Sökning: "matter theory"

Visar resultat 6 - 10 av 739 avhandlingar innehållade orden matter theory.

  1. 6. Transport theory and finite element methods for mesoscopic superconducting devices

    Författare :Kevin Marc Seja; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; non-equilibrium superconductivity; finite element methods; unconventional superconductors; quasiclassical theory; transport theory;

    Sammanfattning : At low temperatures, electrons in a superconductor exhibit pairing correlations that result in a macroscopic, phase-coherent ground state. This leads to peculiar electromagnetic properties such as the flow of dissipationless charge currents and expelling of external magnetic fields. LÄS MER

  2. 7. Spin ice and demagnetising theory

    Författare :Mikael Twengström; Patrik Henelius; Peter Holdsworth; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Geometrical frustration; spin ice; Monte Carlo simulations; demagnetising theory; special temperatures; Ewald summation; neutron scattering; structure factors; loop algorithms; parallel tempering; frustrated ferromagnets; equilibration issues; long-range interactions; exchange interactions.; Fysik; Physics;

    Sammanfattning : Frustration, or the inability to simultaneously minimise all local interactions is, a phenomenon occurring in a broad number of physical systems. We will in this thesis focus on a class of frustrated ferromagnetic materials called spin ices and how both numerical and experimental techniques can be used to understand their properties. LÄS MER

  3. 8. Cosmoparticle Physics and String Theory

    Författare :Stefan Sjörs; Marcus Berg; Joseph Conlon; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Supersymmetry; dark matter; cosmology; inflation; modifications of gravity; string theory; flux compactifications; perturbative string theory; teoretisk fysik; Theoretical Physics;

    Sammanfattning : This thesis deals with phenomenological and theoretical aspects of cosmoparticle physics and string theory. There are many open questions in these topics. In connection with cosmology we would like to understand the detailed properties of dark matter, dark energy, generation of primordial perturbations, etc. LÄS MER

  4. 9. Ultracold rubidium atoms in periodic potentials

    Författare :Robert Saers; Anders Kastberg; Svante Jonsell; Jan W. Thomsen; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Bose-Einstein condensation; optical lattice; quantum phase transition; experiment; theory; Condensed matter physics; Kondenserade materiens fysik;

    Sammanfattning : This thesis includes both experimental and theoretical investigations, presented in a series of eight papers. The experimental part ranges from the construction procedures of an apparatus for Bose-Einstein condensates, to full scale experiments using three different set-ups for ultracold atoms in optical lattices. LÄS MER

  5. 10. One-dimensional theory of the quantum Hall system

    Författare :Emil Johansson Bergholtz; Anders Karlhede; Nicholas Read; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; fractional quantum Hall effect; thin torus; spin chains; conformal field theory; strong correlations; non-abelian states; Condensed matter physics; Kondenserade materiens fysik; Theoretical Physics; teoretisk fysik;

    Sammanfattning : The quantum Hall (QH) system---cold electrons in two dimensions in a perpendicular magnetic field---is a striking example of a system where unexpected phenomena emerge at low energies. The low-energy physics of this system is effectively one-dimensional due to the magnetic field. LÄS MER