Toshiba Europe And Orange Demonstrates Continuity Of Implementing Quantum Key Distribution With Existing Equipment

Insider Summary

• Toshiba Europe and Orange presented research findings showing quantum key distribution can be successfully used on network providers’ existing fiber networks in addition to their current data services.
• The researchers say the work could help network operators reduce the cost of deploying QKD by eliminating the need to invest in dedicated quantum fiber infrastructure.
• Key Quote — “Validating the ability of our QKD technology to protect transmissions while using existing fiber networks is a major step forward in making quantum-secure communications accessible to today’s organizations. Working with a global operator like Orange to research and improve our technology is very important, and we look forward to continuing our work in this area.” — Andrew Shields, Head of Toshiba’s Quantum Technology Division.

PRESS RELEASE — Toshiba Europe Ltd. and global telecommunications operator Orange have demonstrated the feasibility of implementing Quantum Key Distribution (QKD) on existing commercial networks to protect transmissions from being decrypted by a quantum computer.

A new research paper presents findings from a joint test using Toshiba’s commercially available QKD technology, which demonstrates how the technology can be successfully used on a network provider’s existing fiber networks in addition to their current data services. This finding could help network operators reduce the cost of implementing QKD by eliminating the need to invest in dedicated quantum fiber infrastructure.

The continued progress and commercialization of quantum computing poses a risk to current public-key encryption methods that are likely to be deemed insecure. Toshiba’s QKD, which uses the quantum properties of light to generate secure random keys to encrypt and decrypt data, has been developed to provide protection against the power of future quantum computers.

Previously, this required network operators to invest in dark fiber throughout their networks specifically to transmit quantum information, increasing cost and time to adoption. A technique called Wavelength Division Multiplexing (WDM) has allowed QKD to operate over existing fiber networks by using spectral separation (utilizing different wavelengths of light to avoid interference) to allow quantum signals to coexist with classical data carrier signals. However, previous tests have demonstrated issues that impact the feasibility of such deployments, such as the possible number and strength of data channels, effective network distance, and the secure bit rate (sometimes called secure lock rate or SKR) achieved.

Throughout 2022 and 2023, Toshiba and Orange are conducting tests at Orange Labs in Lannion, France, to validate the coexistence of QKD and classical data signals and examine how various factors affect the efficiency of sending classical and quantum signals over existing fiber networks running classical data services.

Through testing, researchers from Toshiba and Orange demonstrated the effective co-propagation of classical and quantum signals at high secret bit rates, enabling them to coexist while still being able to transmit keys effectively at distances of up to 70 km, demonstrating outstanding results. promise for deployment in metro networks in built-up areas.

The researchers also made new findings that led to proposed updated metrics to help measure the efficiency of the system. Based on these metrics, they determined that the new QKD implementation outperformed their previous co-propagation experiments.

“This work demonstrates that we can co-propagate a quantum channel with a WDM data channel within the same fiber, without changing the WDM operational link engineering rules. The high secret key rate obtained in this configuration is very promising for the introduction of QKD in operator networks,” said Paulette Gavignet, Senior Optical Communications Specialist at Orange Innovation.

“Our commitment to security and innovation has driven us to push the boundaries of Quantum Key Distribution (QKD) solutions,” said Laurent Leboucher, Group CTO and SVP, Orange Innovation Networks. “This could be key to offering unparalleled protection for optical transport networks. Together with Toshiba, we demonstrated that it is possible to introduce new security functions in carrier networks without requiring the use of dedicated fiber. With this cost-effective approach, we are paving the way to a digital fortress, guaranteeing the security of our most valuable customer’s data.”

“The rise of quantum computing has serious implications for today’s security methods and organizations need to take action now to reduce their communication risks,” said Dr Andrew Shields, Head of Toshiba’s Quantum Technology Division. “Validating the ability of our QKD technology to protect transmissions while using existing fiber networks is a major step forward in making quantum-secure communications accessible to today’s organizations. Working with a global operator like Orange to research and improve our technology is very important, and we look forward to continuing our work in this area.”

The researchers demonstrated and evaluated a 1310-nm quantum channel multiplexed with up to 60 data channels (each carrying a 100Gb/s bit rate) in the telecom C band across a commercially available Toshiba QKD system. The ability to multiply classical data while maintaining excellent QKD performance is made possible by the system’s new design, which includes high extinction spectral filters and time domain gating used to help isolate the quantum signal and reduce noise introduced from the classical channel.

Tests were run with 30 and 60 multiplex lines of 20 km, 50 km and 70 km fiber lengths. The researchers measured the secure bit rate (SKR) at different distances to understand how effectively the system can successfully transmit a quantum key along a classical data channel, as well as the optical launch power of the data service.

Tests found that the high number of WDM channels used in this evaluation (up to 60 data channels) had minimal impact on SKR. In contrast, it was found that the optical launch power of the aggregate data channel used in the system is the most influential factor on the SKR and key delivery success. As a result, Orange and Toshiba have proposed a new metric – Co-propagation Efficiency (CE) – which can estimate the performance of a QKD system (its ability to successfully transmit secure keys with good SKR) in the co-propagation regime while considering the total classical channel power and transmission distance.

The paper demonstrates that a large number of classic data channels with high optical launch power can coexist with QKD, meaning that Toshiba’s QKD system can be used on carriers’ existing networks alongside their existing data services – drastically reducing the amount of money needed to invest and maintain QKD services, as well as implementation time.

This finding has two major implications for the continued use of QKD to secure communications against quantum computer attacks at a commercial level. First, it demonstrates that the commercially available equipment evaluated by Toshiba and Orange is successful in enabling QKD to be used more effectively in today’s fiber networks. Second, a new metric developed by the researchers, which recognizes that power (and not the number of channels) has the greatest impact on efficiency, can help operators in network and service planning.

Using these results, Toshiba, Orange, and other organizations looking to implement QKD will be in a better position to do so over existing fiber networks, reducing the overall cost of implementing today’s vital form of cybersecurity.

To read the full research paper, please visit: https://arxiv.org/abs/2305.13742

For more information on Toshiba’s QKD services and quantum technology offerings, please visit: https://www.toshiba.eu/quantum/