  Color centered-based single photon emitters in hexagonal boron nitride (h-BN)
have shown promising photophysical properties as sources for quantum light
emission. Despite significant advances towards such a goal, achieving
lifetime-limited quantum light emission in h-BN has proven to be challenging,
primarily due to various broadening mechanisms including spectral diffusion.
Here, we propose and experimentally demonstrate suppression of spectral
diffusion by applying an electrostatic field. We observe both Stark shift
tuning of the resonant emission wavelength, and emission linewidth reduction
nearly to the homogeneously broadened lifetime limit. Lastly, we find a cubic
dependence of the linewidth with respect to temperature at the homogeneous
broadening regime. Our results suggest that field tuning in electrostatically
gated heterostructures is promising as an approach to control the emission
characteristics of h-BN color centers, removing spectral diffusion and
providing the energy tunability necessary for integrate of quantum light
emission in nanophotonic architectures.
