Dynamic Interplay of Nonlocal Recombination Pathways in Quantum Emitters in Hexagonal Boron Nitride

Optically active defects in wide bandgap materials play a central role in several emerging applications in quantum information and sensing as they allow for manipulating and harvesting the internal degrees of freedom of single electrons with optical means. Interactions among defect states and with the surrounding environment represent a crucial feature for sensing but can severely hamper the coherence of the quantum states and prevent an efficient integration with photonic architectures due to unpredictable spectral instability. Understanding and controlling defect interactions would mitigate the effects of spectral instabilities and enable quantum applications based on long-range interactions. Here, we investigate the photoluminescence spectral dynamics of quantum emitters in defective hexagonal boron nitride (hBN), a material whose emission spectrum notoriously displays spectral wandering and diffusion, and we identify several optical transitions with discrete energy jumps. We associate the spectral jumps with the interplay amid competing recombination pathways available to the defect states in a process like donor-acceptor-pairs (DAP). The discrete spectral jumps observed in the emission spectrum of hBN arise from interactions between the harmonic states of nitrogen π orbitals of delocalized defects, and their energies can be ascribed to a DAP-like transition sequence. Our results allow mapping of the defect geometry in an hBN lattice, setting the basis for mitigating the effects of spectral jumping in this platform and paving the way toward using the long-range interaction of defect ensembles for quantum technology.