Sustainability cost of defect engineering in color centers for quantum communications

Quantum communication relies on optically active color centers for scalable spin-photon networking, yet the sustainability implications of defect engineering remain largely unexplored. We comparatively evaluate twenty host crystal-defect generation combinations across diamond, SiC, h-BN, GaN, ZnO using ion implantation, e-beam irradiation, laser writing, and heteroepitaxial growth techniques. A multi-attribute cradle-to-gate framework integrating life cycle, chemical hazard, human health toxicity, and technoeconomic assessments reveals distinct thermodynamic, chemical, health, and economic tradeoffs emerge across defect engineering pathways. h-BN paired with laser writing shows the lowest overall burdens, with low energy demand, global warming potential <20 kg CO₂ eq./chip, minimal hazard/toxicity profiles, and lowest fabrication cost. SiC provides a balanced near-term pathway by retaining strong quantum functionality while moderating sustainability burdens. ZnO and GaN show selective process-level advantages for integrated photonics, whereas diamond remains burden-intensive due to energy-demanding growth and complex post-defect stabilization requirements. Identified greener interventions enable scalable and resource-conscious quantum communication hardware.