Sökning: "lattice physics"

Visar resultat 1 - 5 av 65 uppsatser innehållade orden lattice physics.

  1. 1. Towards a setup for narrowband terahertz generation through difference-frequency mixing of chirped ultrashort pulses

    Master-uppsats, Lunds universitet/Atomfysik; Lunds universitet/Fysiska institutionen

    Författare :Isa Clementsson; [2023]
    Nyckelord :Physics and Astronomy;

    Sammanfattning : Terahertz radiation is a useful tool for inducing lower-energy excitations in matter, where it can be used to cause structural changes through direct interaction with the crystal lattice. Sub-picosecond optical pulses can be used to generate intense broadband terahertz pulses through optical rectification in nonlinear crystals, reaching peak electric fields of several MV/m and conversion efficiencies as high as a few percent. LÄS MER

  3. 2. 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

  4. 3. Electron-skyrmion systems, in and out of equilibrium, and isolated or contacted to reservoirs

    Magister-uppsats, Lunds universitet/Matematisk fysik; Lunds universitet/Fysiska institutionen

    Författare :Emil Adam Jonatan Östberg; [2023]
    Nyckelord :skyrmion; skyrmions; NEGF; freen s function; quantum transport; non-equlibrium; topology; topological charge; skyrmionics; current induced; open system; Physics and Astronomy;

    Sammanfattning : A Kondo lattice skyrmion model in contact with a macroscopic environment is simulated to explore skyrmion dynamics, which is an extension of previous work. The system is simulated using non-equilibrium Green's functions within the generalized Kadanoff-Baym ansatz and the wide band limit. LÄS MER

  5. 4. Numerical Estimation of Critical Exponents in the 3D XY Model

    Master-uppsats, KTH/Fysik

    Författare :Christoffer Beiming; [2023]
    Nyckelord :Theoretical physics; Condensed matter theory; Phase transitions; XY model; Critical exponents; Computational physics; Monte Carlo simulations; Teoretisk fysik; Kondenserade materiens teori; Fasövergångar; XY-modellen; Kritiska exponenter; Beräkningsfysik; Monte Carlo simulering;

    Sammanfattning : The experimentally obtained value of the critical exponent ν is presently in significant disagreement with current theoretical predictions for the λ-universality class. We suggest two novel approaches of determining the exponents ν and η by utilizing the effects of finite size scaling. LÄS MER

  7. 5. Moving in the dark : Mathematics of complex pedestrian flows

    Magister-uppsats, Karlstads universitet/Fakulteten för hälsa, natur- och teknikvetenskap (from 2013)

    Författare :Meghashyam Veluvali; [2023]
    Nyckelord :Mathematical modelling of pedestrian dynamics; stochastic systems; evacuation time; random walk method; parabolic equation; finite difference method;

    Sammanfattning : The field of mathematical modelling for pedestrian dynamics has attracted significant scientific attention, with various models proposed from perspectives such as kinetic theory, statistical mechanics, game theory and partial differential equations. Often such investigations are seen as being a part of a new branch of study in the domain of applied physics, called sociophysics. LÄS MER