Strong-field-driven dynamics and high-harmonic generation in interacting 1D systems*

We explore the role of band structure and Coulomb interactions in solid-state high-order harmonic generation (HHG) by studying the optical response of linear atomic chains and carbon nanotubes to intense ultrashort pulses [1]. We solve the single-particle density matrix equation of motion in the presence of intense optical fields, incorporating tight-binding electronic states and a self-consistent electron-electron interaction. The doping can be tuned to describe metals, regular insulators, and topological insulators. Our study reveals the important role played by electron interactions in HHG, due in part to the presence of collective optical resonances. We find that doped semiconductors generate high harmonics more efficiently than their metallic and undoped counterparts. We also show results for HHG in more realistic quasi-1D structures such as carbon nanotubes, with behavior similar to that of atomic chains. Our findings apply to a broad variety of solid-state and molecular systems and can be extended to optimize HHG platforms or identify new solid-state alternatives in the context of nonlinear plasmonics.
[1] S. de Vega et al. Phys. Rev. Research 2, 013313 (2020).