Дисертації з теми "Quantum optimization"
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Arvidsson, Elisabeth. "Optimization algorithms for Quantum Annealing." Thesis, KTH, Fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279447.
Повний текст джерелаPye, Cory C. "Applications of optimization to quantum chemistry." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq23109.pdf.
Повний текст джерелаGosset, David (David Nicholas). "Case studies in quantum adiabatic optimization." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68872.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (p. 139-143).
Quantum adiabatic optimization is a quantum algorithm for solving classical optimization problems (E. Farhi, J. Goldstone, S. Gutmann, and M. Sipser. Quantum computation by adiabatic evolution, 2000. arXiv:quant-ph/0001106). The solution to an optimization problem is encoded in the ground state of a "problem Hamiltonian" Hp which acts on the Hilbert space of n spin 1/2 particles and is diagonal in the Pauli z basis. To produce this ground state, one first initializes the quantum system in the ground state of a different Hamiltonian and then adiabatically changes the Hamiltonian into Hp. Farhi et al suggest the interpolating Hamiltonian [mathematical formula] ... where the parameter s is slowly changed as a function of time between 0 and 1. The running time of this algorithm is related to the minimum spectral gap of H(s) for s E (0, 11. We study such transverse field spin Hamiltonians using both analytic and numerical techniques. Our approach is example-based, that is, we study some specific choices for the problem Hamiltonian Hp which illustrate the breadth of phenomena which can occur. We present I A random ensemble of 3SAT instances which this algorithm does not solve efficiently. For these instances H(s) has a small eigenvalue gap at a value s* which approaches 1 as n - oc. II Theorems concerning the interpolating Hamiltonian when Hp is "scrambled" by conjugating with a random permutation matrix. III Results pertaining to phase transitions that occur as a function of the transverse field. IV A new quantum monte carlo method which can be used to compute ground state properties of such quantum systems. We discuss the implications of our results for the performance of quantum adiabatic optimization algorithms.
by David Gosset.
Ph.D.
Nuñez, Lobato Carlos. "Optimization of MOVPE-grown Quantum Dots for long distance quantum communication." Thesis, KTH, Tillämpad fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-258829.
Повний текст джерелаStojnic, Mihailo Hassibi Babak Hassibi Babak. "Optimization algorithms in wireless and quantum communications /." Diss., Pasadena, Calif. : Caltech, 2008. http://resolver.caltech.edu/CaltechETD:etd-12032007-113628.
Повний текст джерелаBai, Jing. "Optimization of Optical Nonlinearities in Quantum Cascade Lasers." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19797.
Повний текст джерелаAlanis, Dimitrios. "Quantum-assisted multi-objective optimization of heterogeneous networks." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/419588/.
Повний текст джерелаTitiloye, Olawale. "Optimization by quantum annealing for the graph colouring problem." Thesis, Manchester Metropolitan University, 2013. http://e-space.mmu.ac.uk/324247/.
Повний текст джерелаKhalus, Vladislav Ivanovich. "T-COUNT OPTIMIZATION OF QUANTUM CARRY LOOK-AHEAD ADDER." UKnowledge, 2019. https://uknowledge.uky.edu/ece_etds/141.
Повний текст джерелаRava, Andrea Basilio. "Quantum approximate optimization algorithm: combinatorial problems and classical statistical models." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23113/.
Повний текст джерелаAl, Baity Heyam. "A quantum behaved particle swarm approach to multi-objective optimization." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5857/.
Повний текст джерелаAl-Ta'ani, Ola. "Quantum circuit synthesis using Solovay-Kitaev algorithm and optimization techniques." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/19190.
Повний текст джерелаElectrical and Computer Engineering
Sanjoy Das
Quantum circuit synthesis is one of the major areas of current research in the field of quantum computing. Analogous to its Boolean counterpart, the task involves constructing arbitrary quantum gates using only those available within a small set of universal gates that can be realized physically. However, unlike the latter, there are an infinite number of single qubit quantum gates, all of which constitute the special unitary group SU(2). Realizing any given single qubit gate using a given universal gate family is a complex task. Although gates can be synthesized to arbitrary degree of precision as long as the set of finite strings of the gate family is a dense subset of SU(2), it is desirable to accomplish the highest level of precision using only the minimum number of universal gates within the string approximation. Almost all algorithms that have been proposed for this purpose are based on the Solovay-Kitaev algorithm. The crux of the Solovay-Kitaev algorithm is the use of a procedure to decompose a given quantum gate into a pair of group commutators with the pair being synthesized separately. The Solovay-Kitaev algorithm involves group commutator decomposition in a recursive manner, with a direct approximation of a gate into a string of universal gates being performed only at the last level, i.e. in the leaf nodes of the search tree representing the execution of the Solovay-Kitaev algorithm. The main contribution of this research is in integrating conventional optimization procedures within the Solovay-Kitaev algorithm. Two specific directions of research have been studied. Firstly, optimization is incorporated within the group commutator decomposition, so that a more optimal pair of group commutators are obtained. As the degree of precision of the synthesized gate is explicitly minimized by means of this optimization procedure, the enhanced algorithm allows for more accurate quantum gates to be synthesized than what the original Solovay-Kitaev algorithm achieves. Simulation results with random gates indicate that the obtained accuracy is an order of magnitude better than before. Two versions of the new algorithm are examined, with the optimization in the first version being invoked only at the bottom level of Solovay-Kitaev algorithm and when carried out across all levels of the search tree in the next. Extensive simulations show that the second version yields better results despite equivalent computation times. Theoretical analysis of the proposed algorithm is able to provide a more formal, quantitative explanation underlying the experimentally observed phenomena. The other direction of investigation of this research involves formulating the group commutator decomposition in the form of bi-criteria optimization. This phase of research relaxed the equality constraint in the previous approach and with relaxation, a bi-criteria optimization is proposed. This optimization algorithm is new and has been devised primarily when the objective needs to be relaxed in different stages. This bi-criteria approach is able to provide comparably accurate synthesis as the previous approach.
Kim, Dong Kwon. "Optical properties of asymmetric double quantum wells and optimization for optical modulators." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22649.
Повний текст джерелаCommittee Chair: Citrin, David; Committee Member: Dupuis, Russell; Committee Member: Gaylord, Thomas; Committee Member: Rhodes, William; Committee Member: Zhang, Zhuomin.
Semerjian, Guilhem. "Mean-field disordered systems : glasses and optimization problems, classical and quantum." Habilitation à diriger des recherches, Ecole Normale Supérieure de Paris - ENS Paris, 2013. http://tel.archives-ouvertes.fr/tel-00785924.
Повний текст джерелаHadavi, Hamid. "Isometry Registration Among Deformable Objects, A Quantum Optimization with Genetic Operator." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/24286.
Повний текст джерелаMomeni, Pakdehi Davood [Verfasser]. "Optimization of epitaxial graphene growth for quantum metrology / Davood Momeni Pakdehi." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://d-nb.info/1222160439/34.
Повний текст джерелаSong, Katherine Wei. "Fabrication and optimization of light emitting devices with core-shell quantum dots." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82185.
Повний текст джерелаThis 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 (p. 79-84).
Quantum dot light emitting devices (QD-LEDs) are promising options for the next generation of solid state lighting, color displays, and other optoelectronic applications. Overcoating quantum dots (QDs) -- semiconducting nanocrystals of CdSe, PbS, or another similar compound -- with a wide band-gap "shell" has recently been shown to significantly boost QD-LED performance and yield the most efficient accent QD-LEDs to date. This thesis studies fabrication techniques to make bright, efficient QD-LEDs with these "core-shell" QDs. The first part studies the electrophoretic deposition (EPD) of CdSe/ZnS QDs. QD-LEDs conventionally utilize a QD lm that is deposited via spin-casting, a reliable but highly unscalable technique for the deposition of thin, smooth films of QDs for QD-LED applications. Potential advantages of EPD include the ability for deposition onto a variety of substrate shapes and more energetically favorable QD packing. Devices made with EPD QD films exhibit peak efficiencies comparable to those of devices with a spun-cast QD layer and turn-on voltages surprisingly lower than the optical band-gap of the QDs. These results suggest that EPD is a viable alternative to spin-casting for the processing of QD-LEDs. The second part of this thesis explores the role of core-shell QDs in creating bright, efficient LEDs in the near-infrared ([lambda] >1 [mu]m) regime. Infrared QD-LEDs with record brightness and efficiencies are obtained by using QDs in which lead sulfide (PbS) cores are overcoated with a cadmium sulfide (CdS) shell. In situ photoluminescence quantum yield measurements confirm that the QD shell plays a significant role in shielding the emissive QD core from external quenching mechanisms. Finally, fabrication and material considerations for the non-QD layers in the modern QD-LED structure are also discussed. This thesis analyzes different film formation techniques for zinc oxide (ZnO), the electron transport layer in the QD-LEDs, and different materials and thicknesses for the organic hole transport layer.
by Katherine Wei Song.
S.M.
Borneman, Troy W., David G. Cory, and Martin D. Hürlimann. "Signal optimization in inhomogeneous fields: application of quantum optimal control theory troy." Diffusion fundamentals 10 (2009) 12, S. 1-3, 2009. https://ul.qucosa.de/id/qucosa%3A14103.
Повний текст джерелаMori, Yuto. "Path optimization with neural network for sign problem in quantum field theories." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263466.
Повний текст джерелаBryngelsson, Erik. "Manufacturing optimization and film stability analysis of PbS quantum dot solar cells." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-260053.
Повний текст джерелаKvantprickar av halvledande material har en intressant potential att förbättra solcellers verkningsgrad genom en stark absorption inom de infraröda spektrat och ett justerbart bandgap. I detta arbete gjordes ett försök att återskapa en tillverkningsprocess av kvantprickssolceller av PbS, som visat sig framgångsrik vid Uppsala universitet. Två optimeringar undersöktes och stabiliteten av kvantpricksfilmerna analyserades med avseende på tre förvaringsmiljöer med olika exponering för ljus och syre, och mättes med UV-visspektroskopi samt röntgenfotoelektronspektroskopi. Fullt fungerande solceller framställdes men med en lägre prestanda jämfört med resultaten i Uppsala. Optimeringarna var delvis lyckade gällande spridning av EDTlösningen på kvantpricksfilmen av PbS genom att använda etanol och metanol som lösningsmedel. Ingen förbättrad prestanda observerades hos cellerna genom att applicera båda kvantpricksfilmerna i argonatmosfär, jämfört med endast den första. Tydliga skillnader i oxidation för filmerna samt förluster av jodligand kunde identifieras för de olika förvaringsmiljöerna, med bäst stabilitet uppvisad av filmerna som förvarades i argonatmosfär.
Maisel, Sascha B. [Verfasser]. "Characterization and optimization of multicomponent alloys based on quantum mechanics / Sascha B. Maisel." München : Verlag Dr. Hut, 2015. http://d-nb.info/1070123854/34.
Повний текст джерелаHülsen, Michael [Verfasser]. "Optimization of Integral Transformations and Quantum Chemical Calculations on Organometallic Templates / Michael Hülsen." München : Verlag Dr. Hut, 2012. http://d-nb.info/1025821149/34.
Повний текст джерелаBrandeho, Mathieu. "New bounds for information complexity and quantum query complexity via convex optimization tools." Doctoral thesis, Universite Libre de Bruxelles, 2018. https://dipot.ulb.ac.be/dspace/bitstream/2013/277139/4/Main.pdf.
Повний текст джерелаDoctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished
Maisel, Sascha [Verfasser]. "Characterization and optimization of multicomponent alloys based on quantum mechanics / Sascha B. Maisel." München : Verlag Dr. Hut, 2015. http://d-nb.info/1070123854/34.
Повний текст джерелаPang, Bo. "Handwriting Chinese character recognition based on quantum particle swarm optimization support vector machine." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3950620.
Повний текст джерелаJunique, Stéphane. "Surface-normal multiple quantum well electroabsorption modulators based on GaAs-related materials." Licentiate thesis, KTH, Microelectronics and Information Technology, IMIT, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-292.
Повний текст джерелаGoubault, de Brugière Timothée. "Methods for optimizing the synthesis of quantum circuits Quantum CNOT Circuits Synthesis for NISQ Architectures Using the Syndrome Decoding Problem Quantum circuits synthesis using Householder transformations Synthesizing quantum circuits via numerical optimization Reuse method for quantum circuit synthesis." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASG018.
Повний текст джерелаTo run an abstract algorithm on a quantum computer, the algorithm must be compiled into a sequence of low-level instructions that can be executed by the processor. The compilation step is crucial because it determines the quantity of resources necessary for the execution of an algorithm. Therefore, the compilation stage must be optimized. In this thesis, we are interested in a brick of compilation: the synthesis of quantum circuits from an abstract specification of an operator.First, we study the case where the unitary matrix of a quantum operator is given to us and we explore the minimization of both quantum resources and classical resources. Even if the simultaneous optimization of these two types of resources seems difficult, we propose better compromises improving the literature.Secondly, we are interested in the class of so-called reversible linear operators. This time we are exclusively interested in the optimization of quantum resources and we improve the state of the art in various cases of quantum metrics (circuit size, circuit depth) and processors (NISQ, fully-connected processors)
Perdomo, Alejandro. "Designing and Probing Open Quantum Systems: Quantum Annealing, Excitonic Energy Transfer, and Nonlinear Fluorescence Spectroscopy." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10290.
Повний текст джерелаZhang, Huaijian. "Utilization of Symmetry in Optimization of Tensor Contraction Expressions." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1285047367.
Повний текст джерелаHörnedal, Niklas. "Generalizations of the Mandelstam-Tamm Quantum Speed Limit." Thesis, Stockholms universitet, Fysikum, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-193265.
Повний текст джерелаAbreu, Jean Faber Ferreira de. "Quantum games from biophysical Hamiltonians and a sub-neuronal optimization criterion of the information." Laboratório Nacional de Computação Científica, 2006. http://www.lncc.br/tdmc/tde_busca/arquivo.php?codArquivo=108.
Повний текст джерелаA Teoria de Jogos (TJs) é um formalismo matemático usado para analisar situações de conflitos entre duas ou mais partes. Nesses conflitos, cada parte possui um conjunto de ações (estratégias) que auxilia na otimização de seus objetivos. Os objetivos dos jogadres são as recompensas (payoffs) que cada um recebe de acordo com a estratégia adotada. Ao se quantizar um jogo, mostra-se ganhos em eficiência operacional e ganhos na estabilidade das soluções. Em um jogo quântico (JQ), as estratégias são operadores que atuam num sistema isolado. Uma questão natural é considerar um jogo num sistema aberto. Nesta situação as estratégias são trocadas por operadores de Kraus que representam uma medida natural do ambiente. Nosso interesse é encontrar as condições físicas necessáriaas para modelarmos um sistema quântico aberto como um jogo. Para analisar essa questão aplicamos o formalismo de Operações Quânticas (OQs) sobre o sistema de Fröhlich e o apresentamos como um modelo de JQ. A interpretação é um conflito entre diferentes configurações do ambiente que, ao inserirem ruído no sistema principal, exibem regiões de mínima perda de informação. O modelo de Fröhlich vem sendo usado para descrever a dinâmica biofísica dos microtúbulos neuronais. Ao estruturamos o modelo de Fröhlich nos JQs, mostramos que as regiões de estabilidade podem existir sob condições fisiológicas. Usando o aspecto evolucionista, a TJs pode ser a chave para a descrição de processos de otimização da informação em nível sub-neuronal.
Lee, Sangjin Ph D. Massachusetts Institute of Technology. "Design and optimization of colloidal quantum dot solids for enhanced charge transport and photovoltaics." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104152.
Повний текст джерелаThis 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 93-102).
Colloidal quantum dots (CQDs) have attracted much attention due to their distinctive optical properties such as wide spectral responses and tunable absorption spectra with simple size control. These properties, together with the advantages of solution processing and superior robustness to organic materials, have motivated the recent investigation of CQD-based solar cells, which have seen rapid growth in power conversion efficiency in just the last 10 years, to a current record of over 10%. However, in order to continue to push the efficiencies higher, a better understanding of the charge transport phenomena in CQD films is needed. While the carrier transport mechanisms between isolated molecules have been explored theoretically and the device-scale mobility of CQD layers has been characterized using experimental measurements such as time-of-flight analysis and field-effect-transistor measurements, a systematic study of the connection between these two distinct scales is required in order to provide crucial information regarding how CQD layers with higher charge carrier mobility can be achieved. While a few strategies such as ligand exchanges, band-like transport, and trap-state-mediated transport have been suggested to enhance the charge carrier mobility, inhomogeneity in CQD solids has been considered a source of the mobility degradation because the electronic properties in individual CQDs may have dispersions introduced in the synthesis and/or in the deposition process, leading to the deviations of the localized energy states from the regular positions or the average energy levels. Here, we suggest that control over such design factors in CQD solids can provide important pathways for improvements in device efficiencies as well as the charge carrier mobility. In particular, we have focused on the polydispersity in CQDs, which normally lies in the range of 5-15%. The effect of size-dispersion in CQD solids on the charge carrier mobility was computed using charge hopping transport models. The experimental film deposition processes were replicated using a molecular dynamics simulation where the equilibrium positions of CQDs with a given radii distribution were determined under a granular potential. The radii and positions of the CQDs were then used in the charge hopping transport simulator where the carrier mobility was estimated. We observed large decreases (up to 70%) in electron mobility for typical experimental polydispersity (about 10%) in CQD films. These large degradations in hopping charge transport were investigated using transport vector analysis with which we suggested that the site energy differences raised the portion of the off-axis rate of charge transport to the electric field direction. Furthermore, we have shown that controlling the size distribution remarkably impacts the charge carrier mobility and we suggested that tailored and potentially experimentally achievable re-arrangement of the CQD size ensemble can mediate the mobility drops even in highly dispersive cases, and presents an avenue towards improved charge transport. We then studied the degradation in CQD solar cells with respect to the polydispersity and how these enhanced charge transport from re-design of CQD solids can boost the photovoltaic performances. In addition, we estimated the potential in the binary CQD solids in terms of their improved charge transport and efficient light absorption. Combined with the accurate size-dependent optical absorption model for CQDs, our hopping model confirmed that the inclusion of smaller CQDs could enhance both the charge transport and the solar light absorption, leading to the enhanced average charge generation rates and solar cell performance.
by Sangjin Lee.
Ph. D.
Malmberg, Olle, and Joakim Wellenstam. "Quantum Portfolio Optimization : a Multi-Level Perspective Study of the Swedish Fund Management Industry." Thesis, KTH, Industriell ekonomi och organisation (Inst.), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-296676.
Повний текст джерелаUnder de senaste åren har kvantdatorer uppnått nya nivåer av sofistikation och är enligt vissa uppskattningar bara några år från att användas i produktion. Alltmer litteratur pekar ut potentiella användningsområden inom olika branscher och finansbranschen har identifierats som ett område med särskilt stor potential. En applikation som nyligen sett experimentell framgång är 'Quantum Portfolio Optimization' (QPO), där forskare framgångsrikt har översatt och beräknat optimeringsuppgiften på existerande kvantdatorer. Eftersom klassiska portföljoptimeringsalgoritmer ofta är krävande i datorkraft så kan kvantdatorers snabbhet potentiellt ge stora fördelar för olika intressenter. En bransch som använder portföljoptimering är fondförvaltning. Med tanke på den mångfald som finns bland fonder, med avseende på strategi och metoder, är det troligt att sociologiska faktorer spelar en roll i valet av vilka tekniska lösningar som används. Samspelet mellan sociologiska och tekniska faktorer kommer att vara centralt i denna studie, då den ämnar undersöka villkoren förutsättningarna för QPO inom svenska fondindustrin genom ett sociotekniskt perspektiv. Först genomförs halvstrukturerade kvalitativa intervjuer med branschaktörer och kvantdatoraktörer. Detta följs av en tematisk analys i två steg, strukturerad efter de sociotekniska dimensionerna i Geels 'Multi-Level Perspective' (MLP). Baserat på kodning av uttalanden så skapas fyra nyckelteman för att beskriva branschens egenskaper. Sedan analyseras dessa teman tillsammans med nischen, QPO, utifrån perspektiv från systeminnovationsteorier för att utvärdera QPO:s beredskap och dess potentiella sociotekniska effekter på branschen. De viktigaste resultaten som kännetecknar fondindustrin sammanfattas genom fyra teman. I synnerhet är avvägningen mellan kvantitativa och kvalitativa metoder, bristfälligheten i historiska data, betydelsen av tredjepartsleverantörer och det dåligt fungerande och styva konkurrenslandskapet viktiga egenskaper. Det nuvarande läget för QPO anses inte ha nått en kommersiellt lönsam nivå sett till förhållandet mellan pris och prestanda, men nischen har byggt ett starkt stödnätverk som kommer hjälpa den att förbättras över tid. Dessutom pekar resultaten mot att nischteknologin QPO kommer att introduceras i begränsad utsträckning, men kan med tiden ändå komma att orsaka betydande störningar eftersom den bidrar till att omforma branschens socio-tekniska arkitektur.
Fišer, Petr. "Simplification of quantum circuits for modular exponentiation." Master's thesis, Vysoká škola ekonomická v Praze, 2015. http://www.nusl.cz/ntk/nusl-261826.
Повний текст джерелаCorn, John Russell. "Optimization Problems in Hilbert Space with POSS Complexes." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/1381.
Повний текст джерелаNi, Xiaotong Verfasser], J. I. [Gutachter] [Akademischer Betreuer] [Cirac, and Alejandro [Gutachter] Ibarra. "Quantum memory: design and optimization / Xiaotong Ni ; Gutachter: Ignacio Cirac, Alejandro Ibarra ; Betreuer: Ignacio Cirac." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1128309939/34.
Повний текст джерелаBurger, Anat. "Optimization of a microwave resonator cavity to perform electron spin resonance measurements on quantum dots." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36131.
Повний текст джерелаIncludes bibliographical references (p. 51).
This thesis attempts to improve on an ongoing experiment of detecting electron spin resonance (ESR) on AlGaAs/GaAs lateral quantum dots. The experiment is performed in a 2.5 Tesla magnetic field at temperatures around 100mK. A resonator cavity is used to expose the quantum dot to a perturbational microwave magnetic field pulse that induces electron spin flip transitions. The statistics for measuring the probabilities of these transitions can be improved by increasing the strength and/or the duration of the pulsed magnetic field. The drawback is that both of these improvements lead to thermal heating which diminishes the quantum nature of the dot. I used electromagnetic field calculations and simulation software to explore different resonant modes, geometries, materials, and methods of excitation and optimize the design of potential new cavities. Two cavities were built specifically to test the TM010 and TE011 cylindrical modes. Although they did not perform as well as was theoretically expected, these cavities provide a better magnetic field magnitude per heating power than the current cavity.
by Anat Burger.
S.B.
Simnacher, Timo Yannick [Verfasser], and Otfried [Gutachter] Gühne. "The interplay between quantum entanglement, coherence, and convex optimization / Timo Yannick Simnacher ; Gutachter: Otfried Gühne." Siegen : Universitätsbibliothek der Universität Siegen, 2021. http://nbn-resolving.de/urn:nbn:de:hbz:467-19677.
Повний текст джерелаZhang, Zhenzhong. "Epitaxial growth optimization for 1.3-um InGaAs/GaAs Vertical-Cavity Surface-Emitting lasers." Licentiate thesis, KTH, Microelectronics and Applied Physics, MAP, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4648.
Повний текст джерелаLong-wavelength (1.3-μm) vertical-cavity surface-emitting lasers (VCSELs) are of great interest as low-cost, high performance light sources for fiber-optic metro and access networks. During recent years the main development effort in this field has been directed towards all epitaxial GaAs-based structures by employing novel active materials. Different active region candidates for GaAs-based 1.3-μm VCSELs such as GaInNAs/GaAs QWs, GaAsSb QWs or InAs/InGaAs QDs have been investigated. However, the difficult growth and materials properties of these systems have so far hampered any real deployment of the technology. More recently, a new variety of VCSELs have been developed at KTH as based on highly strained InGaAs QWs and negative gain cavity detuning to reach the 1.3-μm wavelength window. The great benefit of this approach is that it is fully compatible with standard materials and processing methods.
The aim of this thesis is to investigate long-wavelength (1.3-μm) VCSELs using ~1.2-μm In0.4GaAs/GaAs Multiple Quantum Wells (MQWs). A series of QW structures, DBR structures and laser structures, including VCSELs and Broad Area lasers (BALs) were grown by metal-organic vapor phase epitaxy (MOVPE) and characterized by various techniques: Photoluminescence (PL), high-resolution x-ray diffraction (XRD), atomic force microscopy (AFM), high accuracy reflectance measurements as well as static and dynamic device characterization. The work can be divided into three parts. The first part is dedicated to the optimization and characterization of InGaAs/GaAs QWs growth for long wavelength and strong luminescence. A strong sensitivity to the detailed growth conditions, such as V/III ratio and substrate misorientation is noted. Dislocations in highly strained InGaAs QW structure and Sb as surfactant assisted in InGaAs QW growth are also discussed here. The second part is related to the AlGaAs/GaAs DBR structures. It is shown that the InGaAs VCSELs with doped bottom DBRs have significantly lower slope efficiency, output power and higher threshold current. By a direct study of buried AlGaAs/GaAs interfaces, this is suggested to be due to doping-enhanced Al-Ga hetero-interdiffusion. In the third part, singlemode, high-performance 1.3-μm VCSELs based on highly strained InGaAs QWs are demonstrated. Temperature stable singlemode performance, including mW-range output power and 10 Gbps data transmission, is obtained by an inverted surface relief technique.
Garduno, Nolasco Edson. "Nano-scale approaches for the development and optimization of state-of-the-art semiconductor photovoltaic devices." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/nanoscale-approaches-for-the-development-and-optimization-of-stateoftheart-semiconductor-photovoltaic-devices(927e70db-03ff-43e0-8b27-5472bc4a293f).html.
Повний текст джерелаOlofsson, Karl-Johan. "Black-box optimization of simulated light extraction efficiency from quantum dots in pyramidal gallium nitride structures." Thesis, Linköpings universitet, Matematiska institutionen, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-162235.
Повний текст джерелаReimpell, Michael. "Quantum information and convex optimization /." 2008. http://www.gbv.de/dms/bs/toc/559790392.pdf.
Повний текст джерелаSikora, Jamie William Jonathon. "Applications of Semidefinite Programming in Quantum Cryptography." Thesis, 2007. http://hdl.handle.net/10012/3056.
Повний текст джерелаMattingly, Alan Charles. "'Variational' optimization in quantum field theory." Thesis, 1993. http://hdl.handle.net/1911/16649.
Повний текст джерелаPye, Cory Christopher. "Applications of optimization to quantum chemistry /." 1997.
Знайти повний текст джерелаSilva, Hugo Gonçalves. "Quantum Effects for Spintronic Devices Optimization." Doctoral thesis, 2010. http://hdl.handle.net/10174/2242.
Повний текст джерелаAmy, Matthew. "Algorithms for the Optimization of Quantum Circuits." Thesis, 2013. http://hdl.handle.net/10012/7818.
Повний текст джерелаRao, M. V. Panduranga. "Bounds On Augmented Automata And Quantum Adiabatic Optimization." Thesis, 2007. http://hdl.handle.net/2005/518.
Повний текст джерелаSikora, Jamie. "Analyzing Quantum Cryptographic Protocols Using Optimization Techniques." Thesis, 2012. http://hdl.handle.net/10012/6760.
Повний текст джерелаPaetznick, Adam. "Resource optimization for fault-tolerant quantum computing." Thesis, 2013. http://hdl.handle.net/10012/8111.
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