Adaptive Cavity Control of Single-Photon Emission from Hexagonal Boron Nitride

Atom-like defects in hexagonal boron nitride (hBN) are promising room-temperature quantum light sources, but their stochastic spatial positions and emitter-dependent transition energies have limited deterministic cavity coupling and active control of their emission dynamics. Here, we demonstrate the adaptive cavity control of quantum emission from individual hBN single-photon emitters at room temperature. Using tip-enhanced cavity spectroscopy, we spatially position a nanoscale optical cavity over selected emitters and spectrally match the cavity response to the excitation laser and emitter zero-phonon line. This adaptive spatio-spectral control enables selective enhancement of excitation and spontaneous emission pathways rather than simple photoluminescence amplification. By switching between excitation-dominated and emission-dominated coupling regimes, we reshape photon statistics, enhancing antibunching or inducing controlled bunching, depending on the cavity condition. These results establish adaptive cavity control as a strategy for engineering the brightness, lifetime, saturation behavior, and photon statistics in hBN quantum emitters.