Enhancing Quantum Emission from Spin Defects in Hexagonal Boron Nitride with a Plasmonic Nanocavity

We report a 250-fold photoluminescence enhancement of ${{\text{V}}_{{{\text{B}}^ - }}}$ spin-defects in hBN by coupling them to nanopatch antennas (NPA). Considering the relative size of the NPAs and laser-spot, an actual enhancement of 1695 times is determined.