Author: Eduardo Bernal Molinero - ICMM-CSIC (read an interview here)
Supervised by: Rui E. Silva (ICMM-CSIC)
When: April, 10 - 2PM
Where: Salón de Actos, ICMM
Abstract: Light-matter interactions drive many physical phenomena, and in the strong-field regime (where intense light reshapes system dynamics) they become particularly striking. High-harmonic generation (HHG), a hallmark of this regime, is well studied in atoms and molecules but remains less explored in solids. This thesis investigates strong-field effects in condensed matter, addressing this gap.
Studying HHG in periodic solids poses challenges, which we tackle using the Semiconductor Bloch Equations combined with Wannier functions. Applying this framework, we examine HHG in bulk semiconductors, demonstrating its potential as a spectroscopic tool to probe material properties. Notably, we use HHG to determine the magic angle in twisted bilayer graphene and to time-resolve phase transitions.
Electron-electron interactions, central to condensed matter physics, have been largely neglected in strong-field studies. We incorporate these interactions into our model and apply it to two-dimensional materials, where excitons (bound electron-hole pairs) play a crucial role in HHG. We establish a connection between exciton physics and Rydberg states and explore how intense laser fields induce an insulator-to-metal transition in the Hubbard model, designing a laser setup to control and monitor this transition via HHG.
To further enhance our understanding, we introduce the Semiconductor Wannier Equations, a novel real-space approach to computing optical responses in solids, overcoming the limitations of momentum-space methods. This framework provides deeper physical insight, particularly by linking real-space dephasing to atomic HHG trajectories. Applying this method to valleytronics, we demonstrate ultrafast logical operations on the valley degree of freedom using laser pulses.
