Pusan National University Researchers Have Developed a Hybrid Quantum Network with Indistinguishable Quantum Sources

Researchers from Pusan National University and the Ulsan National Institute of Science and Technology have reached a significant milestone in quantum communication. The team successfully demonstrated photon interference between two distinct quantum light sources: a warm cesium atomic ensemble and a semiconductor quantum dot. This experiment proves that independent, physically different systems can work together in a single architecture.

Scaling quantum networks requires a combination of reliable storage and high-rate photon generation. Atomic systems are useful for storage and synchronization, while quantum dots excel at producing bright, high-frequency light. Previously, connecting these two disparate sources required complex modifications that often resulted in data loss. By overcoming the barrier between these systems, this research offers a new way to build functional, large-scale networks.

The team achieved a Hong–Ou–Mandel interference visibility of 0.65 without the need for external spectral or temporal filtering. By cooling the quantum dots to 12.5 K, they matched the wavelengths of the cesium-generated photons to reach a high degree of indistinguishability. This direct interference between physically dissimilar sources simplifies the design of future quantum infrastructure.

This development provides a foundation for more stable distributed quantum networks and advanced computing setups. Professor Han Seb Moon notes that this hybrid approach effectively bridges the gap between generation and storage. As researchers look toward building a global quantum internet, these findings offer a practical path for connecting remote quantum emitters using a shared frequency standard.