiques à large bande passante. Ce travail a été réalisé en collaboration avec l'équipe QUAntum physics and Devices (QUAD) du LPENS à Paris, où j'ai caractérisé des détecteurs moyen infrarouge à puits quantiques de type QWIP et QCD utilisant des métamatériaux. En théorie, les larges bandes passantes de ces détecteurs permettraient de détecter plus de signal astronomique. Cependant, malgré des progrès récents, l’efficacité quantique de ce type de détecteurs reste actuellement trop faible pour notre application d’interférométrie hétérodyne. De nouvelles avancées technologiques sont nécessairesThe mid-infrared emission from protoplanetary disks and stellar envelopes carries precious information about their dust and gas composition and the phenomena occurring in the vicinity of young stars, like the formation of terrestrial planets. To study the underlying physics of such dynamical systems, astronomical instruments require a resolution below the astronomical unit on objects a hundred parsecs away. This resolution can only be achieved with long-baseline interferometry because it corresponds to telescope diameters of a few kilometres. The Planet Formation Imager initiative has identified the creation of a mid-infrared interferometric array with a large number of telescopes as the next major step to constrain the theoretical models that describe planetary formation.Currently, the most sensitive infrared interferometers, like the MATISSE and GRAVITY instruments at VLTI, rely on the direct recombination of light from several telescopes. This method is hardly scalable to many telescopes on kilometric baselines because of transmission losses and the bulkiness of the infrastructures. Heterodyne interferometry, which is widely used in radio-interferometry, has been identified as a possible alternative to direct interferometry in the mid-infrared because it does not require recombining the light from all telescopes physically. Instead, it relies on the heterodyne detection of the astronomical electric field with a phase-referenced local oscillator (a laser) and detecting the intermediate frequency with high-bandwidth detectors. The resulting signals are transmitted to a correlator whose role is to retrieve the interferometric observables from them. However, mid-infrared heterodyne interferometry suffers from reduced sensitivity because of the inherent quantum noise in heterodyne detection. Therefore, to detect weak astronomical objects, considerable efforts must be put to solve the technical and technological challenges that further limit the sensitivity of an heterodyne system.My PhD thesis concentrates on the correlation and detection aspects of mid-infrared heterodyne interferometry. The correlation aspect consists of setting up, operating, and characterising the HIKE (Heterodyne Interferometry Kilometric Experiment) demonstration bench at IPAG, Grenoble. The bench uses an analogue photonic correlator built with commercial telecom components at 1.5 micrometres wavelength to correlate mid-infrared signals at 10 micrometres wavelength with gigahertz bandwidths. Such a set-up is a world premiere. I have developed a methodology to characterise the noise levels inside the system to identify the top offenders that hamper the measurement of interferometric visibility, and implement solutions to improve the sensitivity of the bench. My results show that the noise level associated with the photonic correlator is sufficiently low not to deteriorate the signal-to-noise ratio of the system. Hence, photonic correlation is sensitive enough to be used by heterodyne interferometry as an alternative to the computationally heavy digital correlation that is often used for radio heterodyne interferometry.The current top offenders of our system are the commercial mid-infrared detectors that are used for heterodyne detection. Therefore, to improve the sensitivity of the bench, I have studied the possibility of replacing our detectors with high-bandwidth mid-infrared quantum well detectors. This work has been done in collaboration with the QUAD team at LPENS, Paris, where I have characterised metamaterial enhanced Quantum Well Infrared Photodetectors (QWIP) and Quantum Cascade Detectors (QCD). The high bandwidths of these detectors would represent a significant advantage to detect a larger chunk of the astronomical signal. However, despite recent progress, their quantum efficiencies currently remain too low to obtain a game-changing sensitivity improvement in heterodyne interferometry. Further improvement in the technology is required
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Wood, Christopher. "Higher order statistics in photon-correlation spectroscopy." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267626.
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Northcott, Malcolm John. "Photon limited imaging using the triple correlation." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47593.
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Rouger, Vincent. "Développements méthodologiques pour l'exploration spatio-temporelle des mécanismes de transduction du signal." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4056.
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La membrane plasmique constitue la première entité séparant la cellule de son environnement. A ce rôle de barrière s'ajoute celui de réguler la. Par conséquent, la membrane plasmique est une zone privilégiée pour le passage d'information. Cependant, son étude reste difficile, ne serait-ce que par l'extraordinaire complexité d'organisation de cet assemblage supramoléculaire.Mon projet de thèse vise à développer de nouvelles approches expérimentales pour explorer plus spécifiquement l'organisation et le rôle de la membrane plasmique d'une cellule dans les mécanismes de transduction de l'information. Deux axes ont été privilégiés : le premier, concerne la description de la dynamique d'organisation de la membrane ; le deuxième concerne l'inter-connectivité et la transmission du signal d'une cellule avec d'autres partenaires.Ce manuscrit se compose de plusieurs parties. Le premier chapitre introduira succinctement les questions biologiques. Dans le second chapitre, je présenterai des méthodes utilisées pour l'étude de la membrane. J'y présenterai aussi une série d'observation que j'ai réalisée sur la diffusion de l'EGFR. Le troisième chapitre sera consacré à la technique de corrélation croisée de fluorescence depuis le montage jusqu'à l'étude du modèle EGFR. Dans la quatrième partie, nous verrons comment les collaborations à l'interface biophysique ont permis des développements innovants sur un système de pinces optiques holographiques. J'y présenterai les applications de ce système à différent modèles d'intérêt biologique. Enfin, je conclurai ce document par une brève discussion autour des résultats obtenus aussi bien d'un point de vue méthodologique que biologiqueThe plasma membrane separates the cell from its environment. But it is more than a barrier any cell has to communicate with the outside world. Therefore the plasma membrane plays a prime role in transferring and exchanging information. However, the biological study of the plasma membrane remains difficult due to the extraordinary complexity of it organization.My thesis is a part of an effort to develop new experimental approaches to explore more specifically the organization and the role of the plasma membrane in the signal transduction mechanisms. Two major aspects were followed: the first one concerns the description of the dynamics of membrane organization and of molecular interactions, the second concerns the inter-connectivity and signal transduction between a cell and other biological partners.This manuscript is composed of several parts. The first chapter briefly introduces the biological questions that I tried to answer. In the second chapter, I present the methods commonly used to study the membrane with a dynamic perspective. Additionally, I include a series of observations that I made on the EGF receptor diffusion. The third chapter is devoted to the fluorescence cross-correlation technique to study the assembly of the EGFR. In the fourth part, I demonstrate how scientific collaborations at the interface between biology and physics have led to the development of innovative solutions on a holographic optical tweezers system. I present applications of this system in different biological models. Finally, I conclude this thesis with a brief discussion about my technological and biological results
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Saunders, Dylan John. "Quantum Correlations: Experimental EPR-Steering, Bilocality and Weak Tomography in Photonic Quantum Information Science." Thesis, Griffith University, 2013. http://hdl.handle.net/10072/367406.
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Quantum mechanics has led to the biggest technological breakthroughs of last century.
However, many paradoxes still remain in the foundations of quantum theory. In this research we study one effect that leads to such paradoxes; quantum correlations.
Quantum nonlocality refers to the set of quantum correlations that are not explainable using local models. It is quantum nonlocality that has troubled physicists since the inception of quantum theory nearly 100 years ago. However, these nonlocal quantum correlations offer a range of advantages in quantum information tasks. For example, quantum key distribution and quantum computing are two tasks that are powered by quantum correlations. For this reason a wide range of quantum correlations are studied experimentally in this research. These include: entanglement, EPR-steering, Bell nonlocality and bilocality. We study these correlations using the framework of quantum information, using single photons as our chosen quantum information carriers.
The first quantum correlation tested in this research is EPR-steering. EPR-steering is the application of the EPR-paradox to a quantum information task. We implement three different experiments on EPR-steering. By studying the properties of the quantum information task we find that: EPR-steering is more robust to depolarisation noise than Bell-nonlocality; EPR-steering is absolutely loss tolerant; and tests of EPR-steering are easier to carry out, than tests of Bell nonlocality, but harder to implement compared to tests of non-separability. As a result of these three findings we experimentally show that EPR-steering can be demonstrated on Belllocal states, we close the detection loophole in a photonic test of quantum nonlocality,
and we discover and implement maximally parsimonious tests of non-separability, EPR-steering and Bell nonlocality.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Science, Environment, Engineering and Technology
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Meinecke, Jasmin Denise Annekristin. "Quantum correlations in multi-photon quantum walks." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.701808.
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Quantum particles show a distinct behaviour compared to classical particles. The fundamental principles of superposition and entanglement lead to interference effects, which often seem to contradict common sense trained by classical physics. Within the emerging field of quantum information and computation techniques for harnessing these quantum interference effects for information processing tasks have been developed. A complex interference phenomenon, which is at the heart of theoretical and experimental quantum information, is quantum walks. It describes the movement of quantum mechanical particles within a discretised space and finds applications in designing quantum algorithms and for implementing quantum simulations. This thesis explores multi-photon interference of identical and entangled particles in physically implemented quantum walk structures. In particular, we realise continuous-time quantum walks, using single photons propagating in integrated waveguide arrays. Here, the evolution is given by the continuous evanescent coupling of the photons between neighbouring waveguides. We demonstrate two-photon quantum walks on a one-dimensional line, where we can observe the time evolution by measuring the output distribution of waveguide arrays with varied lengths. Within this work, we investigate boundary conditions and coherence of the evolution. Additional to this, we employ waveguides, laser-written in glass substrate, implementing a quantum walk on a two-dimensional graph structure. We show quantum interference effects between two photons, which are unique to this two-dimensional structure. In a third experiment, we measure the quantum walk of up to five photons. We compare the output statistics of this structured unitary with the output of a random circuit and we construct a metric for verifying quantum interference. Furthermore, we show, that quantum correlations of entangled particles prevail in a noisy environment and .allow the construction of an entanglement witness. Finally, we utilise entanglement for quantum statistics simulations. Here, we can simulate quantum statistics effects, such as Pauli-exclusion.
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Bennet, Adam Joseph. "Optical Experiments on Shared Quantum Correlations." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/365930.
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Shared quantum correlations find application in a wide range of modern quantum information protocols. This thesis presents several optical experiments towards the improved certification of shared quantum correlations, using photonic qubits.
The first experiment demonstrates the Einstein–Podolsky–Rosen (EPR) steering effect with no detection loophole. Polarisation–entangled photon pairs generated in a Sagnac interferometer were used to test new loss–tolerant EPR steering inequalities. To test the robustness of the loss–tolerant EPR steering nequalities, a transmission loss of −4.3dB was introduced using a 1km optical fibre loop, finding inequality violations for n = 10 and n = 16 measurement settings with no detection loophole (equating to a total loss of
87%). The findings demonstrate how the new loss–tolerant protocols can be used to certify the EPR steering effect for arbitrarily high losses, and may find application in one–sided device–independent quantum key distribution protocols.
The second experiment introduces EPR steering in the context of an EPR steering game. The rules of the game allow for certification of shared quantum correlations via EPR steering inequalites without requiring trust in devices or parties external to a quantum referee. In particular, the experiment successfully demonstrates EPR steering in a measurement–device independent framework; a framework which has typically been accessible only through Bell inequality violations. The findings suggest the possibility for quantum–refereed one–sided device–independent quantum key distribution protocols.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Science, Environment, Engineering and Technology
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Carr, James. "Error analysis of X-ray photon correlation spectroscopy measurements." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117183.
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The use of a theory to extract parameters from experimental data requires proper understanding of the statistical variation. Furthermore, the improvement of any experimental technique requires a sound understanding of the sources of error and an accurate model of how experimental parameters effect signal strength and noise. The second order intensity-intensity correlation function is the standard measured quantity in dynamic light scattering and x-ray photon correlation spectroscopy (XPCS) experiments. In this thesis we compare the measured variances of the correlation function to a model based on the statistics of dynamic light scattering. Agreement between the dynamic light scattering model and the x-ray photon correlation spectroscopy data is shown. XPCS experiments are typically conducted with low photon flux and are used to study long time constants. To achieve sufficient statistics area detectors are used. We show that there are appreciable correlations between near neighbour pixels. These correlations reveal important features that must be included to accurately draw conclusions from XPCS experiments.L'utilisation d'une théorie pour extraire des paramètres depuis des données expérimentales nécessite une compréhension des variations statistiques. De plus, l'amélioration d'une technique expérimentale repose sur la compréhension des sources d'erreurs and d'un modèle précis de l'effet des paramètres expérimentaux sur le signal et le bruit. La fonction de corrélation intensité-intensité de deuxième ordre est une quantité de mesure standardisée pour les expériences de diffusion de lumière dynamique et de spectroscopie de corrélation de photons en rayons X (X-ray Photon Correlation Spectroscopy, XPCS). Dans cette thèse, nous comparons les variances mesurées de la fonction de corrélation à un modèle basé sur les statistiques de diffusion de lumière dynamique. Nous démontrons l'accord entre le modèle de diffusion de lumière dynamique et les données XPCS. Les expériences XPCS sont en général effectuées avec un faible flux de photons et sont utilisées pourétudier les constantes à long terme. Pour atteindre des statistiques susantes, de détecteurs à résolution spatiale sont utilisés. Nous montrons l'existence de corrélations entre pixels voisins. Ces corrélations révèlent d'importantes caractéristiques qui doivent tre inclues afin de tirer des conclusions précises des expériences XPCS.
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Ross, Michael McLean. "Photon correlation velocimetry for the fluid flow through turbomachinery." Thesis, University of Leicester, 1988. http://hdl.handle.net/2381/34819.
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This thesis is concerned with the application of photon correlation velocimetry to the design of products which employ rotating components in fluids. Two examples are considered, viz. The development of turbines and compressors for power generation. The development of propulsor design for use on underwater powered vehicles. The former required the measurement of high speed gas flows (up to Mach 1.8) both within cascades and in a model turbine. The latter entailed tests on models in both a water tunnel and a wind tunnel with flow velocities of up to 15 meters per second and 50 meters per second respectively. In each case a 50 nanosecond digital correlator was used and the optical systems were designed to operate within constraints set by this, the nature of the expected flows, the optical access available and the information sought. In all three applications, a backscatter geometry had to be used. Laser Doppler velocimetry was employed in the propulsor design. However, since the upper Doppler frequency limit of the correlator was 10 Mz., the high speeds encountered in the turbine and compressor models necessitated the use of laser transit velocimetry. Details of the systems design, the optics and data reduction software are given. Some experimental results of measurements made within cascades and rotating components are presented and their significance concerning the velocimeters used are discussed. The chief conclusions which are drawn from the work are: In many flow configurations of practical interest in gas and steam turbines, transit velocimetry with photon correlation can be used to measure mean velocity to within 1% and turbulence intensity to within 1%. However, in some regions, particularly where the turbulence intensity exceeds approximately 15%, the results are not easy to interpret. Despite the low upper limit to Doppler frequency that can be managed by the 50 nanosecond correlator, its power in processing low-light-level and noisy signals enabled it to be used effectively with a Doppler velocimeter for the measurement of flows within propulsor blading both in a water tunnel and in a wind tunnel. When used with Doppler velocimetry, the inherent averaging mode of operation of the correlator permitted the measurement of mean velocity to within 1%. It also provided a measure of turbulence intensity, which was self consistent to within 2%, although the relationship between this and the standard deviation of velocity was ambiguous. Analysis of the properties of photon correlation in laser velocimetry indicated scope for future work in two directions. Firstly, photon correlation responds to uncertainties arising from particle and velocity biasing in a different way from other signal processors such as burst counters. By carrying out measurements using both types of processor it may be possible to reduce these uncertainties. Secondly, the power of photon correlation in processing low-light-level signals should permit the use of a convenient backscatter arrangement of a reference beam laser Doppler velocimeter to measure the line-of-sight velocity component.
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Grankin, Andrey. "Theoretical studies of optical non-linear effects in ultracold Rydberg gases." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLO006/document.
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Les photons apparaissent comme des vecteurs d'information fiables, car ils interagissent peu avec leur environnement. Malheureusement, ils interagissent si faiblement entre eux que la réalisation directe de portes logiques optiques à deux qubits est impossible. La propagation à travers des milieux atomiques non-linéaires permet néanmoins d'engendrer des interactions photon-photon effectives. L'utilisation du phénomène de transparence électromagnétiquement induite (EIT) permet d'induire une forte non-linearité résonante -- néanmoins pas encore détectable dans le domaine quantique, sur une transition d'un système à trois niveaux en “échelle”. Pour augmenter les effets non-linéaires et atteindre le régime quantique, il a récemment été proposé de combiner l'approche EIT au blocage d'excitation induit par les fortes interactions dipôle-dipôle entre atomes de Rydberg. En plaçant le milieu en cavité, on impose à la lumière des passages multiples et on accroît encore la non-linéarité optique. Ce type de dispositif a été étudié théoriquement et expérimentalement dans le régime dispersif et pour une non-linéarité faible, pour lequel un traitement classique du champ est adapté. Dans le présent mémoire, nous nous intéressons aux effets optiques non-linéaires induits par un milieu Rydberg dans le régime quantique.Dans le chapitre 1, nous présentons notre système d'étude, ses équations dynamiques et rappelons la définition et les principales propriétés de la fonction de corrélation d'intensité g^{2}que nous utilisons pour caractériser l'action de la non-linéarité sur le champ incident. Dans le chapitre 2, nous considérons le régime dispersif, i.e. lorsque l'état intermediaire est très désaccordé et peut être éliminé adiabatiquement. Nous utilisons l'approximation des bulles Rydberg selon laquelle le système peut être effectivement ramené à un ensemble de superatomes à deux niveaux couplés au mode de la cavité, décrit par le modèle de Tavis-Cummings forcé. Nous calculons analytiquement et numériquement la fonction g^{2}pour la lumière transmise, qui, selon les paramètres de la cavité, peut être “groupée” ou “dégroupée”. Dans le chapitre 3, nous présentons un traitement alternatif du système, qui nous permet d'étudier le régime résonant. Dans la limite d'un champ incident faible, nous dérivons analytiquement la fonction de corrélation g^{2} pour les lumières transmise et réfléchie, grâce à la factorisation des moyennes de produits d'opérateurs à l'ordre le plus bas de la théorie de perturbation. Nous proposons ensuite un modèle effectif non-linéaire à trois bosons pour le système couplé atomes-cavité. Enfin, nous étudions le régime résonant et observons de nouvelles caractéristiques de la fonction de corrélation g^{2}qui attestent la relation entre les conditions d'adaptation d'impédance de la cavité pour les différentes composantes du champ et les interactions dipôle-dipôle entre les atomes. Dans le chapitre 4, nous analysons le système dans le formalisme de Schwinger-Keldysh. En appliquant le théorème de Wick, nous développons perturbativement les fonctions de corrélation par rapport au Hamiltonien d'alimentation de la cavité et au Hamiltonien d'interaction dipôle-dipôle et effectuons une resommation complète par rapport à ce dernier. Nous retrouvons par cette méthode les résultats du Chapitre 3, sous une forme analytique. Nous allons aussi au-delà et derivons des expressions analytiques pour les composantes élastique et inélastique du spectre en transmission de la cavité. Nous identifions une structure de résonance polaritonique, jusque-là inconnue, que nous interprétons physiquement. Dans le chapitre 5, nous décrivons un protocole de porte photonique de phase de haute fidélité fondé sur le blocage Rydberg dans un ensemble atomique placé dans une cavité optique. Ce protocole peut être réalisé avec des cavités de finesse modérée et permet en principe un traitement efficace de l'information quantique codée dans des photonsPhotons appear as reliable information messengers since they interact very weakly with their environment. Unfortunately, they interact so weakly with each other that the direct implementation of optical two-qubit gates is impossible. The propagation through atomic nonlinear media however allows one to achieve effective photon-photon interactions. The technique of electromagnetically induced transparency (EIT) allows one to induce a strong resonant non-linearity -- not strong enough to be noticeable in the quantum domain though, on one of the transitions of a three-level ladder system. To enhance the nonlinear effects and reach the quantum regime, it was recently proposed to combine the EIT approach with the excitation blockade induced by the strong dipole-dipole interactions between Rydberg atoms. By putting the medium in a cavity, one imposes multiple passes to the light therefore increasing the optical nonlinearity. This kind of setup was studied both theoretically and experimentally in the dispersive regime and for a relatively weak nonlinearity, for which a classical treatment of the field is still valid. In this dissertation, we investigate the optical nonlinear effects induced by a Rydberg medium in the quantum regime.In chapter 1, we present our system, its dynamical equations and recall the definition and basic properties of the intensity correlation function g^{left(2right)}that we use to characterize the action of nonlinearity on the photonic field. In chapter 2, we consider the so-called dispersive regime, i.e. when the intermediate state is far detuned and can be adiabatically eliminated. We employ the Rydberg bubble approximation in which the system effectively consists in an ensemble of two-level superatoms coupled to the cavity mode, described by the driven Tavis-Cummings model. We compute analytically and numerically the g^{left(2right)}function of the transmitted light, which, depending on the cavity parameters, is shown to be either bunched or antibunched. In chapter 3, we present an alternative treatment of the system, which allows us to investigate the resonant regime. In the low-feeding limit, we analytically derive the correlation function g^{left(2right)}left(tauright)for the transmitted and reflected lights, based on the factorization of the lowest perturbative order of operator product averages. We then propose an effective non-linear three-boson model for the coupled atom-cavity system. Finally, we investigate the resonant regime and observe novel features of the correlation function g^{left(2right)}showing the interplay of impedance matching conditions and dipole-dipole interactions. In chapter 4, we analyze the system in the Schwinger-Keldysh formalism. Applying Wick's theorem, we perturbatively expand correlation functions with respect to both, feeding and dipole-dipole interactions Hamiltonians and perform a complete resummation with respect to the latter. By this method we recover the results of Chap. 3 in an analytic form. We also go beyond and derive analytic expressions for the elastic and inelastic components of the cavity transmission spectrum. We identify a polaritonic resonance structure in this spectrum, to our knowledge unreported so far, that we physically interpret. In chapter 5, we describe a novel scheme for high fidelity photonic controlled-phase gates using Rydberg blockade in an ensemble of atoms in an optical cavity. This protocol can be implemented with cavities of moderate finesse allowing for highly efficient processing of quantum information encoded in photons
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Geng, Wei. "Coupling nanostructures towards integrated nanophotonics devices." Thesis, Troyes, 2015. http://www.theses.fr/2015TROY0016/document.
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Avec les avantages significatifs de stockage, de traitement et de transmission des informations, la science de l’information quantique a attiré des études abondantes lors des dernières décennies, par lesquelles de nombreuses preuves de principe ont été faite en utilisant des techniques expérimentales macro-photoniques. Cependant, l'applicabilité de ces technologies dépend fortement de la miniaturisation du système, i.e. l'intégration « sur-puce » des fonctionnalités photoniques quantiques. Les conditions prérequis générales d'une puce quantique intégrée sont la génération, le transport et la détection localisée et efficace de photons. Des efforts ont été réalisés avec succès comportant une ou deux fonctions nécessaires. Cependant, l'intégration complète reste encore inachevée. Basé sur des éléments nano-photoniques de semiconducteurs et des techniques de nano-fabrication simples, cette thèse vise à fournir une stratégie d'intégration « sur-puce ». Une excitation efficace et locale d'une source de photon unique par un guide d'onde inférieure à l'échelle de la longueur d'onde est d'abord démontrée. Ensuite, nous étudions l’échange efficace de la lumière entre les nanostructures et les guide d'onde, qui peuvent servir le bloc de liaison entre les dispositifs dans un système d'intégration. La fabrication et la caractérisation d'un photo-détecteur sensible basé sur un nanofil unique sont présentées, qui présente un grand potentiel pour la détection de photons uniques. A la fin, une perspective de l'intégration ultime de toutes ces fonctionnalités est fournieWith the significant advantages in storing, processing and transmitting information, quantuminformation science has attracted abundant studies in the last few decades, by which many proofs ofprinciple have been made using macro-photonic experimental techniques. However, the applicabilityof this technology still strongly depends on the miniaturization of the system, i.e. the on-chip integration of quantum photonic functionalities. The general prerequisites of an integrated quantumchip are localised and efficient generation, transportation and detection of photons. Some effortshave been made successfully involving one or two necessary features. However, the full integration still remains unaccomplished. Based on semiconductor nanophotonic elements and simple nanofabrication techniques, this thesis aims to provide a strategy for on-chip quantum photonic integration. An efficient and local excitation of a single photon source with a subwavelengthwaveguide is firstly demonstrated. Then we investigate the efficient light exchange betweennanostructures and waveguides that can serve as linking blocks between devices in an integrationsystem. The fabrication and characterisation of a sensitive photodetector based on a single nanowireis also presented, which exhibits great potential in single-photon detection. At the end, an outlook ofthe ultimate integration of all these functionalities is provided
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Macfadyen, Allan John. "Photon correlation spectroscopy and electrophoretic light scattering using optical fibres." Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277140.
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Jepras, Robert Ian. "Applications of photon correlation spectroscopy and flow cytometry to microbiology." Thesis, Open University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.290872.
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Dauler, Eric A. (Eric Anthony) 1980. "Experimental study of the frequency correlation of space-time entangled photons." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/16961.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (leaves 57-58).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Space-time entangled photons generated from a continuous-wave parametric downconverter have a well defined sum-frequency despite having individual broad bandwidths. The narrowband frequency correlation that results from this well defined sum-frequency is examined experimentally. The measurements use degenerate, 1.55 [mu]m photon pairs that are also suitable for fiber-based quantum communication protocols. Techniques for optimizing the pair generation rate, the detector and coincidence circuit parameters and the fiber coupling of down-converted light are also presented. A strong frequency correlation is observed using ~0.5 nm bandpass filters to measure the frequencies of entangled photons with >100 nm individual bandwidths.
by Eric A. Dauler.
M.Eng.
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Schwille, Petra. "Zwei-Photonen-Kreuzkorrelations-Spektroskopie : Nachweis der Interaktionen einzelner Moleküle in der lebenden Zelle." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1188552284775-41077.
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The progress of miniaturisation towards the nanoscopic scale in science and technology has also influenced the biosciences. This is particularly important, since proteins, as the smallest functional units of life, exhibit a spectacular wealth of functionalities, enabling them to fulfil complex tasks in cells and organisms. For this reason, they are often termed molecular or cellular “machines”. To be able to investigate and better understand these fascinating molecules in their native environment, new analytical methods must be developed, with appropriately high sensitivity and spatial and temporal resolution. We describe one very promising technique based on fluorescence spectroscopy, which allows a quantitative analysis of protein- protein interactions in the live cellDie zunehmende Miniaturisierung bis hin zum nanoskopischen Maßstab in vielen technischen Disziplinen hat auch die Lebenswissenschaften ergriffen. Dies ist insofern von großer Bedeutung, als die Proteine als kleinste funktionale Einheiten des Lebens trotz ihrer winzigen Abmessungen eine faszinierende Komplexität aufweisen, die es ihnen erlauben, hoch differenzierte und spezialisierte Aufgaben in der Zelle und im Organismus zu übernehmen. Aus diesem Grund werden sie in der modernen Biologie auch als molekulare oder zelluläre „Maschinen“ bezeichnet. Um diese kleinen Wunderwerke zu studieren und ihre Funktionsweise in ihrer natürlichen Umgebung zu analysieren, bedarf es innovativer Technologien, die es erlauben, mit maximaler räumlicher und zeitlicher Auflösung auch einzelne Moleküle in der lebenden Zelle sichtbar zu machen und zu verfolgen. Im Folgenden wird eine von uns entwickelte fluoreszenzspektroskopische Methode vorgestellt, mit deren Hilfe die komplizierten Interaktionen zwischen Proteinen in der lebenden Zelle aufgeklärt werden können
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Heathcote, S. Leigh (Stephanie Leigh). "Understanding colloidal quantum dot excitation with solution photon correlation fourier spectroscopy." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97990.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Chemistry, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 27-29).
Colloidal quantum dots (CQDs) have useful absorption and emission properties but exist in inhomogenous batches. Solution photon correlation fourier spectroscopy (S-PCFS) combines interferometry with fluorescence correlation spectroscopy (FCS) to measure the spectral correlation of the average single fluorophore in a solution. With S-PCFS, the intrinsic emission linewidth of CQDs can be assessed. This linewidth information is related to phonon coupling and gives insight into the separation of holes and electrons in excited CQDs. Experimental considerations and recommendations for troubleshooting a S-PCFS apparatus are also presented here.
by S. Leigh Heathcote.
S.M.
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Stana, Markus, Michael Leitner, Manuel Ross, and Bogdan Sepiol. "Studies of atomic scale diffusion by X-ray photon correlation spectroscopy." Diffusion fundamentals 20 (2013) 102, S. 1-2, 2013. https://ul.qucosa.de/id/qucosa%3A13691.
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Stana, Markus, Michael Leitner, Manuel Ross, and Bogdan Sepiol. "Studies of atomic scale diffusion by X-ray photon correlation spectroscopy." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-183943.
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Bounouar, Samir. "Corrélation de photons sur un émetteur de photons uniques semi-conducteur à température ambiante." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00727393.
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Le travail proposé dans cette thèse est basé sur des expérience de corrélation de photons faites sur un émetteur de photon unique semi conducteur: une boite quantique de CdSe dans un nanofil de ZnSe. La première démonstration d'émission de photons unique d'une boite quantique épitaxiée à température ambiante y est présentée. Pour expliquer ce résultat, nous avons étudie expérimentalement et théoriquement l'efficacité de couplage exciton-phonon et ses conséquences sur l'intensité de l'exciton avec la température. Nous présentons également des résultats optiques portant sur la robustesse de cette structure à haute température. La technique de corrélation de photons est également appliquée sur des boites quantiques chargées. la présence du exciton chargé nous a permis de sondé la structure fine du trio excité, de décrire ses processus de relaxations et d'obtenir une mesure direct du temps de spin flip du trou sur l'état p. Des indication sont également données sur la nature possible du dopage. Nous avons aussi étudié la diffusion spectrale de l'émetteur causée par les fluctuations électroniques de son environnement. Par un travail théorique nous montrons comment interpréter l'effet de l'élargissement phonon de la raie homogène, (processus poissonien) combiné avec l'effet de la diffusion spectral (processus markovien) sur la fonction de corrélation de la demi-raie. Grâce à l'expérience, nous concluons sur la statistique de l'énergie d'émission de l'émetteur à haute température. Nous appliquons cette théorie sur les nanofils et interprétons les dépendances en température et en puissance des fluctuations de l'environnement grâce au modèle de Kubo-Anderson.
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Boucher, Guillaume. "Biphoton Frequency-Correlations Engineering and Measurement with a Semiconductor Microcavity." Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC071.
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Ce travail porte sur l'ingénierie et la caractérisation des propriétés temps-fréquence de paires de photons générées par une source semiconductrice. Ce dispositif utilise la conversion paramétrique à température ambiante pour émettre des paires de photons se propageant dans des directions opposées et aux longueurs d'onde télécom. Une microcavité intégrée à la source permet d'augmenter l'efficacité de l'interaction nonlinéaire par résonance du champ de pompe transverse. Nous présentons la théorie de la conversion paramétrique dans cette source et nous montrons comment les propriétés spatiales et spectrales du faisceau de pompe influencent les propriétés des photons, en particulier leur degré d'intrication en fréquence, permettant un ingénierie souple. La variété d'états pouvant être produits est illustrée à l'aide de l'amplitude spectrale jointe. Deux techniques permettant la caractérisation de l'intensité spectrale jointe ont été implémentées. La première est un spectrographe à photons uniques ; la seconde, basée sur la stimulation du processus de conversion paramétrique, a permis une amélioration dramatique de la résolution et du temps d'intégration. Les deux approches ont permis la démonstration de l'ingénierie des corrélations en fréquences en variant la taille et la courbure du faisceau de pompe. Des exemples d'états plus exotiques et une méthode pour caractériser leur fonction de Wigner chronocyclique sont étudiés théoriquement. La relation entre les propriétés temps-fréquence et le degré d'intrication en polarisation de la paire est aussi exploréeThis work is focused on the engineering and characterization of the frequency-time properties of photon pairs generated with a semiconductor source. This device emits photons propagating in opposite directions at telecom wavelengths using spontaneous parametric down-conversion at room temperature. A microcavity integrated in the source allows the resonance of the transverse pump beam, enhancing the efficiency of the nonlinear interaction. We give a theoretical description of the down-conversion process in the source and we show how the spatial and spectral properties of the pump beam impact the properties of the photons, in particular their degree of entanglement in frequency allowing a versatile engineering. The variety of states that can be produced is illustrated using the Joint Spectral Amplitude. Two techniques allowing the characterization of the Joint Spectral Intensity have been implemented. The first one is a single photon spectrograph. The second one, based on the stimulation of the down-conversion process showed a dramatic improvement in terms of resolution and integration time. Both techniques allowed the demonstration of the frequency correlation engineering by varying the waist and curvature radius of the pump beam. Examples of more exotic states and a technique to characterize their chronocyclic Wigner function are theoretically investigated. The relationship between time-frequency properties and degree of entanglement in polarization of the biphoton is also explored
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Jizan, Iman. "Manipulation and characterisation of two photon spectral correlation states in nonlinear devices." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15751.
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In quantum photonics, the requirement for photon pairs with specific quantum states has led to a demand for a fast, high resolution and accurate characterisation of photon pair sources. However, current quantum methods of characterisation suffer from limited accuracy and resolution, and only consist of intensity measurements that prevent access to phase-sensitive measurement photon pairs. A promising tool that addresses these challenges, uses the classical analogue of nonlinear processes to stimulate photon generation, yielding much higher count rates that allows for a higher resolution and accurate photon pair source characterisation. Furthermore, this classical measurement allows for an innovative method to perform full phase-sensitive quantum tomography of photon pair sources that was previous thought to be experimentally challenging to obtain. This thesis examines and compares the quantum and classical method of characterisation of spectral correlations in χ^3 nonlinear devices; namely two integrated silicon nanowires, and a highly nonlinear fibre. In the first study, we use stimulated nonlinear process to confirm the speed-up of characterisation of photon pairs and demonstrate that additional resolution is gained when compared to the traditional coincidence measurements with no increase in measurement time. By applying this technique with phase-sensitive amplification to another identical silicon nanowire, the first phase sensitive measurements are presented showing details that are otherwise hidden in traditional intensity measurements. Furthermore, phase-sensitive measurement of a highly nonlinear fibre shows that phase-sensitive measurements have excellent sensitivity to small features when compared to the traditional intensity measurements.
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Leach, Joseph R. "PHOTON STATISTICS AND FIELD-INTENSITY CORRELATION OF A CAVITY QED SYSTEM WITH EXTERNAL POTENTIALS." Miami University / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=miami1058466870.
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Denissov, Alexandre. "Conditional homodyne detection and time asymmetric fluctuations of light /." view abstract or download file of text, 2004. http://wwwlib.umi.com/cr/uoregon/fullcit?p3153781.
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Thesis (Ph. D.)--University of Oregon, 2004.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 102 -106). Also available for download via the World Wide Web; free to University of Oregon users.
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Mumba, Mambwe. "EFFECTS OF COUPLING BETWEEN CENTER OF MASS MOTION OF AN ATOM AND A CAVITY MODE: PHOTON STATISTICS AND WAVE-PARTICLE CORRELATIONS." Connect to this document online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1121433361.
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Thesis (M.S.)--Miami University, Dept. of Physics, 2005.Title from first page of PDF document. Document formatted into pages; contains [1], v, 296 p. : ill. Includes bibliographical references (p. 393-396).
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Nahra, Mackrine. "Color Centers in Nanodiamonds for Quantum Optics Applications." Electronic Thesis or Diss., Troyes, 2021. http://www.theses.fr/2021TROY0017.
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L’intérêt de trouver un émetteur quantique émettant des photons uniques à la demande devient de plus en plus important dans le domaine de l'optique quantique. Les centres colorés dans les nanodiamants (NDs) se révèlent être des candidats prometteurs. Cependant, la production de NDs ayant des centres colorés brillants et émettant des photons indiscernables reste un défi. Dans cette thèse, nous étudions les centres colorés du groupe IV, en particulier le SiV- et le GeV-, synthétisés par la méthode haute pression haute température (HPHT). Nous étudions l'effet des différents paramètres de croissance sur les propriétés optiques du SiV- et rapportons la largeur de raie la plus étroite de 6 GHz pour un ensemble de SiV- sous excitation hors résonante. En raison de la faible probabilité de trouver un SiV- unique, nous avons dirigé notre attention vers les GeV- où la probabilité de trouver un photon unique était significativement plus élevée. Ces GeV- possèdent des propriétés spectrales remarquables à température ambiante, y compris une raie à zéro phonon (ZPL) stable et brillante. Nous étudions la dynamique de leur population dans le cadre d'un modèle à trois niveaux. Nous rapportons un taux maximal de comptage d'émission de photons de 1,6 Mcps à saturation et une visibilité en polarisation de 92% de la lumière de fluorescence. Outre la ZPL, nous observons d'autres transitions électroniques situées dans la bande latérale des phonons du GeV-. Nous démontrons que la méthode HPHT produit des SiV- et GeV- dans les NDs ayant des propriétés optiques supérieures pour des applications en optique quantiqueThe emerging field of quantum optics has attracted the interest of finding an accessible solid-state quantum emitter generating single photons on-demand. Color centers in nanodiamonds (NDs) have shown to be promising candidates. However, producing NDs hosting bright and indistinguishable photons from color centers remains challenging. In this thesis, we study group IV color centers, particularly silicon vacancy (SiV-) and germanium vacancy (GeV-), synthesized by the high pressure high temperature (HPHT) method. We study the effect of the different growth parameters on the optical properties of the SiV- at room and low temperature (T) and report the narrowest linewidth of 6 GHz for an SiV- ensemble using off resonant excitation. Due to the low probability of finding a single SiV- center, we turn our attention to GeV- color centers where the probability of finding a single photon source was found to be significantly higher. Single GeV- in NDs with size ranging from 10 to 50 nm showed remarkable spectral properties at room T including a stable and a bright zero-phonon line (ZPL). We study their internal population dynamics in the framework of a three level model with intensity dependent de-shelving. We find a maximum photon emission count rate of 1.6 Mcps at saturation. We also report a polarization visibility of 92 % from the fluorescence light. Besides the ZPL, we analyze the origin of other transitions lying within the phonon sideband. We demonstrate that the HPHT method can produce SiV- and GeV- in NDs with superior optical properties required for quantum optics applications
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Cui, Jian Ph D. Massachusetts Institute of Technology. "Deconstructing the room-temperature emission spectra of nanocrystals using Photon-Correlation Fourier Spectroscopy." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/87126.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 137-152).
The photoluminescence spectrum of an ensemble of emitters is the result of the homogeneous "natural" spectra of single emitters subjected to interparticle inhomogeneities and perturbations from the environment. For semiconductor nanocrystals (NCs), efforts to tune ensemble linewidths for optical applications have focused primarily on eliminating sample inhomogeneities because conventional single-molecule methods cannot reliably build accurate ensemble-level statistics for single-particle linewidths. Photon-correlation Fourier spectroscopy in solution (S-PCFS) offers a unique approach for investigating single-nanocrystal spectra with large sample statistics, without user selection bias, with high signal-to-noise ratios, and at fast timescales. With S-PCFS, we directly and quantitatively deconstruct the ensemble spectra of nanocrystals into contributions from the average single-NC homogeneous linewidth, spectral dynamics, and sample inhomogeneity. First, we discovered that single NCs at room temperature, in contrast to cryogenic temperatures, do not exhibit spectral dynamics on sub-millisecond timescales. Second, the linewidths of these homogeneous spectra were found to vary significantly from batch to batch and subject to synthetic control. Our findings crystallize our understanding of the synthetic challenges facing underdeveloped nanomaterials such as InP and InAs nanocrystals and introduce new avenues for the synthetic optimization of fluorescent nanoparticles. Finally, we have made strides toward understanding the underlying physical processes responsible for the homogeneous spectra of single nanocrystals at room temperature. Through careful synthetic control over the nanocrystal structure and composition, we have been able to understand changes in the homogeneous spectral linewidth in terms of exciton-phonon coupling. Combined with a simple spectral lineshape model, we have worked towards quantitatively understanding exciton-phonon coupling with respect to specific nanocrystal structural and composition parameters.
by Jian Cui.
Ph. D.
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Huang, Zheng. "Dynamic Heterogeneity Analysis of Silica Reinforced SBR Using X-ray Photon Correlation Spectroscopy." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron161978180718311.
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Peck, Marius [Verfasser], Joachim [Akademischer Betreuer] Enders, and Norbert [Akademischer Betreuer] Pietralla. "Correlation experiments in photon-induced nuclear fission / Marius Peck ; Joachim Enders, Norbert Pietralla." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2020. http://d-nb.info/1216997799/34.
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Zhan, Hongxin [Verfasser]. "Time-dependent quantum transport and quantum correlations of interacting electrons and photons / Hongxin Zhan." Konstanz : KOPS Universität Konstanz, 2019. http://d-nb.info/1202713912/34.
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Sarker, Suchismita. "Atom Dynamics of Amorphous Materials by X-Ray Photon Correlation Spectroscopy (XPCS) & Neutron Spectroscopy." Thesis, University of Nevada, Reno, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10619898.
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The mitigation of greenhouse gas emissions on the environment led to the development of non-polluting hydrogen fuel cell use in automobiles. Syngas produced from coal gasification is converted to H2 and CO2 gasses by the water shift reaction. Metallic membranes are used to separate H 2 from CO2 and other gasses obtained from the water shift reaction of coal-derived syngas. Commercial crystalline Pd-Ag membranes are widely used for this purpose; however, Pd is an expensive strategic metal. Thus, inexpensive Ni-Nb-Zr alloys are studied.The permeation property of amorphous membranes are known, however, the mechanism of permeation and the nature of the local atomic order of the amorphous membranes was not fully understood.
In this study, atom dynamics studied by synchrotron x-ray photon correlation spectroscopy (XPCS) showed the movement of heavier elements such as Ni, Nb, and Zr, at room temperature and 373K. The addition of hydrogen significantly accentuates the motion of atoms as the hydrogen occupies the tetrahedral sites within the icosahedra leading to expansion and short-range diffusion, and no long-range diffusion is observed estimated to be ∼10-22 m2/s. Vacuum removal of hydrogen from these membranes showed a contraction of the icosahedra and approached to its original position. This suggests that the process reversible due to the pressure gradient. The XPCS results did not reveal the specific position of hydrogen atoms in the icosahedra; hydrogen goes into the tetrahedral sites of Zr4 and distorted Nb4 sites as determined by neutron vibrational spectroscopy. Total neutron scattering and DFT-MD simulation determine the short-range order of up to 1.8 nm and the nearest neighbor bond distances. Determination of cluster formation was first attempted by using small neutron scattering, but it did not have appropriate “Q” range. Thus atom probe tomography (APT) was attempted. This APT study revealed Nb-rich and Zr-rich clusters embedded in Ni-rich matrix, whose compositions are reported. DFT-MD simulation reveals interconnected icosahedra in the metal matrix. The atom dynamics (NVS and XPCS), atom probe tomography, total neutron scattering studies are discussed which have implication in the mechanisms of hydrogen permeation in amorphous metallic membranes.
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Falus, Péter 1972. "X-ray photon correlation spectroscopy studies of the dynamics of self-assembling block copolymer structures." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/29371.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2004.Vita.
Includes bibliographical references (p. 224-234).
Several improvements presented to the emerging technique of X-ray Photon Correlation Spectroscopy. These improvements enabled the study of polymer structures, in particular isotropic sponge phases of homo-polymer block copolymer mixtures. An analysis is presented on how to optimize the experimental beamline configuration for achieving the best possible signal-to-noise ratio (SNR) in x-ray photon correlation spectroscopy (XPCS) experiments. A new, fast x-ray detector system is developed for high-throughput, high-sensitivity, time-resolved, x-ray scattering and imaging experiments, most especially x-ray photon correlation spectroscopy (XPCS). The new detector is characterized in detail, and its performance is evaluated in terms of its signal to noise ratio. Data analysis and photon discrimination techniques are discussed in conjunction with the high data rates this detector produces. The improved detector is capable of collecting the same quality XPCS data in fifty times shorter time than previously available detectors. Detailed characterization of polystyrene ethylenebuthylene styrene sponge phase block copolymer samples is presented. Static X-ray scattering is employed to explore the structure of block copolymer sponge phase samples. The dynamics of the polymer samples is probed by X-ray Photon Correlation Spectroscopy, providing the first measurements on the dynamics of a block-copolymer sponge phase. The structural movements are studied at length scales both longer and shorter than the characteristic length scale of the sponge structure.
(cont.) The intermediate scattering function (ISF) is measured in the 2 ms-200 s range of delay times and 0.01-0.2 nm⁻¹ range of wavenumbers. Both the shape and characteristic delay time of the of the ISF is studied versus temperature and concentration of samples. The results are compared with relevant theories.
by Péter Falus.
Ph.D.
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Huang, Yitong. "Investigation of the filler dynamics affected by coupling agent using x-ray photon correlation spectroscopy." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619559445143452.
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Melo, Luna Carlos Andres [Verfasser], and John Henry [Akademischer Betreuer] Reina. "Quantum coherence and correlations in photonic qubits and photoactive hybrid organometallic Perovskite systems / Carlos Andres Melo Luna ; Betreuer: John Henry Reina." Bayreuth : Universität Bayreuth, 2019. http://d-nb.info/1188314025/34.
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Bauer, W., Burkhard Kämpfer, S. Wolf, and Hanns-Werner Barz. "Analysis of hard two-photon correlations measured in heavy-ion reactions at intermediate energies." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-31848.
Full textAbstract:
Analysis of hard two-photon correlations measured in heavy-ion reactions at intermediate energies H.W.Barz1,2, B.Kämpfer1,2, GY. Wolf3,4, W. Bauer5 1Institut für Kern- und Hadronenphysik, FZ Rossendorf, PF 510119, 01314 Dresden, Germany 1Institut für Theoretische Physik, TU Dresden, Momrnsenstr. 13, 01062 Dresden, Germany 3GSI Darmstadt, PF 110552, 64220 Darmstadt, Germany 4KFKI RMKI Budapest, POB. 49, H-1525 Budapest, Hungary MSU Michigan, East Lansing, MI 48824, USA Abstract Recently reported measurements of hard photon correlations in the reactions 36Ar On 27Al at 95 A*MeV, 86Kr on natNi at 60 A*MeV, and 181Ta on 197Au at 39.5 A*MeV are analyzed. A Boltzmann-Ühling-Uhlenbeck transport model is used to describe the photon production by individual nucleon-nucleon collisions. In the lighter systems we find the best agreement with data when taking into account only the photons from first chance collisions of nucleons or photons produced during the Passage of the nuclei, while the model predicts also a considerable late-time emission of photons which leads to a depletion of the calculated correlation function. The accuracy of the present data daas not allow firm conclusions on the reliability of this late time evolution. Our inveatigatiions do not support a recently reported interference pattern in the heavy Ta + Au system.
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Bauer, W., Burkhard Kämpfer, S. Wolf, and Hanns-Werner Barz. "Analysis of hard two-photon correlations measured in heavy-ion reactions at intermediate energies." Forschungszentrum Rossendorf, 1995. https://hzdr.qucosa.de/id/qucosa%3A22011.
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Analysis of hard two-photon correlations measured in heavy-ion reactions at intermediate energies H.W.Barz1,2, B.Kämpfer1,2, GY. Wolf3,4, W. Bauer5 1Institut für Kern- und Hadronenphysik, FZ Rossendorf, PF 510119, 01314 Dresden, Germany 1Institut für Theoretische Physik, TU Dresden, Momrnsenstr. 13, 01062 Dresden, Germany 3GSI Darmstadt, PF 110552, 64220 Darmstadt, Germany 4KFKI RMKI Budapest, POB. 49, H-1525 Budapest, Hungary MSU Michigan, East Lansing, MI 48824, USA Abstract Recently reported measurements of hard photon correlations in the reactions 36Ar On 27Al at 95 A*MeV, 86Kr on natNi at 60 A*MeV, and 181Ta on 197Au at 39.5 A*MeV are analyzed. A Boltzmann-Ühling-Uhlenbeck transport model is used to describe the photon production by individual nucleon-nucleon collisions. In the lighter systems we find the best agreement with data when taking into account only the photons from first chance collisions of nucleons or photons produced during the Passage of the nuclei, while the model predicts also a considerable late-time emission of photons which leads to a depletion of the calculated correlation function. The accuracy of the present data daas not allow firm conclusions on the reliability of this late time evolution. Our inveatigatiions do not support a recently reported interference pattern in the heavy Ta + Au system.
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Beyler, Andrew Paul. "Single-nanocrystal photon correlation : a versatile tool for elucidating basic physics and characterizing applications-relevant properties." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101452.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 299-327).
Single-molecule spectroscopy has been a critical tool for the development and understanding of semiconductor nanocrystals because of their inherent heterogeneity size-dependent properties. In the past two decades, researchers have developed a diverse toolbox of single-nanocrystal techniques and analyses that is capable of elucidating the complex physics of nanocrystal fluorescence and characterizing many of the subtle but important optical properties of nanocrystal samples. This effort has been enabled by the flexible and modular structure of the single-molecule microscope, which offers a multitude of opportunities for shaping the information gained from single-nanocrystal experiments and provides a convenient and powerful framework for creativity in experimental design. In this thesis, we present two investigations that illustrate the full range and versatility of single-nanocrystal spectroscopy and, in particular, of photon correlation analysis. In Part I, we use single-nanocrystal spectroscopy as a tool for elucidating basic physics by investigating the rapid spectral diffusion of individual nanocrystals at low temperature. We develop a technique capable of measuring spectral dynamics over eight orders of magnitude in time ranging form microseconds to hundreds of seconds, and show that we can extract previously unavailable information about the spectral diffusion mechanism. In Part II, we use single-nanocrystal spectroscopy as a tool for characterizing optical properties by devising an experiment to measure the average biexciton quantum yield of nanocrystal samples. This experiment allows us to measure the biexcitonic properties of underdeveloped materials and can serve as a quick and reliable characterization technique to aid in synthetic optimization. Finally, in Part III, we look to the future by highlighting several modifications of existing experiments that could reveal new and exciting insight into nanocrystals.
by Andrew Paul Beyler.
Ph. D.
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Riveli, Nowo. "Direct Photon - Hadron Correlations Measurement in Au+Au Collision at NucleonCenter-Of-Mass Energy of 200 GeV With Isolation Cut Methods." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1407292084.
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Knowles-Van, Cappellen Victoria Leilani. "The effects of ionic strength and aggregation on crystal growth kinetics : an application of photon correlation spectroscopy." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/20786.
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Elmarzugi, Nagib Ali. "Characterization of polymeric gene delivery complexes by atomic force microscopy, transmission electron microscopy and photon correlation spectroscopy." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415684.
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Perrie, W. "Polarisation correlation in the two-photon decay of metastable atomic deuterium and a test of Bell's inequality." Thesis, University of Stirling, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370538.
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Pintori, Giovanna. "Relaxation dynamics in borate glass formers probed by photon correlation at the microscopic and macroscopic length scale." Doctoral thesis, Università degli studi di Trento, 2017. https://hdl.handle.net/11572/368421.
Full textAbstract:
X-ray photon correlation is used to probe the dynamics of the strong glass former boron trioxide and of a series of alkali borate glasses, (M2O)x(B2O3)1-x where M is the alkali modifier (M=Li, Na and K). The decay times Ï„ of the obtained correlation functions in B2O3 are consistent with visible light scattering results and independent of the incoming beam intensity in the undercooled liquid phase; are instead temperature independent and show a definite dependence on the X-ray beam intensity in the glass. We are therefore witnessing an atomic dynamics induced by the X-ray beam.
Furthermore, we clearly demonstrate that the value of Ï„ is related to absorption by investigating a series of alkali borate glass with the same molar ratio and as a function of the alkali modifier. Finally, we highlight the role played by the structure in the X-ray induced dynamics by studying a series of lithium borate glasses with different molar ratios, and by investigating the wave vector dependence.
Despite the observed dynamics is clearly intensity dependent, we obtain very interesting information on glasses not available with other experimental techniques.
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Pintori, Giovanna. "Relaxation dynamics in borate glass formers probed by photon correlation at the microscopic and macroscopic length scale." Doctoral thesis, University of Trento, 2017. http://eprints-phd.biblio.unitn.it/2606/1/Thesis_Pintori.pdf.
Full textAbstract:
X-ray photon correlation is used to probe the dynamics of the strong glass former boron trioxide and of a series of alkali borate glasses, (M2O)x(B2O3)1-x where M is the alkali modifier (M=Li, Na and K). The decay times τ of the obtained correlation functions in B2O3 are consistent with visible light scattering results and independent of the incoming beam intensity in the undercooled liquid phase; are instead temperature independent and show a definite dependence on the X-ray beam intensity in the glass. We are therefore witnessing an atomic dynamics induced by the X-ray beam.
Furthermore, we clearly demonstrate that the value of τ is related to absorption by investigating a series of alkali borate glass with the same molar ratio and as a function of the alkali modifier. Finally, we highlight the role played by the structure in the X-ray induced dynamics by studying a series of lithium borate glasses with different molar ratios, and by investigating the wave vector dependence.
Despite the observed dynamics is clearly intensity dependent, we obtain very interesting information on glasses not available with other experimental techniques.
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Amselem, Elias. "Dynamics of Quantum Correlations with Photons : Experiments on bound entanglement and contextuality for application in quantum information." Doctoral thesis, Stockholms universitet, Fysikum, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-66469.
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The rapidly developing interdisciplinary field of quantum information, which merges quantum and information science, studies non-classical aspects of quantum systems. These studies are motivated by the promise that the non-classicality can be used to solve tasks more efficiently than classical methods would allow. In many quantum informational studies, non-classical behaviour is attributed to the notion of entanglement. In this thesis we use photons to experimentally investigate fundamental questions such as: What happens to the entanglement in a system when it is affected by noise? In our study of noisy entanglement we pursue the challenging task of creating bound entanglement. Bound entangled states are created through an irreversible process that requires entanglement. Once in the bound regime, entanglement cannot be distilled out through local operations assisted by classical communication. We show that it is possible to experimentally produce four-photon bound entangled states and that a violation of a Bell inequality can be achieved. Moreover, we demonstrate an entanglement-unlocking protocol by relaxing the condition of local operations. We also explore the non-classical nature of quantum mechanics in several single-photon experiments. In these experiments, we show the violation of various inequalities that were derived under the assumption of non-contextuality. Using qutrits we construct and demonstrate the simplest possible test that offers a discrepancy between classical and quantum theory. Furthermore, we perform an experiment in the spirit of the Kochen-Specker theorem to illustrate the state-independence of this theorem. Here, we investigate whether or not measurement outcomes exhibit fully contextual correlations. That is, no part of the correlations can be attributed to the non-contextual theory. Our results show that only a small part of the experimental generated correlations are amenable to a non-contextual interpretation.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 5: Submitted. Paper 6: Submitted.
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Coull, Jonathan. "Single-particle production and photon-hadron correlations in proton-proton collisions at next-to-leading order." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104670.
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In this thesis, we study photon production and photon-hadron correlations at next-to-leading order (NLO) in proton-proton collisions, in both the cases of isolated and non-isolated photons. To begin, fundamentals of perturbative Quantum Chromodynamics (pQCD) are reviewed, with an emphasis on describing how to compute spectra for single particle production and correlated pairs at both leading order (LO) and NLO in hadronic collisions. In particular, a discussion of infrared and collinear singularities at NLO will provide a natural introduction to the concept of factorization. These results are then specifically applied to the case of computing photon and pion single-particle cross-sections in proton-proton collisions at Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider(LHC) energies, and compared to experimental data from the PHENIX and CMS experiments respectively. Included in this will be a short study of the theoretical systematic uncertainty generated by the dependence on factorization scales, and a discussion of the modifications needed when moving from inclusive to isolated observables. Following this, double inclusive cross-sections for production of photon-tagged hadrons are computed and compared to data from PHENIX. Once again, a full NLO treatment is given, and the effects of isolation are implemented. We will conclude with a final section on the application of photon-hadron correlations to the tomographic mapping of energy loss in heavy-ion collisions.Dans cette dissertation, nous étudions la production au seconde ordre (NLO) de photons ainsi que la corrélation entre photons durs et hadrons dans les collisions proton-proton. Dans les deux cas est inclus l'effet de l'application de critères d'isolement sur les photons. Nous commençons par une synthèse des résultats fondamentaux de la chromodynamique quantique perturbative (pQCD), dans laquelle nous résumons les méthodes principales pour calculer des sections efficaces aux premier et second ordres. En particulier, nous discutons des singularités infrarouges et colinéaires qui se produisent au seconde ordre, ce qui nous amènera à introduire la théorie de la factorisation. Ces outils sont par la suite utilisés pour calculer les section efficaces pour la production de photons et de pions dans les collisions proton-proton aux énergies atteintes au Relativistic Heavy Ion Collider (RHIC)et au Grand collisionneur de hadrons (LHC). Ces résultats sont comparés aux données des expériences PHENIX et CMS respectivement. Nous étudions aussi l'incertitude théorique due aux choix des échelles de factorisation et la différence entre les sections efficaces inclusives et isolées. Finalement, nous calculons les sections efficaces pour les paires photon-hadron corrélées et comparons les résultats aux données de PHENIX, tout en incluant les effets de second ordre et d'isolement. Nous concluons avec une description qualitative de l'application des corrélations pour établir une tomographie des collisions d'ions lourds.
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Opel, Karsten, Gudrun Hüttig, and Harald Zänker. "Anorganische Kolloide im Wasser der Elbe." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-29039.
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Das Wasser der Elbe auf der Höhe von Dresden enthält anorganische Kolloidpartikel, deren Partikelgrößenverteilung nahezu den gesamten kolloidalen Definitionsbereich (1 nm bis 1 µm) überstreicht und die vor allem aus sekundär ausgeschiedener amorpher Kieselsäure sowie aus Oxyhydroxiden des Fe, Al und Mn bestehen. Als wichtigstes Schwermetall führen sie Zn. Ihre Konzentration liegt unter 5×10-1 mg/l, um etwa Faktor 30 unter der Konzentration der Schwebstoffe des Elbwassers (Partikel >1 µm). Wegen ihrer hohen spezifischen Oberfläche sind die Kolloidpartikel als potentielle Träger für Schadstoffe trotz dieser geringeren Massekonzentration nicht gegenüber den Schwebstoffen zu vernachlässigen. Die in der Elbe gemessene Partikelgrößenverteilung ähnelt derjenigen, die zu einem früheren Zeitpunkt im Rhein gefunden worden war. Auch die chemische Zusammensetzung der Kolloidpartikel in der Elbe ist der der Partikel des Rheins ähnlich. Die Konzentration der Kolloidpartikel in der Elbe war aber um Faktor 5 bis 10 höher als im Rhein. Grund für letzteres ist wahrscheinlich der höhere Gehalt des Elbwassers an gelöstem Kohlenstoff (DOC). Im "Bulk" eines Flusses sind kolloidgetragene Schadstoffe - anders als schwebstoffgetragene - vermutlich fast genauso mobil wie echt gelöste. Unterschiede zwischen den Transportgeschwindigkeiten der kolloidgetragenen und der echt gelösten Spurenstoffe treten in bestimmten Situationen auf, in denen das Wasser den "Bulk" eines Flusses verlässt (Sickerbereich unter dem Fluss, Ästuar). Es werden Schlussfolgerungen über die Rolle von Kolloidpartikeln im Ökosystem eines Flusses gezogen und noch bestehende Forschungsdesiderate benannt.
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Opel, Karsten, Gudrun Hüttig, and Harald Zänker. "Anorganische Kolloide im Wasser der Elbe." Forschungszentrum Rossendorf, 2004. https://hzdr.qucosa.de/id/qucosa%3A21730.
Full textAbstract:
Das Wasser der Elbe auf der Höhe von Dresden enthält anorganische Kolloidpartikel, deren Partikelgrößenverteilung nahezu den gesamten kolloidalen Definitionsbereich (1 nm bis 1 µm) überstreicht und die vor allem aus sekundär ausgeschiedener amorpher Kieselsäure sowie aus Oxyhydroxiden des Fe, Al und Mn bestehen. Als wichtigstes Schwermetall führen sie Zn. Ihre Konzentration liegt unter 5×10-1 mg/l, um etwa Faktor 30 unter der Konzentration der Schwebstoffe des Elbwassers (Partikel >1 µm). Wegen ihrer hohen spezifischen Oberfläche sind die Kolloidpartikel als potentielle Träger für Schadstoffe trotz dieser geringeren Massekonzentration nicht gegenüber den Schwebstoffen zu vernachlässigen. Die in der Elbe gemessene Partikelgrößenverteilung ähnelt derjenigen, die zu einem früheren Zeitpunkt im Rhein gefunden worden war. Auch die chemische Zusammensetzung der Kolloidpartikel in der Elbe ist der der Partikel des Rheins ähnlich. Die Konzentration der Kolloidpartikel in der Elbe war aber um Faktor 5 bis 10 höher als im Rhein. Grund für letzteres ist wahrscheinlich der höhere Gehalt des Elbwassers an gelöstem Kohlenstoff (DOC). Im "Bulk" eines Flusses sind kolloidgetragene Schadstoffe - anders als schwebstoffgetragene - vermutlich fast genauso mobil wie echt gelöste. Unterschiede zwischen den Transportgeschwindigkeiten der kolloidgetragenen und der echt gelösten Spurenstoffe treten in bestimmten Situationen auf, in denen das Wasser den "Bulk" eines Flusses verlässt (Sickerbereich unter dem Fluss, Ästuar). Es werden Schlussfolgerungen über die Rolle von Kolloidpartikeln im Ökosystem eines Flusses gezogen und noch bestehende Forschungsdesiderate benannt.