Surface plasmon dynamics in nanoscale materials: Fundamental physics, state-of-the-art, and future prospects

Surface plasmon dynamics in nanoscale materials have emerged as a cornerstone of modern nanophotonics, enabling unprecedented manipulation of light at subwavelength scales. This review provides a comprehensive overview of the fundamental physics governing plasmonic excitations, including localized surface plasmons and propagating surface plasmon polaritons, and their interaction with matter at the quantum and classical levels. We critically examine the state-of-the-art developments in plasmonic sensing, nanomedicine, photocatalysis, energy harvesting, optical communication, and quantum plasmonics, highlighting their transformative potential across interdisciplinary domains. Special emphasis is given to recent advances such as ultrafast plasmon dynamics, strong coupling regimes, plasmon-exciton hybrid systems, and topological plasmonics, which pave the way for next-generation plasmonic devices. Challenges such as high intrinsic losses, fabrication limitations, and integration with complementary technologies are systematically discussed, alongside emerging strategies to address them through low-loss materials, machine learning-driven design, and sustainable plasmonic approaches. The review concludes with a forward-looking perspective on the evolving role of plasmonics in nanoscience, forecasting its critical contributions to future optoelectronics, quantum information processing, and green technologies.