The company, which hails this as a significant advance towards building a global quantum internet, says previous commercial quantum key distribution systems were limited to 100-200km of fibre.
“This is a very exciting result,” said Mirko Pittaluga, a Toshiba research scientist in Cambridge (pictured). “With the new techniques we have developed, further extensions of the communication distance for QKD are still possible and our solutions can also be applied to other quantum communications protocols and applications.”
Toshiba said the breakthrough will enable long distance quantum-secured information transfer between metropolitan areas and said it is a major advance towards building the future quantum internet.
Andrew Shields, head of the quantum technology division at Toshiba Europe, said: “This latest advance extends the maximum span of a quantum link, so that it is possible to connect cities across countries and continents, without using trusted intermediate nodes. Implemented along with satellite QKD, it will allow us to build a global network for quantum secured communications.”
The technique will allow highly secure communications across the globe, using a global network of quantum computers connected by long distance quantum communication links.
Toshiba says this is the latest step in one of the most difficult technological challenges in building the quantum internet, the problem of how to transmit quantum bits over long optical fibres.
“Small changes in the ambient conditions, such as temperature fluctuations, cause the fibres to expand and contract, thereby scrambling the fragile qubits, which are encoded as a phase delay of a weak optical pulse in the fibre,” said the company.
Taro Shimada, Toshiba’s chief digital officer, said: “Our vision is a platform for quantum information technology services, which will not only enable secure communication on a global scale, but also transformational technologies such as cloud-based quantum computing and distributed quantum sensing.”
The details of the advancement are published in the scientific journal, Nature Photonics. The work was partially funded by the European Union through the H2020 project, OpenQKD. Corning supplied the fibre for the study.
This latest development follows the announcement last year that BT and Toshiba had installed the UK’s first industrial quantum-secure network.
