Search for dissertations about: "quantum phase transitions"

Showing result 11 - 15 of 58 swedish dissertations containing the words quantum phase transitions.

  2. 11. Superfluid Phase Transitions in Disordered Systems

    Author : Hannes Meier; Mats Wallin Wallin; Peter Olsson; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES;

    Abstract : This thesis presents results from large scale Monte Carlo simulations of systems subject to a superfluid phase transition in the presence of disorder. The simulations are performed by state-of-the-art, collective Monte Carlo algorithms treating phase degrees of freedom in effective models with amplitude fluctuations integrated out. READ MORE

  4. 12. Entanglement and Quantum Computation from a Geometric and Topological Perspective

    Author : Markus Johansson; Marie Ericsson; Jens Eisert; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Quantum Information; Geometric Phases; Topological Phases; Entanglement; Quantum Computation;

    Abstract : In this thesis we investigate geometric and topological structures in the context of entanglement and quantum computation.A parallel transport condition is introduced in the context of Franson interferometry based on the maximization of two-particle coincidence intensity. READ MORE

  5. 13. Designing and Tuning the Properties of Materials by Quantum Mechanical Calculations

    Author : Jailton Souza de Almeida; Rajeev Ahuja; Patrizia Monachesi; Uppsala universitet; []
    Keywords : Physics; Density Functional Theory; Electronic Structure; Phase Transitions; High Pressure; Optical Properties; Dielectric Functions; Semiconductors; Metals; Fysik;

    Abstract : In many materials, changes in chemical composition, pressure or temperature can induce metal to insulator transitions. It is recently observed in yttrium hydride, for example, changes from a shiny mirror (YH2) to a transparent window (YH3), which has important technological application in optical devices. READ MORE

  6. 14. Topological Phase Transitions in Magnetic Nanostructures of Dirac Materials

    Author : Nezhat Pournaghavi; Carlo M. Canali; Michael Flatté; Linnéuniversitetet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Topological insulators; Magnetic materials; Quantum anomalous Hall effect; Topological magneto electric effect; Dirac semimetals; Weyl semimetals; Condensed Matter Physics; Kondenserade materians fysik;

    Abstract : Over the past two decades, the discovery of topological Dirac materials, such as topological insulators and semimetals, has defined a new paradigm in condensed matter physics and established new platforms for realizing spin electronic devices and quantum computing. The novel quantum properties of these materials, which are mainly due to the presence of strong spin-orbit coupling, are invariant under topological transformations, making them more resilient to structural disorder, electromagnetic and thermal fluctuations in comparison to the conventional silicon-based materials. READ MORE

  7. 15. Type-II interband quantum dot photodetectors

    Author : Oscar Gustafsson; Mattias Hammar; Wenquan Ma; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; photodetector; quantum dot; infrared; MOVPE; thermal imaging; type-II; photoluminescence; III V; InSb; InGaSb; InAs; SRA - ICT; SRA - Informations- och kommunikationsteknik;

    Abstract : Photon detectors based on single-crystalline materials are of great interest for high performance imaging applications due to their low noise and fast response. The major detector materials for sensing in the long-wavelength infrared (LWIR) band (8-14 µm) are currently HgCdTe (MCT) and AlGaAs/GaAs quantum wells (QW) used in intraband-based quantum-well infrared photodetectors (QWIPs). READ MORE