Log in

Relevant bibliographies by topics / Quantum spin models / Dissertations / Theses

To see the other types of publications on this topic, follow the link: Quantum spin models.

Dissertations / Theses on the topic 'Quantum spin models'

Author: Grafiati

Published: 4 June 2021

Last updated: 3 February 2022

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 dissertations / theses for your research on the topic 'Quantum spin models.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.

1

Oriti, Daniele. "Spin foam models of quantum spacetime." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620008.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Collins, Alexander Rory Physics Faculty of Science UNSW. "Quantum lattice models." Publisher:University of New South Wales. Physics, 2008. http://handle.unsw.edu.au/1959.4/43408.

Full text

Abstract:

This thesis presents studies of the low energy properties of nseveral frustrated spin-1/2 Heisenberg antiferromagnets using various analytic and computational methods. The models studied include the union jack model, the alternating Heisenberg chain, the Heisenberg bilayer model, and the spin-Peierls model. The union jack model is a Heisenberg antiferromagnetic spin model with frustration, and is analyzed using spin-wave theory. For small values of the frustrating coupling $\alpha$, the system is N{\' e}el ordered, while for large $\alpha$ the frustration is found to induce a canted phase. Spi

APA, Harvard, Vancouver, ISO, and other styles

3

Dowdall, R. J. "Spin foam models for 3D quantum geometry." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/11755/.

Full text

Abstract:

Various aspects of three-dimensional spin foam models for quantum gravity are discussed. Spin foam models and graphical calculus are introduced via the Ponzano-Regge model for 3d gravity and some important properties of this model are described. The asymptotic formula for the 6j symbol found by Ponzano and Regge is generalised to include the Ponzano-Regge amplitude for triangulations of handlebodies. Some simple observables are computed in a model for fermions coupled to 3d gravity. The result is a sum over spin foam models with certain vertex amplitudes which are described. An explicit exampl

APA, Harvard, Vancouver, ISO, and other styles

4

Murgan, Rajan. "Bethe Ansatz and Open Spin-1/2 XXZ Quantum Spin Chain." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/69.

Full text

Abstract:

The open spin-1/2 XXZ quantum spin chain with general integrable boundary terms is a fundamental integrable model. Finding a Bethe Ansatz solution for this model has been a subject of intensive research for many years. Such solutions for other simpler spin chain models have been shown to be essential for calculating various physical quantities, e.g., spectrum, scattering amplitudes, finite size corrections, anomalous dimensions of certain field operators in gauge field theories, etc. The first part of this dissertation focuses on Bethe Ansatz solutions for open spin chains with nondiagonal bo

APA, Harvard, Vancouver, ISO, and other styles

5

Liu, Chen. "Variational methods and their applications to frustrated quantum spin models." Thesis, Boston University, 2012. https://hdl.handle.net/2144/32030.

Full text

Abstract:

Thesis (Ph.D.)--Boston University<br>PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.<br>Quantum spin models are useful in many areas of physics, such as strongly correlated materials and quantum phase transitions, or, generally, quantum many-body systems. Most of the models of interest are not a

APA, Harvard, Vancouver, ISO, and other styles

6

Harada, Kenji. "Numerical Study of Quantum Spin Models by Loop Algorithm." Kyoto University, 1998. http://hdl.handle.net/2433/77874.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Nicotra, Alessandro. "Analytical map between EPRL spin foam models in loop quantum gravity." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23179/.

Full text

Abstract:

Loop Quantum Gravity (LQG) is one of the theoretical frameworks attempting to build a quantum theory of gravitation. Spin Foam theory provides a regularized, background-independent, and Lorentz covariant path integral for the transition amplitudes between LQG kinematical states. The state of the art of the theory is the EPRL model, formulated with the Euclidean and the Lorentzian signatures. They differ by their gauge group structures, which are respectively SO(4,R) and SO(1,3). The first is a compact group: it has finite-dimensional unitary irreducible representations, and the integral on

APA, Harvard, Vancouver, ISO, and other styles

8

Shevchenko, Pavel Physics Faculty of Science UNSW. "Quantum Phenomena in Strongly Correlated Electrons Systems." Awarded by:University of New South Wales. Physics, 1999. http://handle.unsw.edu.au/1959.4/32669.

Full text

Abstract:

Quantum phenomena in high-Tc superconductors and dimerized quantum Heisenberg antiferromagnets are studied analytically in this thesis. The implications of the Fermi surface consisting of the disjoint pieces, observed in cuprate superconductors, are considered. It is demonstrated that in this case the g-wave superconducting pairing is closely related to d-wave pairing. The superconductivity in this system can be described in terms of two almost degenerate superconducting condensates. As a result a new spatial scale lg, much larger than the superconducting correlation length x, arises and a

APA, Harvard, Vancouver, ISO, and other styles

9

Sarno, Giorgio. "A numerical approach to spin foam models of quantum gravity." Thesis, Aix-Marseille, 2020. http://www.theses.fr/2020AIXM0231.

Full text

Abstract:

Les modèles de mousse de spin proposent une définition covariante de Lorentz de la dynamique de la gravité quantique en boucle.C'est une approche non-perturbative qui a déjà obtenu un résultat important, reproduire la Relativité Générale discrétisée dans une limite semi-classique. Cependant, la complexité analytique des modèles est telle que des questions clés concernant leur cohérence théorique et leurs prédictions physiques restent ouvertes. Dans cette thèse, j'introduis un cadre systématique pour effectuer des calculs numériques dans ce domaine. La thèse contient une introduction aux théori

APA, Harvard, Vancouver, ISO, and other styles

10

Erbe, Björn [Verfasser], and John [Akademischer Betreuer] Schliemann. "Central spin models: Quantum integrability and hyperfine induced spin dynamics / Björn Erbe. Betreuer: John Schliemann." Regensburg : Universitätsbibliothek Regensburg, 2011. http://d-nb.info/1022820346/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Foxon, Tim. "Discrete models for quantum gravity in three dimensions." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338071.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Leseleuc, de kerouara Sylvain de. "Quantum simulation of spin models with assembled arrays of Rydberg atoms." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLO007.

Full text

Abstract:

Des atomes individuels piégés dans des matrices de pinces optiques et excités vers des états de Rydberg forment une plateforme expérimentale prometteuse pour la simulation quantique de modèles de spins. Lors de cette thèse, nous avons d’abord résolu le problème du chargement aléatoire des pièges, seulement 50 % d’entre eux étant chargés avec un atome. Nous avons développé une technique pour préparer des matrices 2D, puis 3D, d’atomes de 87Rb en les déplaçant un par un avec une pince optique mobile contrôlée par ordinateur. Nous avons ensuite réalisé le modèle d’Ising en excitant de manière coh

APA, Harvard, Vancouver, ISO, and other styles

13

Rowlands, Daniel Alexander. "Spectral and dynamical properties of disordered and noisy quantum spin models." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/284393.

Full text

Abstract:

This thesis, divided into two parts, is concerned with the analysis of spectral and dynamical characteristics of certain quantum spin systems in the presence of either I) quenched disorder, or II) dynamical noise. In the first part, the quantum random energy model (QREM), a mean-field spin glass model with a many-body localisation transition, is studied. In Chapter 2, we attempt a diagrammatic perturbative analysis of the QREM from the ergodic side, proceeding by analogy to the single-particle theory of weak localisation. Whilst we are able to describe diffusion, the analogy breaks down and a

APA, Harvard, Vancouver, ISO, and other styles

14

Dimitrova, Ivana Ljubomirova. "Realizing quantum spin models with ⁷Li atoms in an optical lattice." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/128327.

Full text

Abstract:

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, February, 2020<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 279-292).<br>Quantum spin Hamiltonians are paradigmatic models, which display different kinds of quantum phase transitions, strongly-correlated and topological ground states, and various regimes of transport. Expanding their significance, many mappings exist between quantum spin models and other systems in different areas of physics, mathematics, and beyond. Even though quantum spin models have been studied extensive

APA, Harvard, Vancouver, ISO, and other styles

15

Grosse, Harald, Karl-Georg Schlesinger, and grosse@doppler thp univie ac at. "A Suggestion for an Integrability Notion for Two Dimensional Spin." ESI preprints, 2001. ftp://ftp.esi.ac.at/pub/Preprints/esi1015.ps.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Goomanee, Salvish. "Rigorous Approach to Quantum Integrable Models at Finite Temperature." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEN039/document.

Full text

Abstract:

Cette thèse développe un cadre rigoureux qui permet de démontrer des représentations exactes associées à divers observables de la chaîne XXZ de Heisenberg de spin 1/2 à température finie. Il a était argumenté dans la littérature que l’énergie libre par site ou les longueurs de corrélations admettent des représentations intégrales où les intégrandes sont exprimées en termes de solutions d’équations intégrales non-linéaires. Les dérivations de ces représentations reposaient sur divers conjectures telles que l’existence d’une valeur propre de la matrice de transfert quantique, real, non-dégénérée

APA, Harvard, Vancouver, ISO, and other styles

17

Flynn, James S. "A study of two quantum spin models on the body-centred cubic lattice." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0028/MQ36440.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Davis, Alexander Michael. "Supersymmetry Method for Network Models of Quantum Hall Transitions and Hybrid Structures." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1566157715556164.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Gergs, Anne Cornelie Verfasser], Stefan [Akademischer Betreuer] [Weßel, and Riccardo [Akademischer Betreuer] Mazzarello. "Effective quantum spin models for graphene nanoribbons / Anne Cornelie Gergs ; Stefan Weßel, Riccardo Mazzarello." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1171906838/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Gergs, Anne Cornelie [Verfasser], Stefan [Akademischer Betreuer] Weßel, and Riccardo [Akademischer Betreuer] Mazzarello. "Effective quantum spin models for graphene nanoribbons / Anne Cornelie Gergs ; Stefan Weßel, Riccardo Mazzarello." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1171906838/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Exler, Matthias. "On classical and quantum mechanical energy spectra of finite Heisenberg spin systems." Doctoral thesis, [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980110440.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Juozapavicius, Ausrius. "Density-Matrix Renormalization-Group Analysis of Kondo and XY models." Doctoral thesis, KTH, Physics, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3260.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Schober, Giulio Albert Heinrich [Verfasser], and Manfred [Akademischer Betreuer] Salmhofer. "Quantum Field Theory of Material Properties: Its Application to Models of Rashba Spin Splitting / Giulio Albert Heinrich Schober ; Betreuer: Manfred Salmhofer." Heidelberg : Universitätsbibliothek Heidelberg, 2016. http://d-nb.info/1180738195/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Bidzhiev, Kemal. "Out-of-equilibrium dynamics in a quantum impurity model." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS352/document.

Full text

Abstract:

Le domaine des problèmes quantiques à N-corps à l'équilibre et hors d'équilibre sont des sujets majeurs de la Physique et de la Physique de la matière condensée en particulier. Les propriétés d'équilibre de nombreux systèmes unidimensionnels en interaction sont bien comprises d'un point de vue théorique, des chaînes de spins aux théories quantiques des champs dans le continue. Ces progrès ont été rendus possibles par le développement de nombreuses techniques puissantes, comme, par exemple, l'ansatz de Bethe, le groupe de renormalisation, la bosonisation, les états produits de matrices ou la th

APA, Harvard, Vancouver, ISO, and other styles

25

Bondesan, Roberto. "Edge states and supersymmetric sigma models." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00808736.

Full text

Abstract:

Une propriété fondamentale de l'effet Hall quantique est la présence des états de bord. Ils résistent á la localisation et sont responsables de la quantification parfaite de la conductance de Hall. La transition entre les plateaux d'effet Hall quantique entier est une transition de délocalisation, qui peut être identifiée comme un point fixe de couplage fort d'un modèle sigma supersymétrique en 1+1-dimensions avec terme topologique theta. La théorie conforme décrivant cette transition présente des caractéristiques inhabituelles telles que la non-unitarité, et a résisté á toute tentative de rés

APA, Harvard, Vancouver, ISO, and other styles

26

Schäpers, Markus. "Exploring the Frustrated Spin-Chain Compound Linarite by NMR and Thermodynamic Investigations." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-153947.

Full text

Abstract:

Within the last decades low-dimensional frustrated quantum spin systems have attracted great interest in the field of modern research. In these systems a competition of various magnetic interactions takes place, leading to an energetically degenerated magnetic ground state, and thus to the occurrence of exotic, unconventional physical properties at low temperatures. This thesis focuses on the quasi one-dimensional frustrated spin chain system linarite, PbCuSO4(OH)2. In this compound the basic building blocks are CuO4 plaquettes which are connected to each other along one crystallographic dire

APA, Harvard, Vancouver, ISO, and other styles

27

Tschirhart, Hugo. "From two Algebraic Bethe Ansätze to the dynamics of Dicke-Jaynes-Cummings-Gaudin quantum integrable models through eigenvalue-based determinants." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0098/document.

Full text

Abstract:

Le travail présenté dans cette thèse est inspiré de précédents résultats sur les modèles de Gaudin ne contenant que des spins-1/2 (ces modèles sont intégrables) qui, par un changement de variable dans les équations de Bethe algébriques, parviennent à simplifier le traitement numérique de ces modèles. Cette optimisation numérique s'effectue par l'intermédiaire d'une construction en déterminant, ne dépendant que des variables précédemment mentionnées, pour chaque produit scalaire intervenant dans l'expression de la moyenne d'une observable à un temps donné. En montrant qu'il est possible d'utili

APA, Harvard, Vancouver, ISO, and other styles

28

Stephan, Jean-Marie. "Intrication dans des systèmes quantiques à basse dimension." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112308.

Full text

Abstract:

On a compris ces dernières années que certaines mesures d'intrications sont un outil efficace pour la compréhension et la caractérisation de phases nouvelles et exotiques de la matière, en particulier lorsque les méthodes traditionnelles basées sur l'identification d'un paramètre d'ordre sont insuffisantes. Cette thèse porte sur l'étude de quelques systèmes quantiques à basse dimension où un telle approche s'avère fructueuse. Parmi ces mesures, l'entropie d'intrication, définie via une bipartition du système quantique, est probablement la plus populaire, surtout à une dimension. Celle-ci est h

APA, Harvard, Vancouver, ISO, and other styles

29

Joshi, Darshan Gajanan. "Magnetic quantum phase transitions: 1/d expansion, bond-operator theory, and coupled-dimer magnets." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-198634.

Full text

Abstract:

In the study of strongly interacting condensed-matter systems controlled microscopic theories hold a key position. Spin-wave theory, large-N expansion, and $epsilon$-expansion are some of the few successful cornerstones. In this doctoral thesis work, we have developed a novel large-$d$ expansion method, $d$ being the spatial dimension, to study model Hamiltonians hosting a quantum phase transition between a paramagnet and a magnetically ordered phase. A highlight of this technique is that it can consistently describe the entire phase diagram of the above mentioned models, including the quantum

APA, Harvard, Vancouver, ISO, and other styles

30

Carrozza, Sylvain. "Tensorial methods and renormalization in Group Field Theories." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112147/document.

Full text

Abstract:

Cette thèse présente une étude détaillée de la structure de théories appelées GFT ("Group Field Theory" en anglais),à travers le prisme de la renormalisation. Ce sont des théories des champs issues de divers travaux en gravité quantique, parmi lesquels la gravité quantique à boucles et les modèles de matrices ou de tenseurs. Elles sont interprétées comme desmodèles d'espaces-temps quantiques, dans le sens où elles génèrent des amplitudes de Feynman indexées par des triangulations,qui interpolent les états spatiaux de la gravité quantique à boucles. Afin d'établir ces modèles comme des théories

APA, Harvard, Vancouver, ISO, and other styles

31

Chakhmakhchyan, Levon. "Entangled states and coherent interaction in resonant media." Thesis, Dijon, 2014. http://www.theses.fr/2014DIJOS026/document.

Full text

Abstract:

Nous analysons les caractéristiques d'intrication de quelques matériaux à l'état solide ainsi que des systèmes particuliers d'atomes et de champs en interaction. Une étude détaillée de la riche structure de phase des modèles de spins de basse dimension, décrivant le minéral naturel d'azurite et les composés de coordination à base de cuivre, a révélé des régimes à comportement d'intrication des plus robustes. En utilisant l'approche des systèmes dynamiques, la structure de phase de certains modèles classiques en réseaux hiérarchiques (récursifs) a aussi été étudiée et, pour la première fois, la

APA, Harvard, Vancouver, ISO, and other styles

32

Liu, Yi. "Dynamics, Synchronization and Spin Squeezing in a Two-Spin Model." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112216.

Full text

Abstract:

Cette thèse se concentre sur la dynamique d'un système atomique froid qui se composede deux états internes d'atomes piégés dans un potentiel magnétique . La motivation decette thèse est une série d'expériences sur ce système réalisées en 2010, où un grandtemps de cohérence surprenante entre les deux états internes ont été observés. Cephénomène a été expliqué par la théorie cinétique qui a utilisé une approche de champmoyen. Dans cette thèse, nous essayons d'utiliser une approche différente et étudier leseffets de corrélations quantiques dans la dynamique du système. De plus, nous sommeségaleme

APA, Harvard, Vancouver, ISO, and other styles

33

Meier, Hannes. "Phase transitions in novel superfluids and systems with correlated disorder." Doctoral thesis, KTH, Statistisk fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-160929.

Full text

Abstract:

Condensed matter systems undergoing phase transitions rarely allow exact solutions. The presence of disorder renders the situation even worse but collective Monte Carlo methods and parallel algorithms allow numerical descriptions. This thesis considers classical phase transitions in disordered spin systems in general and in effective models of superfluids with disorder and novel interactions in particular. Quantum phase transitions are considered via a quantum to classical mapping. Central questions are if the presence of defects changes universal properties and what qualitative implications

APA, Harvard, Vancouver, ISO, and other styles

34

Asghar, Zahid Bin. "Quantum spin structures and phase separation in the Hubbard model." Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/34512.

Full text

Abstract:

In this thesis we focus on a systematic study of the ground state of the one-dimensional one-band Hubbard model in the Hartree–Fock approximation. Phases with non-uniform charge density and states with coexisting phases separated by a domain wall are included in the study. We calculate the full Hartree–Fock phase diagram for uniform and non-uniform phases, and we show that at particular electron densities the uniform phase is unstable to phase separation. Supercell calculations are carried out, and we use the computational minimisation procedure to calculate the Hartree–Fock energies for the s

APA, Harvard, Vancouver, ISO, and other styles

35

Vernier, Eric. "Non compact conformal field theories in statistical mechanics." Thesis, Paris, Ecole normale supérieure, 2015. http://www.theses.fr/2015ENSU0005/document.

Full text

Abstract:

Les comportements critiques des systèmes de mécanique statistique en 2 dimensions ou de mécanique quantique en 1+1 dimensions, ainsi que certains aspects des systèmes sans interactions en 2+1 dimensions, sont efficacement décrits par les méthodes de la théorie des champs conforme et de l'intégrabilité, dont le développement a été spectaculaire au cours des 40 dernières années. Plusieurs problèmes résistent cependant toujours à une compréhension exacte, parmi lesquels celui de la transition entre plateaux dans l'Effet Hall Quantique Entier. La raison principale en est que de tels problèmes sont

APA, Harvard, Vancouver, ISO, and other styles

36

Lienhard, Vincent. "Physique quantique expérimentale à N corps dans des matrices d'atomes de Rydberg. Des modèles de spins à la matière topologique." Thesis, Université Paris-Saclay (ComUE), 2019. https://pastel.archives-ouvertes.fr/tel-02949007.

Full text

Abstract:

Des atomes individuels piégés dans des matrices de pinces optiques et excités vers des états de Rydberg forment une plateforme expérimentale performante pour la simulation quantique de problèmes à N corps, comme le confirment les récents progrès dans le domaine. Lors de cette thèse, nous avons d’abord montré la production de matrices de pinces optiques, toutes chargées par des atomes uniques dans leur état fondamental. Notre technique de piégeage a été étendue au cas des atomes de Rydberg. Ces derniers sont chassés des zones de haute intensité par la force pondéromotrice. Par conséquent, nous

APA, Harvard, Vancouver, ISO, and other styles

37

Rosa, Priscila Ferrari Silveira 1988. "Dinâmica quântica de estados de impurezas em cadeias de spin." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277877.

Full text

Abstract:

Orientador: Guillermo Gerardo Cabrera Oyarzún<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física "Gleb Wataghin"<br>Made available in DSpace on 2018-08-16T15:57:09Z (GMT). No. of bitstreams: 1 Rosa_PriscilaFerrariSilveira_M.pdf: 3441309 bytes, checksum: ac0fe3faa7642e9a7ef8330049e33761 (MD5) Previous issue date: 2010<br>Resumo: A descrição da dinâmica quântica de sistemas de muitos corpos é um ingrediente chave para a computação quântica. No presente projeto, propomos o estudo da dinâmica em cadeias finitas de spin 1/2 na presença de impurezas ou defeitos. O m

APA, Harvard, Vancouver, ISO, and other styles

38

Schossler, Matheus de Oliveira. "Dinâmica de operadores de dois spins no modelo XX." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-15092017-090718/.

Full text

Abstract:

Propriedades dinâmicas de sistemas quânticos de muitos corpos é um tópico de grande interesse em física da matéria condensada. Estas propriedades nos dão informação sobre a propagação de excitações elementares e de mecanismos de relaxação em sistemas interagentes. Neste contexto, as funções de correlação tem se tornado ainda mais relevantes devido a experimentos em sistemas de átomos frios e íons armadilhados que medem diretamente no domínio temporal os comportamentos assintóticos no tempo. No entanto, até o momento a maioria dos estudos em cadeias de spin quânticas focaram-se em correlações d

APA, Harvard, Vancouver, ISO, and other styles

39

Halász, Gábor B. "Doping a topological quantum spin liquid : slow holes in the Kitaev honeycomb model." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:928ba58d-c69c-4e85-8d49-677d7e9c0fdc.

Full text

Abstract:

We present a controlled microscopic study of hole dynamics in both a gapped and a gapless quantum spin liquid. Our approach is complementary to previous phenomenological works on lightly doped quantum spin liquids as we introduce mobile holes into the ground state of the exactly solvable Kitaev honeycomb model. In the spatially anisotropic (Abelian) gapped phase of the model, we address the properties of a single hole [its internal degrees of freedom as well as its hopping properties], a pair of holes [their absolute and relative particle statistics as well as their interactions], and the coll

APA, Harvard, Vancouver, ISO, and other styles

40

Medeiros, Marcos Henrique Lima de. "Propagação de excitações de carga e spin em isolantes topológicos 2D." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-11102017-132437/.

Full text

Abstract:

Neste trabalho, nossa principal motivação foi o entendimento da dinâmica de pacotes de onda em isolantes topológicos 2D. Como excitações de carga se movem nesses materiais? De que maneira essas trajetórias dependem das condições iniciais, e de que forma as condições de contorno influenciam nessa dinâmica? Essas foram algumas das perguntas que guiaram nosso trabalho. Através de simulações computacionais, estudamos o movimento de pacotes de onda gaussianos em poços quânticos de HgTe/CdTe. O comportamento de isolante topológico para essa heteroestrutura foi prevista teoricamente no importante tr

APA, Harvard, Vancouver, ISO, and other styles

41

Collet, François. "Short scale study of 4-simplex assembly with curvature, in euclidean Loop Quantum Gravity." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4076/document.

Full text

Abstract:

Une étude d'un assemblage symétrique de trois 4-simplex en géométrie classique, de Regge et quantique. Nous étudions les propriétés géométriques et surtout la présence de courbure. Nous montrons que les géométries classique et de Regge de l'assemblage ont une courbure qui évolue en fonction de ses paramètres de bordure. Pour la géométrie quantique, une version euclidienne du modèle EPRL est utilisé avec une valeur pratique du paramètre Barbero-Immirzi pour définir l'amplitude de transition de l'ensemble et de ses composants. Un code C ++ est conçu pour calculer les amplitudes et étudier numéri

APA, Harvard, Vancouver, ISO, and other styles

42

Chagas, Emiliano Augusto. "Quebra de simetria e transição de fase quântica em alguns modelos de acoplamento spin-boson." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278181.

Full text

Abstract:

Orientador: Kyoko Furuya<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin<br>Made available in DSpace on 2018-08-10T14:44:05Z (GMT). No. of bitstreams: 1 Chagas_EmilianoAugusto_M.pdf: 5122954 bytes, checksum: a280b293a78cd819e62e73692ae4b99f (MD5) Previous issue date: 2008<br>Resumo: Neste trabalho estudamos o efeito sobre a Transição de Fase Quântica (TFQ) do Modelo de Dicke Integrável devido a adição de um pequeno termo (fixo) de interação de dois bósons na Aproximação de Onda Girante (RWA). Mostramos que, embora a descontinuidade na derivada

APA, Harvard, Vancouver, ISO, and other styles

43

Fuchs, Moritz Jakob [Verfasser], Björn [Gutachter] Trauzettel, and Haye [Gutachter] Hinrichsen. "Spin dynamics in the central spin model: Application to graphene quantum dots / Moritz Jakob Fuchs. Gutachter: Björn Trauzettel ; Haye Hinrichsen." Würzburg : Universität Würzburg, 2016. http://d-nb.info/1112041400/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Goldstein, Garry. "Applications of Many Body Dynamics of Solid State Systems to Quantum Metrology and Computation." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10555.

Full text

Abstract:

This thesis describes aspects of dynamics of solid state systems which are relevant to quantum metrology and computation. It may be divided into three research directions (parts). For the first part, a new method to enhance precision measurements that makes use of a sensor’s environment to amplify its response to weak external perturbations is described. In this method a “central” spin is used to sense the dynamics of surrounding spins, which are affected by the external perturbations that are being measured. The enhancement in precision is determined by the number of spins that are coupled st

APA, Harvard, Vancouver, ISO, and other styles

45

Shinjo, Kazuya. "Density-matrix renormalization group study of quantum spin systems with Kitaev-type anisotropic interaction." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215292.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Skinner, Andrew J. "Hydrogenic spin quantum computing in silicon and damping and diffusion in a chain-boson model." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3887.

Full text

Abstract:

Thesis (Ph. D.)--University of Maryland, College Park, 2006.<br>Thesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

APA, Harvard, Vancouver, ISO, and other styles

47

Penteado, Poliana Heiffig. "Transport through leaked Majorana modes in quantum dots and adatoms." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-13012014-135024/.

Full text

Abstract:

We investigate quantum resonant transport in two different systems: (i) a ferromagnetic Scanning Tunneling Microscope (STM) tip coupled to an adatom (interacting) on a host surface (metallic or semiconductor), and (ii) a quantum dot connected to source and drain leads and side-coupled to a superconducting nanowire sustaining Majorana zero modes (Kitaev chain). Both problems are studied within the Green’s functions approach, which allows us to determine the transport properties of the system. In the first setup, due to the ferromagnetic and nonmagnetic ‘natures’ of the tip and

APA, Harvard, Vancouver, ISO, and other styles

48

Santos, Marcelo Meireles dos. "A evolução temporal de sistemas de spins 1/2 congelados no espaço e descritos pelo modelo de Heisenberg." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-27032013-120632/.

Full text

Abstract:

Este projeto se destina ao estudo de sistemas quânticos não relativísticos de dois, quatro e oito níveis de energia que descrevem partículas com spin s=1/2 sujeitas à ação de campos externos e interagentes entre si. São apresentadas soluções exatas para as equações que regem esses sistemas. Tais sistemas possuem uma vasta aplicação em diversas áreas da física, dentre as quais é possível destacar a computação quântica. Possíveis aplicações dos resultados são a construção de portas lógicas quânticas universais. Estas portas lógicas quânticas representam um elemento essencial no desenvolvimento d

APA, Harvard, Vancouver, ISO, and other styles

49

Deng, Kuangyin. "Exchange and superexchange interactions in quantum dot systems." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/102342.

Full text

Abstract:

Semiconductor quantum dot systems offer a promising platform for quantum computation. And these quantum computation candidates are normally based on spin or charge properties of electrons. In these systems, we focus on quantum computation based on electron spins since these systems has good scalability, long coherence times, and rapid gate operations. And this thesis focuses on building a theoretical description of quantum dot systems and the link between theory and experiments. In many quantum dot systems, exchange interactions are the primary mechanism used to control spins and generate e

APA, Harvard, Vancouver, ISO, and other styles

50

Grijalva, Sebastian. "Boundary effects in quantum spin chains and Finite Size Effects in the Toroidal Correlated Percolation model." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP093.

Full text

Abstract:

Cette thèse est divisée en deux parties : la première présente un modèle statistique en deux dimensions de percolation corrélée sur un réseau toroïdal. Nous présentons un protocole pour construire des surfaces corrélées à longue portée sur la base de surfaces gaussiennes fractionnaires, puis nous relions les ensembles de niveaux à une famille de modèles de percolation corrélés. Les clusters émergents sont ensuite étudiés numériquement, et nous testons leur symétrie conforme en vérifiant que les corrections de taille finie de connectivité à deux points suivent les prédictions de la théorie des

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!