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1
Sumner, Roger C. "An interferometric method for evaluating holographic materials /". Online version of thesis, 1990. http://hdl.handle.net/1850/10884.
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Williams, Logan Andrew. "Digital Holography for Three Dimensional Tomographic and Topographic Measurements". University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1398436841.
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Schilling, Bradley Wade. "Advances in real-time optical scanning holography". Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09122009-040312/.
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Richardson, Martin J. "Holography : the thinking picture (essays on holography)". Thesis, Royal College of Art, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388183.
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Larkin, Peter C. "Pre-holography". Thesis, University of York, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444703.
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Montelongo, Yunuen. "Scattering holography". Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709277.
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Hjartarson, Örn. "Separation of lobes in Multispectral Digital Holography". Thesis, Umeå universitet, Institutionen för fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-64314.
Testo completoAbstract (sommario):
Through a holographic recording a property from the third dimension, the depth, is obtained in the form of a phase map of the incident light. One wavelength holography will have a unique phase for the depth range corresponding to the wavelength of the light and outside this range the real depth can not be resolved. By introducing more wavelengths to the measurement the unique phase combination of the waves will have a wider range and larger objects can be resolved. Up to six wavelengths can be simultaneous recorded by making them occupy different spatial frequencies. A set of spatial frequencies together describing a property of the wave is referred to as a lobe. For more than 6 wavelengths and a larger depth range produced by a more seldom repeated unique phase combination the individual waves will occupy the same frequencies, i.e. the lobes overlap. The separation of overlapping lobes is essential in order to make precise and time independent measurements of large and/or moving objects. To separate the lobes the complex fields, i.e. the phases together with the amplitudes, were simulated to propagate a distance and again recorded. The propagation leads to a phase shift of the spatial frequencies which reveals the complex fields in the case of two overlapping wavelengths. For three overlapping wavelengths the resolution, i.e spatial frequencies describing the object, has to be reduced in order to determine the individual complex fields. Since the propagation is a linear transformation for the frequencies that do not overlap, only the overlapping elements whose propagation is nonlinear produce new information. The new information gained is therefore independent of the number of wavelengths used which limits the exact determination of the fields to two wavelengths. Through the holographic recording another property of the complex field is obtained which is the superimposed individual intensities. This bounds the complex fields to certain values, i.e. restricts the possible amplitude of the waves. The recording in the two planes produces two intensity distributions which both must be satisfied by the complex fields. The optimization model for this was formulated and a simple optimization algorithm was implemented. Instead of an equality constraint of the intensities the inequality constraint was implemented, mainly due to that the optimization process was out of the scope of the thesis and the inequality constraint resulted in a simple implementation. The result pointed out important properties even though the optimization could not separate the fields satisfactorily for more than three wavelengths. The inequality constraint contains enough information to solve the case of three overlapping wavelengths.
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Blair, Loudon Thomas. "Evaluation of volume holographic optical elements in dichromated gelatin". Thesis, University of Oxford, 1989. http://ora.ox.ac.uk/objects/uuid:cd5f1733-5f7c-4413-a1e1-224d2e229381.
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The use of dichromated gelatin (DCG) for the formation of holographic optical elements is investigated. In particular, a study is made of the possible sources of spurious recording and replay in such diffracting media. The formation of spurious gratings due to boundary mismatch, when recording a transmission grating in air, is investigated. Experimental results are treated using a simple linear theory which is capable of predicting the relative modulation strengths of each of six recorded gratings. The efficiencies of each of these gratings is related to Fresnel's Laws of reflection and therefore the beam ratio. A brief experimental study of the beam ratio is made. It is found that linear theories do not explain replay of gratings recorded at high exposure energies. This is because DCG exhibits a saturating recording characteristic. A theoretical model is developed to verify experimental results of modulation versus exposure energy for the recording of single and double exposure transmission gratings and their subsequent harmonics. This gives good agreement for most cases, however, it does not explain fully the replay of a difference grating formed due to nonlinearities in the double exposure hologram. A coupled wave theory is therefore developed to take account of both multiple grating interactions between the two primary recordings and the recording of a third grating with a spatial frequency equal to the difference of the two fundamental frequencies. The model gives good agreement with experimental results for varying replay angles and wavelengths. DCG is finally used as a tool to investigate the formation of noise gratings in silver halide emulsions. In particular, results are presented for experiments which were performed to study the effect of high angular scatter upon the selectivity of the noise grating and the recording of reflection noise gratings.
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Guler, Michael George. "Spherical microwave holography". Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/15055.
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Hubel, Paul Matthew. "Colour reflection holography". Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257949.
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Das, Diptarka. "TIME DEPENDENT HOLOGRAPHY". UKnowledge, 2014. http://uknowledge.uky.edu/physastron_etds/16.
Testo completoAbstract (sommario):
One of the most important results emerging from string theory is the gauge gravity duality (AdS/CFT correspondence) which tells us that certain problems in particular gravitational backgrounds can be exactly mapped to a particular dual gauge theory a quantum theory very similar to the one explaining the interactions between fundamental subatomic particles. The chief merit of the duality is that a difficult problem in one theory can be mapped to a simpler and solvable problem in the other theory. The duality can be used both ways.
Most of the current theoretical framework is suited to study equilibrium systems, or systems where time dependence is at most adiabatic. However in the real world, systems are almost always out of equilibrium. Generically these scenarios are described by quenches, where a parameter of the theory is made time dependent. In this dissertation I describe some of the work done in the context of studying quantum quench using the AdS/CFT correspondence. We recover certain universal scaling type of behavior as the quenching is done through a quantum critical point. Another question that has been explored in the dissertation is time dependence of the gravity theory. Present cosmological observations indicate that our universe is accelerating and is described by a spacetime called de-Sitter(dS). In 2011 there had been a speculation over a possible duality between de-Sitter gravity and a particular field theory (Euclidean SP(N) CFT). However a concrete realization of this proposition was still lacking. Here we explicitly derive the dS/CFT duality using well known methods in field theory. We discovered that the time dimension emerges naturally in the derivation. We also describe further applications and extensions of dS/CFT.
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Chang, Chi-Ming. "Higher Spin Holography". Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11392.
Testo completoAbstract (sommario):
This dissertation splits into two distinct halves. The first half is devoted to the study of the holography of higher spin gauge theory in AdS$_3$. We present a conjecture that the holographic dual of $W_N$ minimal model in a 't Hooft-like large $N$ limit is an unusual ``semi-local" higher spin gauge theory on AdS$_3\times $S$^1$. At each point on the S$^1$ lives a copy of three-dimensional Vasiliev theory, that contains an infinite tower of higher spin gauge fields coupled to a single massive complex scalar propagating in AdS$_3$. The Vasiliev theories at different points on the S$^1$ are correlated only through the AdS$_3$ boundary conditions on the massive scalars. All but one single tower of higher spin symmetries are broken by the boundary conditions. This conjecture is checked by comparing tree-level two- and three-point functions, and also one-loop partition functions on both side of the duality. The second half focuses on the holography of higher spin gauge theory in AdS$_4$. We demonstrate that a supersymmetric and parity violating version of Vasiliev's higher spin gauge theory in AdS$_4$ admits boundary conditions that preserve ${\cal N}=0,1,2,3,4$ or $6$ supersymmetries. In particular, we argue that the Vasiliev theory with $U(M)$ Chan-Paton and ${\cal N}=6$ boundary condition is holographically dual to the 2+1 dimensional $U(N)_k\times U(M)_{-k}$ ABJ theory in the limit of large $N,k$ and finite $M$. In this system all bulk higher spin fields transform in the adjoint of the $U(M)$ gauge group, whose bulk t'Hooft coupling is $\frac{M}{N}$. Our picture suggests that the supersymmetric Vasiliev theory can be obtained as a limit of type IIA string theory in AdS$_4\times \mathbb{CP}^3$, and that the non-Abelian Vasiliev theory at strong bulk 't Hooft coupling smoothly turn into a string field theory. The fundamental string is a singlet bound state of Vasiliev's higher spin particles held together by $U(M)$ gauge interactions.Physics
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Findeis, Dirk Michael, e Dirk Michael Findeis. "Aspects of holography". Master's thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/23080.
Testo completoAbstract (sommario):
This study was aimed at broadening the knowledge of aspects of holography by examining three areas of importance, namely: i) qualitative holographic nondestructive testing, as applicable to flaw detection, ii) quantitative holographic interferometry and iii) white-light transfer reflection holography, with particular emphasis on the multiplexing principle. The objects used to evaluate the viability of qualitative holographic nondestructive testing were various carbon fibre airframe sections, a ceramic tube and a ceramic mould. The real-time and double-exposure holographic techniques were used to investigate the objects. Hot air was employed as the stress application medium. The results obtained clearly show the viability of holography as a nondestructive testing technique for the detection of debonds, delaminations, cracks, etcetera. In the second part of the study, the zero-order and fringe-counting techniques were applied to a cantilever loading experiment as a means of quantitatively determining the cantilever's displacement. It was determined that displacements with an accuracy of circa 85 % could be obtained by using the abovementioned techniques. In the final part of this study the transfer and multiplexing principles were rigorously examined. As a result, it was found that when reflection holograms were used as masters, excessively dim transfer holograms were produced. Transmission masters produced much brighter transfer holograms and displayed the capability of individually reproducing the images recorded. However, the angle of visibility of the individual images produced was found to be unsatisfactory and therefore warrants further investigation.
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Kaczorowski, Andrzej. "Adaptive aberration correction for holographic projectors". Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/270322.
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This work builds up on the greatest minds of Cambridge Holography: Adrian Cable, Edward Buckley, Jonathan Freeman, and Christoph Bay. Cable and Buckley, developed an OSPR algorithm which was the first to provide high-quality real-time hologram generation using general-purpose hardware while Freeman designed a method to correct arbitrary aberrations. As ingenious as the method was, the calculations were extensively lengthy. Addressing this issue, a variant of OSPR suited for correcting spatially-varying aberration is presented. The algorithm combines the approaches of Cable, Buckley and Freeman to provide real-time hologram generation while incorporating various corrections (aberration, distortion, and pixel shape envelope). A high-performance implementation on a mid-range GPU achieved hologram generation up to 12 fps. Following topic studied is an adaptive optical correction. This work attempts to construct a set of methods, forming an automated testbed for holographic projectors. Each model, after exiting the production line is placed on such testbed, having all of its imperfections characterized. Once calibrated, each model is able to display highest-quality image throughout its life-span. An application of this work to industry was carried in collaboration with Dr Phillip Hands (University of Edinburgh) and LumeJET. Three demonstrators are constructed intending for a cost-effective system for holographic lithography. They are characterized using the developed testbed. Using the supersampled Adaptive OSPR algorithm, the diffraction limit was surpassed 2.75 times allowing to increase the patterning area. This combines approaches of Cable, Buckley, Freeman and Bay to achieve a wide field-of-view and high pixel-count replay field using off-the-shelf components. This thesis is finished describing the work on 3D holography carried with Penteract28. It is shown that the 2D hologram in the presence of spatially-varying aberrations is mathematically equivalent to a 3D hologram. The same implementation of the algorithm can be used to provide real-time 3D hologram generation.
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Sutter, John David. "Viewer-plane experiments with computed holography with the MIT holographic video system". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/29084.
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Lopez, Marcio André Prieto Aparicio. "Microscopia holográfica digital aplicada na análise de tecidos biológicos". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-23032013-124944/.
Testo completoAbstract (sommario):
Este trabalho teve como objetivo a aplicação do Microscópio Holográfico Digital para análise de amostras biológicas, por meio de imagens de parâmetros físicos e informação quantitativa de uma amostra, gerados através de hologramas digitais, o que não ocorre na holografia clássica. O processamento e análise dos hologramas digitais foi efetuada por um programa escrito por meio do software MatLab, empregando o método de Dupla Propagação. São explicados outros métodos para tratamento de hologramas digitais, presentes no programa. O método de Dupla Propagação foi discutido, destacando suas vantagens frente aos outros métodos. Foi aplicado o método de Volkov para a retirada de ambiguidade de fase. O processo de montagem do Microscópio Holográfico Digital foi descrito, por apresentar modificações em relação ao protótipo inicial adotado. Sete amostras foram analisadas no Microscópio Holográfico Digital, três de calibração e quatro para análise - sangue e solução concentrada de proteína denominada Beta2 Glicoproteína tipo I, ou Beta2-GPI. Para calibração, foram realizados testes de formação de imagem, realizando comparação em quatro microscópios descritos e explicados em funcionamento e princípio envolvidos na formação de imagens, utilizando a mesma amostra; e verificação das dimensões de uma amostra, por meio de medição usando ferramentas disponíveis no programa. Uma amostra de sangue de um indivíduo heterozigoto para Hemoglobina S (anemia falciforme) e uma amostra de sangue de um indivíduo homozigoto para hemoglobina A1 (controle normal) foram empregadas na forma de filmes líquidos secos sobre lâminas de vidro (extensão sanguínea). O uso de fixação foi avaliado com a amostra controle. Foram geradas imagens em duas e três dimensões para as amostras biológicas, reproduzindo as estruturas morfológicas de cada. Para a proteína Beta2-GPI, a análise envolveu somente imagens, sem extração de valores; apesar disso, os resultados mostraram possibilidades de aplicações em estudos futuros. Grandezas físicas foram calculadas para dois dos componentes sanguíneos (Plasma e Eritrócito), mostrando valores próximos daqueles conhecidos anteriormente. Entretanto, alguns valores foram considerados estimativas novas, por não se conhecer, até o momento, nenhum cálculo efetuado anteriormente. A análise comprovou a formação de imagens e a capacidade de mensuração oferecida pelo aparelho. Devido ao parâmetro da fase, foi possível extrair informações em três dimensões.This work aimed the implementation of the Digital Holographic Microscope for the analysis of biological samples, using physical parameters images and quantitative data from a sample, both generated through digital holograms, which does not occur in Classical holography. Processing and analysis of holograms were performed by a program written using the MatLab software, applying the Double Propagation method. Other methods for the treatment of digital holograms were explained. The Double Propagation method was discussed, highlighting their advantages over other methods. The method of Volkov was applied for removing phase ambiguity. The Digital Holographic Microscope assembly process was described, because of the modifications made to the initial prototype adopted. Seven samples were analyzed in the digital holographic microscope, three of them for calibration and the other to the analysis - blood and a concentrated solution of a protein called type I Beta2 Glycoprotein, or Beta2-GPI. Calibration tests were made by observing and comparing four image microscopes, described and explained in operation and principles involved in the formation of images, using the same testing sample; and checking the dimensions of another sample through measurement, using digital tools available in the program. Hb S heterozygous (Sickle Cell disease) and Hb A1 homozygous (Control) blood samples were prepared in microscope slide glasses. Images were acquired in two and three dimensions for biological samples, reproducing their morphological structures. For Beta2-GPI, the analysis involved only images, and no values were extracted; nevertheless, the results showed potential applications in future studies. Physical quantities were calculated for two blood components (Plasma and Erythrocyte), showing values closer to those previously known. However, some values were considered new estimates, because there is no knowledge of any calculation made previously, until now, using Digital Holographic Microscopy. The analysis proved the formation of images and the measurement capacity offered by the apparatus. Due to the phase parameter, we were able to extract information in three dimensions.
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Mills, P. A. "Volume holographic infra-red filters in iron doped lithium niobate". Thesis, University of Oxford, 1985. http://ora.ox.ac.uk/objects/uuid:01d6f3ab-692e-40a5-9f60-d67ebee96bd7.
Testo completoAbstract (sommario):
Two collimated laser beams, wavelength O-514 μm are overlapped within a crystal of heavily iron doped lithium niobate to form a one-dimensional volume holographic grating, a few mm long, designed to behave as a highly selective filter at near infra-red wavelengths. A novel recording geometry is described and a variety of diagnostic experiments are undertaken to determine the main characteristics of the grating. A filter fabricated using this method is used to obtain single mode operation from a 1-55 μm semiconductor laser. The historical survey of holography contained in chapter one emphasizes the dynamic properties and applications of photorefractive recording materials. Standard results of two mathematical theories, kinematic and coupled-wave, are used in chapter two to predict the properties of a Bragg grating when replayed with infra-red light. Chapter three details the recording materials suitable for an infra-red filter, followed by a discussion on the concept of 'scaling'. The recording mechanism of iron doped lithium niobate, including its fixing and erasure process, is presented in chapter four as a basis for selecting the most advantageous crystal characteristics. Mathematical models describing the complex dynamic recording process in iron doped lithium niobate are introduced in chapter five. A novel recording geometry involving the use of two prisms is critically described in chapter six, from initial conception to final implementation. The performance of the grating as an infra-red filter is assessed in chapter seven by measuring the angular response of the transmitted and diffracted beams at a wavelength of 1-152 microns. Chapter eight discusses the applications for volume holographic filters, with particular reference to one example. In chapter nine general conclusions are drawn and future directions for research are suggested. A number of appendices are also included.
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Howlett, Isela D., Wanglei Han, Michael Gordon, Photini Rice, Jennifer K. Barton e Raymond K. Kostuk. "Volume holographic imaging endoscopic design and construction techniques". SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS, 2017. http://hdl.handle.net/10150/624713.
Testo completoAbstract (sommario):
A reflectance volume holographic imaging (VHI) endoscope has been designed for simultaneous in vivo imaging of surface and subsurface tissue structures. Prior utilization of VHI systems has been limited to ex vivo tissue imaging. The VHI system presented in this work is designed for laparoscopic use. It consists of a probe section that relays light from the tissue sample to a handheld unit that contains the VHI microscope. The probe section is constructed from gradient index (GRIN) lenses that form a 1: 1 relay for image collection. The probe has an outer diameter of 3.8 mm and is capable of achieving 228.1 lp/mm resolution with 660-nm Kohler illumination. The handheld optical section operates with a magnification of 13.9 and a field of view of 390 mu m x 244 mu m. System performance is assessed through imaging of 1951 USAF resolution targets and soft tissue samples. The system has also passed sterilization procedures required for surgical use and has been used in two laparoscopic surgical procedures. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
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Tapsell, John Peter. "Direct-Write Digital Holography". Thesis, University of Sussex, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487902.
Testo completoAbstract (sommario):
Chapter 1 gives a brief history of the field of holography along with an overview of this thesis. A more detailed description of holography is provided in Chapter 2 along with a discussion of digital holography. Chapter 3 examines the design of a one-step monochromatic hologram printer capable producing white-light viewable transmission holograms created with the aid of an LCOS display system and printed in a dot-matrix sequence. The lens system employed includes a microlens array and an afocal relay telescope which are both quantitatively examined in order to maximise the contrast, diffraction efficiency and depth of view of the final hologram image. A brief overview of speckle reduction techniques and their applicability to pulsed digital holography is presented along with experimental results of the use of a microlens array to reduce speckle effects. Chapter 4 presents an analysis of the unwanted side effects of the angular intensity distribution of a hologram pixel, using a case study for analysis. Chapter 5 examines methods for increasing both the printing speed and resolution of the hologram printer. Chapter 6 describes the analysis and design of a temperature-energy feedback system to correct for pulsed laser instabilities arising from mode beating due to temperature variations. Chapter 7 provides a conclusion to the work and discusses possible future developments.
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Benyon, Margaret. "How is holography art?" Thesis, Royal College of Art, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359209.
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Padilla, Antonio. "Braneworld cosmology and holography". Thesis, Durham University, 2002. http://etheses.dur.ac.uk/4628/.
Testo completoAbstract (sommario):
This thesis is devoted to studying two important aspects of braneworld physics: their cosmology and their holography. We examine the Einstein equations induced on a general (n - 2)-brane of arbitrary tension, embedded in some n-dimensional bulk. The brane energy-momentum tensor enters these equations both linearly and quadratically. From the point of view of a homogeneous and isotropic brane we see quadratic deviations from the FRW equations of the standard cosmology. There is also a contribution from a bulk Weyl tensor. We study this in detail when the bulk is AdS-Schwarzschild or Reissner-Nordstrom AdS. This contribution can be understood holographically. For the AdS-Schwarzschild case, we show that the geometry on a brane near the AdS boundary is just that of a radiation dominated FRW universe. The radiation comes from a field theory that is dual to the AdS bulk. We also develop a new approach which allows us to consider branes that are not near the AdS boundary. This time the dual field theory contributes quadratic energy density/pressure terms to the FRW equations. Remarkably, these take exactly the same form as for additional matter placed on the brane by hand, with no bulk Weyl tensor. We also derive the general equations of motion for a braneworld containing a domain wall. For the critical brane, the induced geometry is identical to that of a vacuum domain wall in (n-l)-dimensional Einstein gravity. We develop the tools to construct a nested Randall-Sundrum scenario whereby we have a "critical" domain wall living on an anti-de Sitter brane. We also show how to construct instantons on the brane, and calculate the probability of false vacuum decay.
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Bazargan, K. "Techniques in display holography". Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/37938.
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Laia, João Nuno De Araújo Lopes. "Holography, holonomy and fermions". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610474.
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Marchesini, Stefano. "X ray fluorescence holography". Université Joseph Fourier (Grenoble), 2000. http://www.theses.fr/2000GRE10012.
Testo completoAbstract (sommario):
Dans de nombreux cas la structure atomique des solides ne peut etre resolue par les techniques traditionnelles de la cristallographie. Cela peut etre le cas, par exemple, pour les etudes locales d'impuretes diluees, les interfaces enterrees et plus generalement les systemes non periodiques. En 1996 une nouvelle methode structurale, l'holographie x a resolution atomique est apparue. Elle a pour origine la technique d'imagerie holographique, inventee par gabor il y a 50 ans. Dans ce travail, nous presentons d'abord le principe et le cadre theorique de l'holographie par fluorescence, fondes sur le concept de source / detecteur interne. Puis nous decrivons les developpements techniques que nous avons progressivement obtenus, afin de transposer cette methode des rayons x de laboratoire vers la source synchrotron esrf ; ceci sous le double point vue du montage experimental et de l'analyse des donnees. Des resultats intermediaires interessants sont l'imagerie des configurations des lignes de kossel et des ondes stationnaires, a partir desquelles des informations structurales - parametre de reseau, symetrie et orientation cristallines - peuvent etre deduites. Puis l'hologramme et la reconstruction atomique de monocristaux modeles tels que coo(111) sont presentes, avec - pour la premiere fois, une resolution isotrope de 0,5 a et une qualite d'image qui n'avait pas ete obtenue jusqu'a present. Enfin, la premiere application de l'holographie par fluorescence aux films epitaxiques est donnee. Des differences significatives entre des films d'alliages fept chimiquement ordonne et desordonne ont ete obtenus, ouvrant la voie a l'etude de l'ordre a courte distance directionnel dans de tels systemes, au-dela des possibilites de la spectroscopie xafs. De nouvelles perspectives sont offertes en conclusion, concernant l'holographie atomique resolue en temps, ainsi que - sur la base d'une etude preliminaire d'holographie nucleaire - le potentiel de cette technique pour le magnetisme local et la selectivite en site.
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Bompadre, Silvia G. "Bremsstrahlung x-ray holography /". Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/9716.
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Berthiere, Clément. "Entanglement, boundaries and holography". Thesis, Tours, 2017. http://www.theses.fr/2017TOUR4017.
Testo completoAbstract (sommario):
La notion d’entropie d’intrication a eu un profond impact sur la physique théorique, particulièrement depuis ces dix dernières années. D’abord introduite afin expliquer l’entropie des trous noirs, son champ d’application s’est par la suite ouvert à une grande variété de domaines de recherche, de la matière condensée à la gravitation quantique, de l’information quantique à la théorie quantique des champs. Dans ce contexte scientifique effervescent, l’entropie d’intrication apparait comme un outil central et doit donc intensivement être étudiée. A l’origine de cette thèse se trouve le désir de mieux comprendre cette entropie. D’intéressants développements concernant les effets de bord sur l’entropie d’intrication ont vu le jour récemment. Nous proposons donc d’explorer comment le bord d’un espace affecte l’entropie, en particulier dans la situation où la surface d’intrication intersecte ce bord. Nous présentons des calculs explicites de l’entropie d’intrication en espace plat avec bords. Nous montrons que des termes induits par ces bords apparaissent dans l’entropie et nous soulignons le rôle prépondérant que jouent les conditions aux bords. Nous étudions ensuite la contribution de bord dans le terme logarithmique de l’entropie d’intrication en dimensions trois et quatre. Nous calculons en premier lieu ce terme en théorie des champs pour la théorie N = 4 de Yang-Mills, puis nous répétons ce calcul de manière holographique. Nous montrons que ces deux méthodes de calcul donnent le même résultat, si du côté théorie des champs les conditions aux bords préservent la moitié de la supersymétrie et que du côté gravité l’extension du bord dans le bulk est une surface minimaleThe entanglement entropy has had a tremendous and profound impact on theoretical physics, particularly since the last decade. First introduced in an attempt to explain black holes entropy, it has then found applications in a wide range of research areas, from condensed matter physics to quantum gravity, from quantum information to quantum field theory. In this exciting scientific context, the entanglement entropy has thus emerged as a useful and pivotal tool, and as such justifies the need to be intensively studied. At the heart of this thesis therefore lies the desire to better understand the entanglement entropy. Interesting developments during the recent years concern the boundary effects on the entanglement entropy. This dissertation proposes to explore the question of how the presence of spacetime boundaries affects the entropy, specifically in situations where the entangling surface intersects these boundaries. We present explicit calculations of entanglement entropy in flat spacetime with plane boundaries. We show that boundary induced terms appear in the entropy and we emphasize the prominent role of the boundary conditions. We then study the boundary contribution to the logarithmic term in the entanglement entropy in three and four dimensions. We perform the field theoretic computation of this boundary term for the free N = 4 super-gauge multiplet and then repeat the same calculation holographically. We show that these two calculations are in agreement provided that on the field theory side one chooses the boundary conditions which preserve half of the full supersymmetry and that on the gravity side the extension of the boundary in the bulk is minimal
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Gardell, Fredrik. "Holography of SYK model". Thesis, Uppsala universitet, Teoretisk fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-365188.
Testo completoAbstract (sommario):
The aim of the thesis is to study the AdS/CFT correspondence and the AdS2/SYK connection as a very special example of the duality. While the first part of the thesis contains a review of AdS/CFT correspondence in arbitrary dimensions, the later parts focus on an interesting and speculative connection between the gravitational physics in two dimensional nearly AdS2 spacetime and one dimensional SYK model. More specifically, the connection is realized in terms of certain features of the SYK model in strong coupling limit, which resembles those of nearly AdS2 Jackiw-Teitelboim theory.
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Pano, Yorgo. "Celestial amplitudes and holography". Electronic Thesis or Diss., Institut polytechnique de Paris, 2024. https://theses.hal.science/tel-04719897.
Testo completoAbstract (sommario):
Le principe holographique propose une correspondance entre une théorie de gravitation (quantique) à l'interieur de l'espace-temps et une théorie conforme des champs sur le bord. La meilleur réalisation de cette conjecture est la correspondence AdS/CFT où les observables à l'intérieur d'un espace-temps à courbure négative peuvent être exprimées dans une théorie conforme des champs de codimension 1. Cette correspondance a amené une meilleure compréhension de la gravitation quantique grâce à la symétrie conforme de la théorie du bord. En parallèle, beaucoup de processus physiques tel la diffusion des particules élémentaires sont modelisés dans un espace-temps asymptotiquement plat. Nous pouvons alors nous demander quant à leur nature holographique.Dans cette thèse, nous explorons les propriétés holographiques des amplitudes de diffusion dans des espace-temps asymptotiquement plats. Pour les particules de masse nulle, l'amplitude de diffusion peut être exprimée dans une base d'états propres des transformations de Lorentz en appliquant des transformations de Mellin sur les énergies des particules externes. Nous obtenons ainsi une amplitude céleste qui a les propriétés de transformations d'une fonction de correlation dans une théorie de champs conforme de codimension 2. Toutefois ce changement de base doit prendre en compte le fait que l'amplitude de diffusion exprimée en fonction des quantités de mouvement est divergente et doit être traîtée comme une distribution tempérée, en l'intégrant contre des fonctions test à décroissance rapide à l'infini (packets d'ondes). Dans une première partie, nous construisons alors des amplitudes célestes bien définies en considérant la transformée de Mellin des distributions tempérées. Nous caractérisons alors la transformée de Mellin de l'espace de Schwartz et les amplitudes célestes sont des éléments de son dual topologique. Les crochets de dualité dans l'espace de translation et celle dans l'espace conforme sont ainsi complètement équivalents en utilisant la relation de Parseval pour la transformée de Mellin.On étudie par la suite les symétries de la théorie conforme céleste en un nombre de dimensions arbitraire en utilisant les théorèmes mous. Grâce à des outils de la théorie de représentation conforme nous pouvons classifier leurs symétries associées. Les multiplets conformes en dimension supérieure à deux peuvent être représentés par des colliers célestes dont la structure est beaucoup plus riche que celle en deux dimensions. Cela est dû à une représentation des opérateurs à symétrie mixte. L'existence de descendant primaire dans le multiplets correspond à la conservation des opérateurs mous. Nous présentons ensuite une méthode pour construire les charges topologiques associées. En deux dimensions, nous trouvons que le groupe de symétrie est inifini-dimensionel alors que seulement les groupes de symétrie de dimension finie sont présents en dimensions supérieures. Ces groupes de symétries constituent un sous-groupe des groupes des symétries asymptotiques. Les charges dans le complément de ce groupe ne sont pas des symétries de la théorie conforme céleste mais introduisent des déformations d'une théorie conforme à une autre.Enfin, nous étudions les symétries fermioniques dans les théories N=1 QED supersymétrique et supergravité. Nous construisons ainsi les opérateurs fermioniques sur le bord ainsi que les fonctions d'onde conformes à partir de spinneurs/vecteurs judicieusement choisis. Les transformations larges de supersymétrie sont équivalentes au théorème mous du gravitino et nous identifions le générateur correspondant sur la sphère céleste. Ensuite, nous construisons les charges associées aux théorèmes mous du premier ordre pour le photino et du second ordre pour le gravitino en utilisant le formalisme covariant de l'espace de phase. Les charges SUSY globales lient les multiplets conformes bosoniques à ceux qui sont fermioniquesThe holographic principle puts forward a duality between a theory of quantum gravity in the bulk of spacetime and a conformal field theory at its boundary. The most fruitful realization of this conjecture is the AdS/CFT correspondence where observables in the bulk of a negatively curved spacetime can be recast in a codimension-one CFT. This provides new insight into quantum gravity using the powerful tools of conformal symmetry. However we have motive to explore the possible holographic nature of asymptotically flat spacetimes since they serve as a good approximation for physical phenomena such as particle scattering.We therefore explore holographic properties of the S-matrix in asymptotically flat spacetimes in this thesis. For massless particles, performing a Mellin transform on the energies of the external particles expresses the scattering process in a basis of Lorentz eigenstates. The resulting celestial amplitude transforms as a conformal correlator in a codimension-two celestial CFT. However the scattering amplitude in momentum space is divergent and should be treated as a tempered distribution, i.e. by smearing it against rapidly decreasing test functions (wave packets). We therefore provide a well-defined setting for constructing celestial amplitudes by considering the Mellin transform of tempered distributions. We do so by characterizing the Mellin transform $tilde{mathcal M}^+$ of the Schwartz space. The smearing in momentum space can then be expressed in the new conformal space and the two brackets are shown to be completely equivalent using a Parseval-type relation.After that, we study the symmetries of the putative celestial CFT in an arbitrary number of dimensions using soft theorems. We use tools from conformal representation theory to classify the symmetries associated to conformallysoft operators in celestial CFT (CCFT) in general dimensions d. The conformal multiplets in d>2 take the form of celestial necklaces whose structure is much richer than the celestial diamonds in d=2, it depends on whether $d$ is even or odd and involves mixed-symmetric tensor representations of SO(d). The existence of primary descendants in CCFT multiplets corresponds to (higher derivative) conservation equations for conformally soft operators. We lay out a unified method for constructing the conserved charges associated to operators with primary descendants. In contrast to the infinite local symmetry enhancement in CCFT2, we find the soft symmetries in d>2 to be finite-dimensional.The conserved charges that follow directly from soft theorems are trivial in d>2, while non trivial charges associated to (generalized) currents and stress tensor are obtained from the shadow transform of soft operators which we relate to (an analytic continuation of) a specific type of primary descendants. The symmetry group generated by these charges constitutes a subset of the asymptotic symmetry group. The charges in the complement are not symmetries of the celestial CFT but map one celestial CFT to another. This is analogous to having a conformal manifold.Finally we study fermionic symmetries in N=1 supersymmetric QED and supergravity in four spacetime dimensions. We construct boundary fermionic operators and build the appropriate conformal primary wavefunctions using adequate spinors/vectors. Large supersymmetry transformations are equivalent to the leading soft gravitino theorem and we cast its generator on the celestial sphere. We then provide a spacetime interpretation to the leading soft photino theorem and subleading soft gravitino theorem by building the associated soft charges using the covariant phase space formalism. We also elucidate the role played by global SUSY generators in conformal representation theory: they relate fermionic celestial diamonds to bosonic ones and the conformal multiplets stack into a celestial pyramid
29
Miller, Bo Elliot, e Bo Elliot Miller. "Cavity Techniques for Volume Holography". Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/622970.
Testo completoAbstract (sommario):
Volume Holographic Data Storage Systems (HDSS) has been of interest for almost seven decades, and are now considered as a viable option for Write Once Read Many (WORM) cold data storage applications. Thanks to the Bragg selectivity of thick volume holograms, HDSS stores several hundreds of holograms on top of each other, called multiplexed data pages, by which data recording density can be substantially increased compared to surface recordings. On the other hand, signal intensity upon reconstruction of such multiplexed data pages inversely scales with number of multiplexing squared. Therefore, longer detection time and/or a high power laser along with a large dynamic range material is needed to make HDSS a truly viable "fast and high density" option for WORM applications. Historically, the trade-off between data density and data rate is well recognized. The challenge has been partially solved by continuous efforts such as improvement of materials, optical architectures, opto-mechanical systems and signal processing [1,2]. In this dissertation, we provide an additional pathway for HDSS to further increase both data density and transfer rates which is Cavities Enhancement Techniques for HDSS, to overcome the fundamental tradeoff. Key ideas are: recycling light with cavity to enhance data rate, and increasing number of multiplexing by combining cavity-eigenmode multiplexing, a subset of orthogonal phasecode multiplexing, with angular multiplexing. Based on this idea, we design and demonstrate Cavity-enhanced HDSS in such a way that we increase data rate and/or data density by at least factor of 2 while taking advantage of previous improvements as they are, or only with the minimum amount of modifications. In Section 1, we review history of HDSS and summarize the latest research results of HDSS and requirements on modern optical data storage systems as they relate to our solutions. In Section 2, theory of volume holography is reviewed by emphasizing understanding of angular and orthogonal phase code multiplexing. In Section 3 the theory of cavity enhanced reference arms is presented. We discuss how cavities provide a coherent boost to the beam power, which can be used in recording to alleviate source power requirements and/or increase the data recording rate and demonstrate the enhancement experimentally. Beyond basic enhancement, cavities also enable orthogonal phase code multiplexing via cavity eigenmodes. In Section 4, we experimentally demonstrate angular and orthogonal phase code hybrid multiplexing to overcome the limitation of the maximum number of multiplexing imposed by the geometrical constraints of angular multiplexing. In Section 5, novel aspects of the research are discussed in conjunction with the application of the technology for commercial use. Conclusions and future research direction are addressed in Section 6.
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Reyes, Vasquez David Fernando. "Magnetic configurations in Co-based nanowires explored by electron holography and micromagnetic calculations". Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30356/document.
Testo completoAbstract (sommario):
Les nanofils magnétiques suscitent un intérêt considérable depuis une quinzaine d'années en raison de leur utilisation potentielle pour la spintronique. Leur utilisation potentielle dans des dispositifs exige une description détaillée des états magnétiques locaux des nanofils. Dans cette thèse, j'ai étudié qualitativement et quantitativement les états magnétiques à l'état rémanent de nanofils magnétiques par holographie électronique (EH) et simulations micromagnétiques. Une analyse détaillée a été réalisée sur deux types de nanofils : multicouches Co/Cu et nanofils FeCoCu à diamètre modulé. Les deux systèmes ont été synthétisés par électrodéposition dans des membranes. La combinaison des caractérisations magnétiques, structurales et chimiques locales obtenues dans un TEM avec des simulations micromagnétiques ont permis une description complète de ces systèmes. Pour les nanofils multicouches Co / Cu, j'ai analysé l'influence des épaisseurs de cobalt et de cuivre ou de la structure cristalline de Co sur la configuration magnétique de nanofils isolés. Après l'application d'un champs de saturation dans des directions parallèle et perpendiculaire à l'axe des nanofils, j'ai étudié les configurations magnétiques pour les épaisseurs de Co / Cu suivantes : 25nm / 15nm, 25nm / 45nm, 50nm / 50nm et 100nm / 100nm. Trois configurations principales à la rémanence ont été trouvées : (i) un couplage antiparallèle entre les couches Co, (ii) une structure mono-domaine et (iii) un état vortex. Dans les nanofils Co (25 nm) / Cu (15 nm), en fonction de la direction du champ de saturation, les couches de Co peuvent présenter soit un couplage antiparallèle (champ de saturation perpendiculaire) ou un couplage de type vortex (champ de saturation en parallèle) avec un coeur aligné parallèlement à l'axe du fil. Cependant, 10% des nanofils étudié présente un état mono-domaine quel que soit le champ de saturation parallèle et perpendiculaire. Dans le cas Co (50 nm) / Cu (50 nm) et Co (25 nm) / Cu (45 nm), l'épaisseur plus grande de Cu séparant les couches ferromagnétiques réduit l'interaction magnétique entre des couches de Co voisines. L'état rémanent est donc formé de la combinaison de couches de Co monodomaines orientés perpendiculairement à l'axe du fil et de certains états vortex. Enfin pour la configuration Co (100 nm) / Cu (100 nm), un état monodomaine est observé quel que soit la direction du champ appliqué lors de la saturation. Toutes ces configurations magnétiques ont été déterminées et simulées à l'aide des calculs micromagnétiques jusqu'à ce qu'un accord quantitatif avec les résultats expérimentaux aient été obtenus. J'ai ainsi pu expliquer l'apparition et la stabilité de ces configurations en fonction des principaux paramètres magnétiques tels que l'échange, la valeur et la direction de l'anisotropie et l'aimantation. La comparaison entre les simulations et les résultats expérimentaux ont ainsi servi à déterminer précisément la valeur de ces paramètres. Dans les nanofils FeCoCu à diamètre modulé, une description détaillée de l'influence de la géométrie sur la configuration locale de spins a été réalisée. Les expériences d'holographie électronique montrent une structure magnétique monodomaines avec l'aimantation alignée longitudinalement. Cependant, nous avons trouvé grâce à des simulations micromagnétiques que cette configuration monodomaine est fortement affectée par la variation locale du diamètre. L'étude en particulier du champ de fuite mais aussi du champ démagnétisant à l'intérieur des nanofils a mis en évidence le rôle prépondérant des charges magnétiques aux zones de variation de diamètre. De plus l'aimantation présente une structure plus compliquée qu'un simple alignement le long de l'axe du fil. Enfin les résultats que j'ai obtenus ont abouti à une interprétation différente d'expériences précédentes en MFMMagnetic nanowires have raised significant interest in the last 15 years due to their potential use for spintronics. Technical achievements require a detailed description of the local magnetic states inside the nanowires at the remnant state. In this thesis, I performed quantitative and qualitative studies of the remnant magnetic states on magnetic nanowires by Electron Holography (EH) experiments and micromagnetic simulations. A detailed investigation was carried out on two types of nanowires: multilayered Co/Cu and diameter-modulated FeCoCu nanowires. Both systems were grown by template-based synthesis using electrodeposition process. The combination of local magnetic, structural and chemical characterizations obtained in a TEM with micromagnetic simulations brought a complete description of the systems. In the multilayered Co/Cu nanowires, I analysed how different factors such as the Co and Cu thicknesses or the Co crystal structure define the remnant magnetic configuration into isolated nanowires. After applying saturation fields along directions either parallel or perpendicular to the NW axis, I studied multilayered Co/Cu nanowires with the following relative Co/Cu thickness layers: 25nm/15nm, 25nm/45nm, 50nm/50nm, and 100nm/100nm. Three main remnant configurations were found: (i) antiparallel coupling between Co layers, (ii) mono-domain-like state and (iii) vortex state. In the Co(25 nm)/Cu(15 nm) nanowires, depending on the direction of the saturation field, the Co layers can present either an antiparallel coupling (perpendicular saturation field) or vortex coupling (parallel saturation field) with their core aligned parallel to the wire axis. However, 10% of the nanowires studied present a mono-domain-like state that remains for both parallel and perpendicular saturation fields. In the Co(50 nm)/Cu(50 nm) and Co(25 nm)/Cu(45 nm) nanowires, a larger Cu thickness separating the ferromagnetic layers reduces the magnetic interaction between neighbouring Co layers. The remnant state is hence formed by the combination of monodomain Co layers oriented perpendicularly to the wire axis and some tilted vortex states. Finally for the Co(100 nm)/Cu(100 nm) nanowires a monodomain-like state is found no matters the direction of the saturation field. All these magnetic configurations were determined and simulated using micromagnetic calculations until a quantitative agreement with experimental results has been obtained. I was able to explain the appearance and stability of these configurations according to the main magnetic parameters such as exchange, value and direction of the anisotropy and magnetization. The comparison between simulations and experimental results were used to precisely determine the value of these parameters. In the diameter-modulated cylindrical FeCoCu nanowires, a detailed description of the geometry-induced effect on the local spin configuration was performed. EH experiments seem to reveal that the wires present a remnant single-domain magnetic state with the spins longitudinally aligned. However, we found through micromagnetic simulations that such apparent single-domain state is strongly affected by the local variation of the diameter. The study of the leakage field and the demagnetizing field inside the nanowire highlighted the leading role of magnetic charges in modulated areas. The magnetization presents a more complicated structure than a simple alignment along the wire axis. Finally my results have led to a new interpretation of previous MFM experiments
31
Domènech, Cots Oriol. "Compositeness from Holography and beyond". Doctoral thesis, Universitat Autònoma de Barcelona, 2012. http://hdl.handle.net/10803/96534.
Testo completoAbstract (sommario):
La recerca dels components fonamentals de la natura és l’objectiu primordial de la física de partícules. Des del descobriment de l’àtom, estructures més i més fonamentals s’han descobert, les quals componen la matèria. El Model Estàndar de la física de partícules assumeix l’existència d’una sèrie de partícules considerades fonamentals, incloent el bosó de Higgs. No obstant, hi ha fortes motivacions per creure que almenys algunes d’aquestes partícules són compostes i, de fet, la seva naturalesa es podria revelar a l’LHC. El principal problema de les teories que descriuen partícules compostes és el fet de que, en certs regims, els constituents d’aquestes estan fortament acoblats. El tractament de teories fortament acoblades és un dels reptes més importants en la física de partícules actual ja que aquest tipus de teories no poden ésser tractades en el marc de la Teoria Quàntica de Camps, que és l’eina principal en la física teòrica d’altes energies. L’estudi de models en dimensions extra ha aportat una visió més profunda d’aquest problema, ja que aquests models es poden entendre com teories ‘hologràfiques’ que exhibeixen una dinàmica d’acoblament fort. El propòsit d’aquesta tesis és l’estudi de diferents sistemes de partícules compostes. Ens centrem en el desenvolupament de models en dimensions extra que es poden considerar com anàlegs a sistemes fortament acoblats presents a la natura, aquests són la Cromodinàmica Quàntica i els sistemes superconductors. A més també analitzem el cas de la naturalesa composta dels quarks de manera genèrica a través de l’estudi dels efectes de models explícits a energies inferiors a l’escala de nova física.The search for compositeness is a paramount goal in particle physics. Since the discovery of the atom, more and more fundamental structures have been discovered in nature from which matter is compound. The Standard Model of particle physics assumes the existence of a set of fundamental particles, including the Higgs boson, that possess no structure. Nevertheless there are strong motivations to believe that at least some of them could be composite and indeed its nature could be unraveled at the LHC. The main difficulty of theories of composite particles is that, in certain regimes, their constituents are strongly coupled. Dealing with strongly coupled theories is a major puzzle in theoretical physics since they can not be understood in the usual framework of Quantum Field Theories, which is the main tool available in theoretical high energy physics. Fortunately, the study of extra dimensional theories has allowed us to gain deeper insights on this issue since these models can be viewed as ‘holographic’ theories exhibiting strong dynamics. The purpose of this thesis is the study of different composite systems which exhibit strong dynamics. We focus on the development and study of extra dimensional models which can be interpreted as analogs of some strongly interacting systems present in nature, these are Quantum Chromodynamics and superconducting systems. Moreover we also analyze the case of quark compositeness in a model independent way by studying the effects of explicit models at energies below the cut-off scale of New Physics.
32
Newell, John Christopher William. "Optical holography in dichromated gelatin". Thesis, University of Oxford, 1987. http://ora.ox.ac.uk/objects/uuid:df0f4182-1743-47bf-a7f9-d90c312cd2e1.
Testo completoAbstract (sommario):
Chapter 1 contains an introduction to holography, holographic optical elements and coupled wave theory. Chapter 2 contains a detailed review of dichromated gelatin based on published literature and on experimental observations made during work for this thesis. In Chapter 3 the non-linearity of the recording characteristic and changes in the bulk properties of the material during processing are determined. In Chapter 4 the non-uniformity of planar gratings is investigated by making a detailed comparison with a coupled wave theory in which the grating parameters are functions of depth. The effect of different processing procedures on these non-uniformities is demonstrated. In Chapter 5 the mechanism behind the formation of real-time gratings in dichromated gelatin is determined by applying a dynamic form of coupled wave theory. The source of diffraction is found to be a pure absorption grating. In Chapter 6 the use of dichromated gelatin as a medium for copying holograms and for recording efficient noise gratings is demonstrated. In Chapter 7 a theoretical model of holographic optical elements based on vectorial coupled wave theory is presented and is used to investigate the effects of polarisation. In Chapter 8 an optical method for the measurement of distance is developed using the dispersive properties of an on-axis holographic lens. Conclusions are then presented in Chapter 9.
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Iqbal, Nabil. "Holography and strongly correlated systems". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68873.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 221-231).
In this thesis we apply techniques arising from string theory - gauge-gravity/duality, or holography - to problems associated with strongly coupled quantum field theories under extreme conditions such as finite temperature or density. We first study a strongly coupled field theory at finite temperature. We demonstrate that its low frequency limit is determined by the horizon geometry of its gravity dual, i.e. by the "membrane paradigm" fluid of classical black hole mechanics. Thus generic boundary theory transport coefficients can be expressed in terms of geometric quantities evaluated at the horizon, providing a simple understanding of results such as the universality of the shear viscosity in theories with gravity duals. Away from the low frequency limit we find a nontrivial radial flow from the black hole horizon to the boundary of the spacetime; we derive equations governing this flow and demonstrate their use in the simple examples of charge and momentum diffusion. Next, we turn to the study of strongly coupled theories with a finite density of a U(1) charge. The near-horizon geometry of the gravity dual of such a state has an AdS 2 factor, indicating the existence of a nontrivial emergent conformal symmetry in the infrared with nontrivial scaling only in the time direction. We review earlier work indicating that fermionic perturbations of such a state reveal non-Fermi-liquid behavior, i.e. gapless fermionic excitations that are not those of Fermi liquid theory. We perform a one-loop calculation in the bulk to compute the contribution from these Fermi surfaces to the conductivity of the full system. Interestingly, within this class of non-Fermi liquids we find examples whose single-particle spectral function and transport behavior both resemble those of strange metals, i.e. the anomalous metallic state existing in the real-life high Tc cuprates above their superconducting transition temperature. In particular, for these examples the contribution to the conductivity is inversely proportional to temperature. In our treatment these properties can be understood as being controlled by the scaling dimension of the fermion operator in the emergent IR fixed point. We then turn to models of symmetry breaking in holographic models at finite density. We observe that the presence of the AdS₂ factor can result in the condensation of a neutral scalar operator. This can be used to model an "antiferromagnetic" phase in which a global SU(2) symmetry is broken down to U(1). We study the collective modes of the ordered phase and recover the expected spin waves from a gravitational treatment. We then note that the phase transition can be driven to zero temperature by tuning various bulk couplings, resulting in a quantum phase transition of the Berezinskii-Kosterlitz-Thouless type. We study this transition in detail, revealing novel critical behavior, including locally quantum critical dynamics and the existence of an infinite tower of excited states related by a discrete subgroup of the original emergent conformal symmetry. Throughout this thesis we focus on how the novel viewpoint provided by holography can help us gain new insights into the physics of strongly correlated systems.
by Nabil Iqbal.
Ph.D.
34
Klein, Arno. "Dispersion compensation for reflection holography". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/29124.
Testo completo
35
Roberts, Daniel Adam. "CHAOS, holography, and other science". Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104531.
Testo completoAbstract (sommario):
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 167-[177]).
This thesis focuses on the relationship between black holes in holography, chaos in strongly-coupled quantum systems, and the computational complexity of holographic states. By directly considering the time evolution of local operators, I am led to a simple diagnostic of many-body chaos: a commutator of such operators separated in time and space. Using this diagnostic, I study the growth of operators-a manifestation of the butterfly effect-in a variety of quantum systems. By considering the butterfly effect in holography, I find evidence for a detailed correspondence between the tensor network (or quantum circuit) that builds the holographic state and the interior geometry (or Einstein-Rosen bridge) of the black hole. Ultimately, I try to understand these connections by considering entanglement across time: the entanglement between an output system following time evolution and a record or memory perfectly correlated with the initial system.
by Daniel Adam Roberts.
Ph. D.
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Paulos, Miguel Fernandes. "Higher derivative actions and holography". Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608861.
Testo completo
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Christmas, Jamieson Leigh. "Real time holography for displays". Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608741.
Testo completo
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Twitchett, Alison Claire. "Electron holography of semiconductor devices". Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619581.
Testo completo
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Chunlen, Suphakorn. "Finite-size effects in holography". Thesis, Durham University, 2013. http://etheses.dur.ac.uk/9494/.
Testo completoAbstract (sommario):
We study holography in the sense of the anti-de Sitter/conformal field theory (AdS/CFT) correspondence, where the field theory lives in a compact space. We first review some aspects of the AdS/CFT duality. We then discuss our work on finite-size corrections to the drag force exerted on a quark in the quark-gluon plasma. Interestingly, the finite-size effects yield a drag force with decreased magnitude, which is opposite to what is seen in many situations with Newtonian fluids. We then turn to meson excitations in a holographic description of N=2 supersymmetric Yang-Mills theory at finite size. In contrast to other related systems reported in the literature, the first meson excitation is an SO(4) charged scalar meson instead of a vector. Intriguingly, there is also a cross-over between the vector and scalar meson spectra as a function of the system size. Finally, we discuss the extension of this system with a magnetic Kalb-Ramond field. We find intriguing new structure in the phase diagram of the system, and investigate possible causes for an apparent mass gap in the spectrum.
40
Li, Yan. "Digital holography and optical contouring". Thesis, Liverpool John Moores University, 2009. http://researchonline.ljmu.ac.uk/4539/.
Testo completoAbstract (sommario):
Digital holography is a technique for the recording of holograms via CCD/CMOS devices and enables their subsequent numerical reconstruction within computers, thus avoiding the photographic processes that are used in optical holography. This thesis investigates the various techniques which have been developed for digital holography. It develops and successfully demonstrates a number of refinements and additions in order to enhance the performance of the method and extend its applicability. The thesis contributes to both the experimental and numerical analysis aspects of digital holography. Regarding experimental work: the thesis includes a comprehensive review and critique of the experimental arrangements used by other workers and actually implements and investigates a number of these in order to compare performance. Enhancements to these existing methods are proposed, and new methods developed, aimed at addressing some of the perceived short-comings of the method. Regarding the experimental aspects, the thesis specifically develops:• Super-resolution methods, introduced in order to restore the spatial frequencies that are lost or degraded during the hologram recording process, a problem which is caused by the limited resolution of CCD/CMOS devices.• Arrangements for combating problems in digital holography such as: dominance of the zero order term, the twin image problem and excessive speckle noise.• Fibre-based systems linked to tunable lasers, including a comprehensive analysis of the effects of: signal attenuation, noise and laser instability within such systems.• Two-source arrangements for contouring, including investigating the limitations on achievable accuracy with such systems. Regarding the numerical processing, the thesis focuses on three main areas. Firstly, the numerical calculation of the Fresnel-Kirchhoff integral, which is of vital importance in performing the numerical reconstruction of digital holograms. The Fresnel approximation and the convolution approach are the two most common methods used to perform numerical reconstruction. The results produced by these two methods for both simulated holograms and real holograms, created using our experimental systems, are presented and discussed. Secondly, the problems of the zero order term, twin image and speckle noise are tackled from a numerical processing point of view, complementing the experimental attack on these problems. A digital filtering method is proposed for use with reflective macroscopic objects, in order to suppress both the zero-order term and the twin image. Thirdly, for the two-source contouring technique, the following issues have been discussed and thoroughly analysed: the effects of the linear factor, the use of noise reduction filters, different phase unwrapping algorithms, the application of the super-resolution method, and errors in the illumination angle. Practical 3D measurement of a real object, of known geometry, is used as a benchmark for the accuracy improvements achievable via the use of these digital signal processing techniques within the numerical reconstruction stage. The thesis closes by seeking to draw practical conclusions from both the experimental and numerical aspects of the investigation, which it is hoped will be of value to those aiming to use digital holography as a metrology tool.
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Woodhead, William Robert. "Applications of holography and entanglement". Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/415894/.
Testo completoAbstract (sommario):
In this thesis we will investigate a number of topics on the applications of the gauge-gravity duality to topics in condensed matter physics and quantum entanglement. This duality is a conjectured equivalence between type IIB string theory on asymptotically anti-de Sitter backgrounds with certain quantum field theories in one dimension less. Using this conjecture we can model strongly-coupled quantum systems using classical gravity duals which provide novel methods for calculating otherwise computationally inaccessible quantum properties. We will use this for the following applications: • We study a novel method for introducing broken translational symmetry into a holographic model whilst retaining homogeneity in the field equations. We demonstrate that this leads to a finite DC conductivity and shows features of heavy fermion models in the AC conductivity. • We explore the nature of real time scalar correlators in holographic models of critical systems that possess a non-relativistic scaling symmetry. Specifically we explore systems with dual Schrödinger or Lifshitz scaling symmetries, and discuss the problems that arise when trying to apply the standard framework of real time holography to these systems. • We provide an explicit counterexample to the holographic F-theorem, and an analytic argument that shows that this violation is not specific to the model in consideration but is rather a more general property of a class of holographic systems. • Finally we introduce a holographic renormalization scheme for the entanglement entropy based on the standard framework of holographic renormalization. We connect this to the field theory via the replica trick and use it to calculate a number of explicit examples both analytically and numerically.
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Saleh, Walid. "In-line optical fiber holography". Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/41970.
Testo completo
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Dzikevych, A. V., e L. V. Roienko. "Holography as a teaching method". Thesis, Таврійський державний агротехнологічний університет імені Дмитра Моторного, 2021. https://er.knutd.edu.ua/handle/123456789/18853.
Testo completoAbstract (sommario):
У статті мова йде про використання інноваційних технологій, а саме голограм, у навчальному процесі. У дослідженні описано можливість створення тривимірних об'єктів, що є подібними до реальних за допомогою голографічних технологій.The article deals with the issue of using innovative technologies, namely holograms in the educational process. The possibility of creating three-dimensional objects that are similar to real ones with the help of holographic approach has been analysed in the given research.
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Vo, Huy Nhu. "High-resolution Optical Scanning Holography". Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/32527.
Testo completoAbstract (sommario):
Optical scanning holography, which was proposed by Poon[1], is a fascinating technology to record holographic information. The technique is applied in the operation of scanning holographic microscopy to record the entire three-dimensional volume of a biological specimen in the form of a hologram. With the data captured, a digital reconstruction or decoding is used to reconstruct the hologram of that such specimen. An accurate reconstruction of the recorded data provides with an in-depth analysis in the area where random noise and other imperfection effects may occur. In this thesis, three different approaches of reconstruction process are presented to provide in high-resolution a comparison between theoretical and experimental reconstruction a hologram of fluorescent beads. The first approach is to use only the experimental pinhole hologram recorded to correlate with the hologram of the object to give the reconstruction of the section. The second approach is to use the propagated pinhole hologram to reconstruct at an arbitrary depth. Finally, the third approach is to reconstruct without using the experimental pinhole hologram but with diffraction theory. Comparing these results in high-resolution gives us analysis of the reconstruction noise due to optical aberration.Master of Science
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Akin, Enver Turan. "Investigations of Horizontal-Parallax-Only Optical Scanning Holography (HPO-OSH) through MATLAB Simulations". Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/32430.
Testo completoAbstract (sommario):
The concept of generating horizontal-parallax-only (HPO) holograms by computer simulations is investigated. The simulations in this thesis are based on Optical Scanning Holography (OSH) aimed at acquiring HPO information electronically. The principles of OSH, a technique that allows the extraction of 3-D information by a 2-D optical scan of the object is first summarized. The HPO principles and simulation scenarios are then discussed. In order to illustrate the ideas, holograms were created and reconstructed using MATLAB simulations. The holograms are simulated by convolving the Fresnel zone plates (FZP) with the object. The simulations focus on generating HPO holograms using 1-D FZPs modeled as 1-D Gaussian chirp beams of varying waists. An optical reconstruction scheme by cylindrical lens was proposed and simulated. Three-dimensional imaging using HPO-holograms was also discussed. Several reconstruction scenarios were investigated by digitally convolving the complex HPO-hologram with the free space impulse response or the Gaussian chirp beam. Although many ideas of HPO-holography have been proposed and studied, to the best of our knowledge, this is the first proposed electronic technique to acquire HPO-holographic information. The simulations demonstrate that holographic information reduction techniques also help to alleviate the problems associated with the restricted field of view upon holographic reconstruction for 3-D display. The simulations show that horizontal-parallax-only holography is an excellent way to reduce holographic information. Suggested future work includes actual optical experimentation to verify the ideas presented in this thesis.Master of Science
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Abeywickrema, Haburugala Vithanage Ujitha A. "Applications of Induced Gratings in Nonlinear Media". University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1429985534.
Testo completo
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Ziegler, Remo. "Holography and wave-based image generation /". Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17823.
Testo completo
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Smedbäck, Mikael. "Topics on D-branes and Holography". Doctoral thesis, Uppsala University, Department of Theoretical Physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4478.
Testo completoAbstract (sommario):
We discuss various aspects of D-branes in string theory and holography in string theory and loop quantum gravity.
One way to study D-branes is from a microscopic perspective, using conformal field theory techniques. For example, we investigate the question of how D-branes can be introduced into orbifolded theories. Another way to study D-branes is from a space-time perspective. An example is provided by unstable D-branes, where we compute an effective action describing the decay of a bosonic D-brane.
The holographic principle is a proposed duality which suggests that a theory in any region has a dual description on the boundary. We explore two examples: (1) The area law for the entropy of a black hole in the framework of loop quantum gravity, related to particular regularizations of the area operator. (2) The AdS/CFT correspondence proposal, where we investigate a string pulsating on AdS using spin chains.
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Redigolo, Diego. "Supersymmetry Breaking from Holography to Colliders". Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/219162.
Testo completoAbstract (sommario):
We investigate several aspects of four dimensional supersymmetric gauge theories with the minimal amount of supercharges both from the theoretical and the phenomenological view point. On the theoretical side we investigate the behavior of two-point correlators of short multiplets for vacua that spontaneously break supersymmetry. The main goal is to build up an exhaustive description of the supersymmetry breaking dynamics that it is easily extendable to strongly coupled gauge theories. When strong coupling is involved we study the behavior of two-point correlators by means of AdS/CFT techniques building up models of strongly coupled hidden sectors that break supersymmetry and can be described holographically by gauged supegravity in five dimensions. These hidden sectors have also some phenomenological interest in particle physics beyond the Standard Model since they can be used as supersymmetry-breaking sectors in models where the breaking of supersymmetry is mediated by gauge interactions. On the more phenomenological side we study how the Higgs mass requirements constraints gauge mediation models and what could be possible interesting signatures of these scenarios at LHC.Doctorat en sciences, Spécialisation physique
info:eu-repo/semantics/nonPublished
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Mann, Christopher J. "Quantiative biological micrsocopy by digital holography". [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001709.
Testo completo