High harmonic generation spectroscopy of laser induced phase transitions in strongly correlated systems

The advent of attosecond spectroscopy, in particular high harmonic generation spectroscopy, has led to advances in following electronic dynamics in atoms and molecules on their natural timescale. The recent discovery of the high harmonic generation in bulk solids has opened the door for applying HHG spectroscopy for ultrafast investigations of the electronic dynamics in the condensed phase, including the demonstration of the dynamical Bloch oscillations, the analysis of the relative importance of the intraband and interband current in harmonic generation, the reconstruction of the band structure in ZnO. In particular, recent work elegantly demonstrated the power of HHG spectroscopy for reconstructing NIR, MIR and THz driven nonlinear response in time, with temporal resolution at the small fraction of the laser cycle. In the case of intense THz drivers, the information about the temporal profile of the nonlinear dipole was reconstructed with an uncertainty of about 1.5 fs.