Nanoscale axial position and orientation measurement of hexagonal boron nitride quantum emitters using a tunable nanophotonic environment.

Color centers in hexagonal boron nitride ( h BN) have emerged as promising candidates for single-photon emitters (SPEs) due to their bright emission characteristics at room temperature. In contrast to mono- and few-layered h BN, color centers in multi-layered flakes show superior emission characteristics such as higher saturation counts and spectral stability. Here, we report a method for determining both the axial position and three-dimensional dipole orientation of SPEs in thick h BN flakes by tuning the photonic local density of states using vanadium dioxide (VO ₂ ), a phase change material. Quantum emitters under study exhibit a strong surface-normal dipole orientation, providing some insight on the atomic structure of h BN SPEs, deeply embedded in thick crystals. Next, we optimized a hot pickup technique to reproducibly transfer the h BN flake from VO ₂ /sapphire substrate onto SiO ₂ /Si substrate and relocated the same emitters. Our approach serves as a practical method to systematically characterize SPEs in h BN prior to integration in quantum photonics systems.
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