Tailoring Nitrogen‐Vacancy Centers in Diamond through HPHT Synthesis and Treatment

ABSTRACT With unique optical and spin properties, the negatively charged nitrogen‐vacancy (NV − ) center in diamond has become a leading physical platform for quantum information processing. Fabrication of NV centers involves three steps: introducing nitrogen atoms, creating lattice vacancies, and combining these two types of defects. The final step is typically achieved by high‐temperature annealing, as vacancy migration in diamond is thermally activated above 600°C. Compared to low‐pressure high‐temperature (LPHT) annealing, high‐pressure and high‐temperature (HPHT) treatment allows for much higher annealing temperatures and longer durations, providing new opportunities to optimize key metrics of NV centers. This short review summarizes recent experimental progress in this direction. Dense NV centers with good spin coherence and single NV centers with excellent optical properties have been produced through HPHT growth and post‐treatment of single‐crystal diamonds. In addition, structural imaging, optical characterization, and DFT calculations provide further insights into the dynamics of defect migration under high‐temperature annealing. These results offer new perspectives on the fabrication of color centers in diamond and other wide‐gap semiconductor materials, including silicon carbide and hexagonal boron nitride, for advanced quantum applications.