Quantum key distribution proven over 400G DWDM network in Japan
PacketLight Networks and NEC have demonstrated quantum key distribution (QKD) over a 400 gigabit per second dense wavelength division multiplexing (DWDM) network, showing a practical method for enhancing quantum-safe communications.
The collaboration took place at NEC's laboratories in Japan, where NEC's QKD system was integrated with PacketLight's PL-4000M 600G Muxponder. During the demonstration, the quantum signal was transmitted over a dedicated fibre that operated in parallel with the main data link fibre. This configuration was designed to safeguard the quantum signal's integrity without impacting the performance of the existing 400G data traffic over the DWDM network.
The dual-fibre approach addresses industry concerns about maintaining high data throughput while introducing QKD for enhanced security. By running the QKD channel alongside the main link, the method enables network operators to implement quantum encryption without extensive changes to their current infrastructure.
System setup and results
During the demonstration, encrypted data was transmitted at full 100% throughput and maintained consistently low latency, according to results validated with a 100GbE tester. The separate fibre carrying the QKD channel operated without interfering with the main data link, affirming that quantum key distribution can coexist with high-performance DWDM traffic.
This demonstration is considered by the companies as support for a scalable and cost-efficient framework that could be widely adopted in network environments requiring enhanced security. The method is intended to enable secure key exchange for real-world applications while allowing existing systems to maintain operational ease and cost control.
Industry perspectives
Koby Reshef, Chief Executive Officer of PacketLight, emphasised the collaborative nature of the project and the new avenues it may present for secure data transmission.
"The integration of NEC's QKD technology with PacketLight's DWDM/OTN devices paves the way for enhanced secure data transmission," said Koby Reshef, CEO of PacketLight. "We take pride in our involvement in this cooperation and eagerly anticipate the market's response to the new opportunities it presents."
Yoichiro Ito, Director of Innovation Product Solutions Group, Defence Network Department, NEC, outlined NEC's longstanding commitment to QKD and highlighted the significance of successfully combining the companies' technologies.
"We are delighted to announce the successful completion of our joint demonstration with PacketLight," said Yoichiro Ito, the Director of Innovation Product Solutions Group, Defence Network Department, NEC. "NEC has a research base of QKD system in Japan and has led the advancement of it for over 20 years. Through this demonstration, we verified the interoperability of our QKD system with PacketLight's equipment, which confirmed its applicability in more diverse usage scenarios. We will continue to strengthen our collaboration with partners and work toward creating even greater value."
Technical verification
Throughout the demonstration, teams from PacketLight and NEC tested system compatibility, encryption performance, and latency levels. The interoperability of the QKD system with PacketLight's transport equipment was validated, which the companies stated as confirmation that their combined technologies can be applied across different operational contexts.
The companies' approach shows that quantum technologies can be introduced as an overlay on existing network infrastructure, operating independently yet in parallel with conventional high-speed data links.
The demonstration was set up so that the QKD channel had its own dedicated transmission path, while commercial DWDM data continued on the main fibre. The result, according to both PacketLight and NEC, is a practical path for network operators to implement quantum-safe key distribution without requiring extensive replacement or redesign of existing systems.