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Hittade 4 uppsatser som matchar ovanstående sökkriterier.

  1. 1. The effect of disorder on the axial anomaly in a lattice model in 1 + 1 dimensions

    Master-uppsats, KTH/Fysik

    Författare :Agnes Wattrang; [2023]
    Nyckelord :Axial anomaly; tight-binding model; semiclassical physics; correlated disorder.; Axial kiral anomali; tätbindningsmodell; semiklassisk fysik; korrelerad oordning;

    Sammanfattning : This work investigates the effect of a disorder potential, that represents impurities/dislocations in the lattice, on the time-dependent signature of the axial anomaly in a one-band tight-binding model in one spatial dimension. The tight-binding model is solved numerically and the simulation results are compared with a semiclassical expression for the time-dependent axial density, n5(t), due to Nielsen and Ninomiya [1]. LÄS MER

  3. 2. Effects of power-law correlated disorder on a 3D XY model

    Master-uppsats, KTH/Fysik

    Författare :Philip Broms; [2022]
    Nyckelord :Condensed matter physics; Ising model; XY model; Markov Chain Monte Carlo; Phase transition; Disorder; Theoretical physics; Wolff algorithm; Kondenserade materians teori; Isingmodell; XY-modell; Markovkedje-Monte Carlo-metoder; Teoretisk fysik; Oordning; Fasövergångar; Wolffalgoritmen;

    Sammanfattning : This thesis investigates the effects of power-law correlated disorder on a three-dimensional XY model and the Weinrib-Halperin disorder relevance criterion’s pre-dictive ability. Ising models are used as a map to realise disorder couplings. LÄS MER

  4. 3. Models of superconductors with correlated defects

    Master-uppsats, KTH/Fysik

    Författare :Jakob Bolin; [2022]
    Nyckelord :Quantum phase transition; correlated disorder; 3D XY model; Monte Carlo simulation; worm algorithm; winding number; superfluid density; Kvantfasövergång; korrelerad oordning; 3D XY modell; Monte Carlo simulering; worm algoritmen; vindlingstal; supraledande täthet;

    Sammanfattning : The quantum phase transition between groundstates of a system with correlated disorder near absolute zero is studied. The computations are based on Monte Carlo methods and the worm algorithm which is an effective method to simulate basic models like the Ising and XY model by making use of global Monte Carlo moves given by modified random walks. LÄS MER

  5. 4. Spreading of wave packets in lattices with correlated disorder

    Magister-uppsats, Institutionen för fysik, kemi och biologi

    Författare :Jakob Rönnbäck; [2011]
    Nyckelord :Markov chain; Correlation Function; Memory Function; Tight-Binding; Lyapunov Exponent;

    Sammanfattning : It is known that a highly ordered medium allows certain wave functions to move unhindered throughout and in this manner achieve delocalization. It is also known that if one introduces disorder into a medium, wave packets will not be able to move as freely and will instead be trapped or localized. LÄS MER