Sökning: "Hubbard Model"

Visar resultat 11 - 15 av 36 avhandlingar innehållade orden Hubbard Model.

  1. 11. Many-photon effects in time-resolved second harmonic generation from systems in optical cavities

    Författare :Megha Gopalakrishna; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Second harmonic generation; Cavity optics; Non-linear optics; Cavity leakage; Ultracold atoms; Dicke model; Exact diagonalization; Non-equilibrium Green s functions; Fysicumarkivet A:2024:Gopalakrishna;

    Sammanfattning : Second harmonic generation is popular due to its numerous applications in different technologies dealing with multiple fields of science. The rapid technical advancement with the second harmonic generation demands parallel development in the theoretical understanding. LÄS MER

  3. 12. Numerical Renormalization, Doped Antiferromagnets, and Statistics - Topics in Low Dimensional Physics

    Författare :Martin Andersson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Josephson junctions; matrix-product states; fictitious flux; phase-separation; renormalization; stripes; t-J model; anyons; DMRG;

    Sammanfattning : The first part of the thesis deals with so called numerical renormalization group methods, and in particular the density-matrix renormalization group (DMRG). This method performs extremely well for large one-dimensional quantum systems like spin-chains and Hubbard models. LÄS MER

  4. 13. Theoretical methods for the electronic structure and magnetism of strongly correlated materials

    Författare :Inka L. M. Locht; Igor Di Marco; Silke Biermann; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; dynamical mean field theory DMFT ; Hubbard I approximation; strongly correlated systems; rare earths; lanthanides; photoemission spectra; ultrafast magnetization dynamics; analytic continuation; Padé approximant method; two-particle Green s functions; linear muffin tin orbitals LMTO ; density functional theory DFT ; cerium; stacking fault energy.; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : In this work we study the interesting physics of the rare earths, and the microscopic state after ultrafast magnetization dynamics in iron. Moreover, this work covers the development, examination and application of several methods used in solid state physics. The first and the last part are related to strongly correlated electrons. LÄS MER

  5. 14. Comparisons between classical and quantum mechanical nonlinear lattice models

    Författare :Peter Jason; Magnus Johansson; Jonas Larson; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Discrete Breathers; Bose-Einstein-Condensation; Instabilities; Oscillatory Instabilities; Classical-Quantum correspondence; Bose-Hubbard model; DNLS; discrete nonlinear Schrödinger equation; nonlinear; nonlinear lattice models; compacton;

    Sammanfattning : In the mid-1920s, the great Albert Einstein proposed that at extremely low temperatures, a gas of bosonic particles will enter a new phase where a large fraction of them occupy the same quantum state. This state would bring many of the peculiar features of quantum mechanics, previously reserved for small samples consisting only of a few atoms or molecules, up to a macroscopic scale. LÄS MER

  7. 15. Strong Correlation Effects in Bosonic and Fermionic Systems Through an Unbiased Quantum Monte Carlo Approach

    Författare :Emil Blomquist; Egor Babaev; Johan Carlström; Barbara Capogrosso Sansone; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fysik; Physics; Teoretisk fysik; Theoretical Physics;

    Sammanfattning : Strongly interacting many-body quantum systems constitute some of the most challenging problems in physics, and exact analytical solutions are rare. In this thesis, we will investigate the models of two such systems numerically using the unbiased worm-algorithm Monte Carlo method. LÄS MER