  Hexagonal boron nitride (hBN) has emerged as a promising ultrathin host of
single photon emitters (SPEs) with favorable quantum properties at room
temperature, making it a highly desirable element for integrated quantum
photonic networks. One major challenge of using these SPEs in such applications
is their low quantum efficiency. Recent studies have reported an improvement in
quantum efficiency by up to two orders of magnitude when integrating an
ensemble of emitters such as boron vacancy defects in multilayered hBN flakes
embedded within metallic nanocavities. However, these experiments have not been
extended to SPEs and are mainly focused on multiphoton effects. Here, we study
the quantum single photon properties of hybrid nanophotonic structures composed
of SPEs created in ultrathin hBN flakes coupled with plasmonic silver
nanocubes. We demonstrate > 200% plasmonic enhancement of the SPE properties,
manifested by a strong increase in the SPE fluorescence. Such enhancement is
explained by rigorous numerical simulations where the hBN flake is in direct
contact with the Ag nanocubes that cause the plasmonic effects. The presented
strong and fast single photon emission obtained at room-temperature with a
compact hybrid nanophotonic platform can be very useful to various emerging
applications in quantum optical communications and computing.
