One-Dimensional Plasmons and Hybridized Coupled Polaritons in Carbon Nanotubes

This paper presents real-time time-dependent density functional theory (TDDFT) ab initio simulations of selected armchair carbon nanotubes (CNTs). By scaling the lengths of CNTs, we provide a comprehensive analysis of the Tomonaga–Luttinger (T–L) 1-D plasmon velocities, confirming consistency with theoretical predictions and experimental observations. Our findings include detailed visual representations of excitation densities at various resonances. Furthermore, we explore the coupling between T–L plasmons and single electron excitations, identifying distinct 1-D polariton behaviors, such as strong harmonic generation due to nonlinearities, as well as energy gaps that differ from conventional 2-D polaritons. The study highlights the unique properties of armchair single-walled carbon nanotubes as low-loss nanocavity resonators, demonstrating potential applications in strong light-matter coupling and other nanophotonic devices. The simulation framework employed here opens avenues for further research into 1-D plasmonic phenomena and electronic spectroscopy in complex nanostructures.