-Accelerating technological studies for long-distance QKD toward the realization of the quantum internet-

Toshiba Corporation (Headquarters: Kawasaki, Kanagawa, Japan; President and CEO: Taro Shimada; hereinafter “Toshiba”) and LQUOM Inc. (Headquarters: Yokohama, Kanagawa, Japan; CEO: Kazuya Niizeki; hereinafter “LQUOM”) have entered into a joint research agreement to explore the extension of quantum key distribution (QKD) over long distances. This collaboration forms part of broader efforts to build long-term technological foundations and an ecosystem toward the realization of the quantum internet. In this joint research project, the companies will study the technical challenges and feasibility of extending next-generation QKD over long distances by combining QKD systems with quantum repeater systems, a key technology expected to underpin future quantum communication networks.

QKD is attracting increasing attention as a secure cryptographic communication technology that leverages the principles of quantum mechanics and is theoretically immune to decryption even by quantum computers. Efforts toward its social implementation are actively underway across various fields, including finance, healthcare, energy, and inter–data center communications. However, several technical challenges remain in achieving longer transmission distances, higher speeds, and large-scale network deployment.
Quantum repeaters are a key technology that enables long-distance transmission of quantum states without degrading them. They are therefore regarded as an essential component for extending the reach of quantum communications, including QKD, and are expected to become a fundamental technology for future quantum networks.

This joint research project will be conducted from March 2026 to March 2027. The two companies will evaluate optimal combinations of QKD schemes and quantum repeater architectures—each of which has multiple possible approaches—from both performance and implementation perspectives to identify promising methods for realizing long-distance QKD. Toshiba will primarily study QKD protocols and architectures, while LQUOM will focus on quantum repeater system architectures.

Through this collaboration, both companies aim to utilize the knowledge gained to further advance research and development in the field of quantum communications—including QKD and the quantum internet—and contribute to the realization of a secure and reliable next-generation information infrastructure.

Figure: Long-distance quantum key distribution using a quantum repeater system

◆About Toshiba

Toshiba has been conducting research and development on QKD since 1999 and has achieved numerous milestones in key distribution speed and communication distance [1,2]. Since 2020, Toshiba Digital Solutions Corporation has been commercializing QKD technologies [3]. Alongside advanced research and development, Toshiba Digital Solutions has also carried out various demonstrations and proof-of-concept projects. The company is also pursuing foundational research on technologies for future quantum networks and the quantum internet, including entangled photon sources and quantum repeaters [4]. To accelerate the social implementation of these technologies through ecosystem development, Toshiba invested in LQUOM via its corporate venture capital (CVC) arm in 2023.

[1] https://www.global.toshiba/ww/news/corporate/2018/09/pr1101.html
[2] toshiba.eu/pages/eu/Cambridge-Research-Laboratory/toshiba-announces-breakthrough-in-long-distance-quantum-communication
     Nature Photonics 15, 530–535 (2021). https://www.nature.com/articles/s41566-021-00811-0
[3] https://www.global.toshiba/ww/news/corporate/2020/10/pr1901.html
[4] Commun Phys 3, 121 (2020). https://www.nature.com/articles/s42005-020-0390-7
 

◆About LQUOM Inc.

LQUOM is a startup originating from Yokohama National University that develops quantum communication systems, quantum repeaters, and related technologies aimed at realizing the quantum internet. For secure quantum communication over long distances, signal relaying is essential, and specialized quantum repeaters are required to build quantum communication networks. LQUOM possesses core technologies necessary for the development of quantum repeaters and aims to realize the practical deployment of the quantum internet—an absolutely secure next-generation network—through the development of quantum repeater systems based on entanglement-based approaches.

https://lquom.com/en/