Toshiba Tests Show QKDs Can Be Integrated Into Existing Regional Optical Communication Networks

Toshiba Europe is one of the pioneers of quantum key distribution (QKD) technology. Its latest tests have shown that deploying the technology on a high-speed network nearly 200 kilometers long is effective.
In its experiments with network operator Orange, Toshiba Europe evaluated the performance of a QKD system using 1310 nm wavelength transmission, co-propagated with a dense wavelength division multiplexing (DWDM) data channel using nearly 1550 nm transmission.
According to their research paper published earlier this month in the Journal of Lightwave Technology, it is feasible to transmit QKD-protected 100 Gigabit Ethernet data streams alongside 400 Gb/s data channels.
Andrew Shields of Toshiba Europe and colleagues said, "Encryption was demonstrated while co-propagating." They used three QKD systems and two trusted nodes to ensure the formation of a 184-kilometer link.
Last year, Toshiba and Orange had shown that QKD technology could be deployed on existing fiber networks alongside existing legacy data services, and the latest experiments sought to assess its suitability for more complex architectures that mimic current fiber network deployments.
"We've seen many organizations move from just assessing the threat posed by quantum computing to taking action to protect themselves," said Shields, head of Toshiba's Quantum Technologies division, "and these lab evaluations have shown that our QKD technology can be successfully deployed on real networks that are for real-world applications without further investment in new infrastructure."
Laurent Leboucher, CTO and SVP of Orange Innovation Networks, added, "Data security is a cornerstone of Orange's services, and we are delighted with the successful outcome of our partnership with Toshiba. Our (latest) work shows that QKD can be integrated into existing regional network infrastructure, marking a significant advancement in quantum secure communications."
In recent experiments, Toshiba and Orange tested two different types of QKD technology in an end-to-end system. Two 67-kilometer sections used Toshiba's long-haul technology, which features two optical fibers to carry quantum and classical signals, while a single 50-kilometer link used the company's multiplexed QKD technology, in which quantum channels are co-propagated with data channels.
The company, which has been at the forefront of QKD development for more than two decades, said the paper published with Orange provides experimental results and important considerations for any organization planning to implement QKD encryption.
The work demonstrates how high-speed quantum secure data encryption can be deployed over multi-link fiber networks and coexist with traditional data services using the type of network infrastructure commonly used in metro environments.
Toshiba Europe has also been working closely with companies such as BT, banking giants HSBC and SoftBank to demonstrate the high security and utility of its QKD system, and in September 2023 Toshiba formally opened its new £20 million Quantum Technology Center in Cambridge.