Sökning: "quantum phase transitions"

Visar resultat 1 - 5 av 58 avhandlingar innehållade orden quantum phase transitions.

  1. 1. Quantum Holonomy for Many-Body Systems and Quantum Computation

    Författare :Vahid Azimi Mousolou; Erik Sjöqvist; Rosario Fazio; Linnéuniversitetet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Quantum holonomy; geometric phase; quantum correlations; quantum phase transitions; quantum computation; Natural Science; Naturvetenskap; Physics; Fysik;

    Sammanfattning : The research of this Ph. D. thesis is in the field of Quantum Computation and Quantum Information. A key problem in this field is the fragile nature of quantum states. LÄS MER

  3. 2. Phase transitions in novel superfluids and systems with correlated disorder

    Författare :Hannes Meier; Mats Wallin; Asle Sudbø; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; condensed matter physics; phase transitions; critical phenomena; spin models; quantum phase transitions; quantum fluids; superfluidity; superconductivity; disordered systems; Bose glass; dirty bosons; vortex pinning; statistical mechanics; Monte Carlo simulation; Wolff algorithm; classical worm algorithm; Wang-Landau algorithm; Fysik; Physics;

    Sammanfattning : 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. LÄS MER

  4. 3. Phase Transitions in Large Oscillator Lattices

    Författare :Per Östborn; Antikens kultur och samhällsliv; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Matematisk och allmän teoretisk fysik; thermodynamics; statistical physics; phase transition; limit cycle oscillator; frequency entrainment; synchronization; sinus node; classical mechanics; Mathematical and general theoretical physics; arrhythmia; gravitation; quantum mechanics; relativity; klassisk mekanik; kvantmekanik; relativitet; statistisk fysik; termodynamik; Fysicumarkivet A:2003:Östborn;

    Sammanfattning : This thesis deals with large networks of limit cycle oscillators. A limit cycle oscillator is a dynamical system that has a periodic attractor in phase space, and is defined in continuous time. To each such oscillator one can associate a natural frequency. LÄS MER

  5. 4. Crystallization of the superconducting phase in unconventional superconductors

    Författare :Patric Holmvall; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; pattern formation; spontaneous symmetry breaking; Andreev bound states; mesoscopic superconductivity; phase crystals; thin superconducting films; phase transitions; non-local Ginzburg-Landau theory; time-reversal symmetry; flat bands; unconventional superconductivity; quasiclassical theory; translational symmetry; cuprates; inhomogeneous superconductivity;

    Sammanfattning : Superconductivity is a macroscopic quantum phenomenon, in the sense that a macroscopic number of electrons form a pair condensate, that occupies a single ground state. The electrons in this state are phase-coherent, breaking global U (1)-symmetry, and spatial variations of the phase imply superflows that usually cost kinetic energy, resulting in a uniform and rigid phase. LÄS MER

  7. 5. Quantum Coherence and Quantum-Vacuum Effects in Some Artificial Electromagnetic Media

    Författare :Jianqi Shen; Sailing He; Chris Phillips; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Quantum coherence; quantum vacuum; electromagnetically induced transparency; negative refractive index; artificial electromagnetic media; electric- and magnetic-dipole transitions; multilevel atomic vapors; transient evolution; Electrical engineering; electronics and photonics; Elektroteknik; elektronik och fotonik;

    Sammanfattning : The author of this thesis concentrates his attention on quantum optical properties of some artificial electromagnetic media, such as quantum coherent atomic vapors (various multilevel electromagnetically induced transparency vapors) and negative refractive index materials, and suggests some possible ways to manipulate wave propagations inside the artificial electromagnetic materials based on quantum coherence and quantum vacuum effects. In Chapters 1 and 2, the author reviews the previous papers on quantum coherence as well as the relevant work such as electromagnetically induced transparency (EIT), atomic population trapping and their various applications. LÄS MER