  Fluorescent atomic defects, especially in dielectric materials, such as
diamond are quite promising for several emerging quantum applications. However,
efficient light extraction, directional emission, and narrow spectral emission
are key challenges. We have designed dielectric metasurface exploiting
Mie-resonance and the Kerker condition to address these issues. Our designed
diamond metasurface, tailored for nitrogen-vacancy (NV) defect centers in
diamond, predicts up to 500x improvement in the collection of 637 nm (zero
phonon line) photons over that from the bare diamond. Our design achieves
highly directional emission, predominantly emitting in a 20 degree lobe in the
forward direction. This makes light collection more efficient, including for
fiber-based collection. The predicted results are stable against the position
of the emitter placed in the metaelement, thus alleviating the challenging
fabrication requirement of precise positioning of the defect center. Equally
importantly, our design approach can be applied to enhance single photon
emission also from other defects such as SiV, other materials such as hBN, and
other sources such as quantum dots.
