14 mars 2022

Seminar by Matheus Lazarotto – University of São Paulo, Brasil

Chaotic dynamics in a 2D periodic potential
AbstractSpatial diffusion of particles in periodic potential models has provided a good framework for studying the role of chaos in global properties of classical systems. A bidimensional “soft” billiard, which is a classical dynamics derived from an optical lattice hamiltonian system, is used to study diffusion transitions under variation of the control parameters. Sudden transitions between normal and ballistic regimes are found and characterized by inspection of topological changes in phase-space. Transitions correlated with increases in global stability area are shown to occur for energy levels where local maxima points become accessible, deviating trajectories approaching them. These instabilities promote a slowing down of the dynamics and an island myriad bifurcation phenomenon (fig 1-B), along with the suppression of long flights within the lattice. Other diffusion regime variations occurring within small intervals of control parameters are shown to be related to the emergence of a set of orbits with long flights, thus altering the total average displacement for long integration times but without global changes in phase-space.
Short bioMatheus Lazarotto is a PhD student at University of São Paulo (Brazil). He is currently visiting PIIM laboratory (Turbulence Plasma team) for 6 months in the framework of the CAPES/COFECUB program. With a bachelor background in physics and a master’s in molecular dynamics, he currently works with dynamical hamiltonian systems and chaos, particularly with low-dimensional chaotic models in lattice potentials and wave-particle interaction.
Health conditions permitting, the talk will be preceded by a welcome breakfast at 10:15.
14 mars 2022, 10h4512h15
PIIM laboratory