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.