Toshiba today announced the world's highest speed quantum encryption system at the QCrypt 2014 conference, to be held on September 1 – 5. The new quantum key distribution device was installed over a 45 km optical fiber between Otemachi in central Tokyo and Koganei on the cities western outskirts, and tested over a continuous 34 day period in collaboration with Japan's National Institute of Information and Communications Technology (NICT). During this time the system achieved world records in both the total amount of secure key data (878 Gbit) and the speed of transmitting the key data (25.8 Gbit per day average) for an installed system, while remaining stable and completely autonomous.

Part of this research was performed on commission by Japan's National Institute of Information and Communications Technology (NICT) as part of their Research and Development of Secure Photonic Network Technologies project.

Quantum encryption is the new frontier in data encryption technology, providing a previously impossible level of security to the transmission of information through a network. This is made possible by exploiting the quantum nature of single photons of light to detect eavesdropping and guarantee security, a cryptographic technology known as quantum key distribution.

Toshiba has developed the world's highest speed quantum key distribution device in the laboratory, and is continuing to verify the technology using existing optical fiber lines installed in cities to provide long term stable operation. The techniques used in the field of quantum communication – the transmission and detection of single photons of light after long distance transmission through optical fibers – requires overcoming a number of technical challenges including suppression of noise and accurate alignment and synchronization.

To overcome these technical challenges Toshiba has developed automatic stabilization systems and integrated electronics to compensate, and as a result have been able to confirm 34 days of continuous unattended operation in NICT's JGN-X experimental optical fiber network located between Otemachi and Koganei in Tokyo (45 km, 14.5 dB loss). However 34 days is not the limit – the system was still operating correctly at the completion of this 34 day period, and no reasons were seen to suggest operation for much longer periods would not be possible. The daily average amount of secure key data distributed during this period was 25.8 Gbit (with 878 Gbit secure key data in total over 34 days) with an average transmission speed of 300 kbps, setting new records for both the total secure key data distributed and records for the rates per second and per day for any installed system.

Toshiba will continue performing verifications for still further long-term stable operation and increased encryption key distribution rates. The Japanese company also intends to apply its quantum encryption key distribution device to a variety of applications to verify practical usability.