Long-Range Dipole-Dipole Interactions Enabled with Guided Plasmons of Matched Nanoparticle-on-Mirror Antenna Pairs

Abstract: Ruling a wide range of phenomena, dipole-dipole interactions (DDI) are typically constrained to the short range due to their rapid decay with the increasing dipole separations, limiting the performance in long-range applications. By judiciously designing the photonic structures that control the two-point Green's functions of the electromagnetic environment, the spontaneous emission of quantum emitters (luminescence) and their interactions (e.g., F\"orster energy transfer) can be conveniently tuned. In this paper, we designed a matched nanoparticle-on-mirror antenna pair with enhanced DDI guided by surface plasmon polaritons confined to the metal substrate, which ensures concentrated and enhanced interaction over long ranges of tens of wavelengths. The long-range ($\sim 10 \lambda$) DDI between donor-acceptor emitters is enhanced by $6\times 10<sup>{3}$ times respective to bare gold film, and $4.4\times 10<sup>{4}$ times respective to vacuum. Our result provides a promising testbed for investigating long-range DDI phenomena on the nanoscale.