Superballistic Transport of Thermal Photons in Confined Many-Body Systems.

Ballistic transport is traditionally regarded as a limiting regime for scattering-free energy transfer. Here, we predict a superballistic radiative heat transport regime that surpasses this limit in dilute chains of plasmonic nanoparticles confined within cavities. This anomalous regime exhibits superlinear scaling of the effective thermal conductivity (κ∼L^{1.5}) and originates from the amplification of long-range interactions mediated by cavity-guided modes. Our results establish a framework for ultrafast photonic heat transport and open pathways for thermal management, information processing, and energy transfer in quantum and nanoscale systems.