World-Record Quantum Key Distribution Bit Rate Realizing Ultra-Secure Networks

Dramatic improvement in the performance and utility of quantum key distribution (QKD) will realize next-generation secure networks. Toshiba has increased the secure bit rate 100-fold, achieving values of 1.02 Mbits/s and 10.1 kbits/s over 20 km and 100 km of optical fiber, respectively. These are world-record values(*) and the first time that the bit rate has exceeded 1 Mbit/s under the unconditionally secure condition.

This advance stems from a recent invention by Toshiba Research Europe Limited (TREL) in the field of single photon detection technology. The self-differencing avalanche photodiode allows a 100-fold increase in the system clock rate and a 5 000-times higher maximum count rate.

We also participated in a field trial of a small-scale QKD network as part of the EU-funded SECOQC Project. Operating QKD in real telecom networks, as opposed to the private point-to-point links used previously, is essential to broaden applicability and lower cost. The TREL system (upper figure) operated stably and reliably during the month-long deployment. Following the successful conclusion of SECOQC, ETSI has launched a standardization initiative for QKD.

The recent increase in bit rate will allow QKD to be applied to much larger scale networks in the future. Higher bit rates are important because the key material must be shared between users in such networks. It will also extend the range of individual links and allow highbandwidth unconditionally secure communications using a one-time pad.

(*) As of October 2008 (as researched by Toshiba)

SECOQC: Development of a Global Network for Secure Communication based on Quantum Cryptography
ETSI: European Telecommunication Standards Institute

QKD system used in the EU field trial

Comparison of final key rates for unconditionally secure QKD