Scalable integration of quantum emitters into photonic integrated circuits

Scaling up photonic quantum devices to reach complexities allowing to solve real-world problems requires a platform enabling scalable integration of solid-state quantum emitter with a high yield. Their nanometer-size together with their excellent quantum optical properties make them the ideal candidates for on-chip photonic quantum technologies. However, robust, scalable integration remains elusive. Here, we discuss the state-of-the-art methods to integrate quantum emitters into photonic integrated circuits, emphasizing the pros and cons of the integration methods applicable for specific quantum emitters. Based on our thorough comparison we give our perspective on the most promising approaches and how to overcome the remaining challenges.