Chances of breaking Quantum Encryption?

Source: ACM June 2010 Vol.53.

Researchers at Toshiba Research Europe, in Cambridge, U.K., have attained a major breakthrough in quantum encryption, with their recent continuous operation of quantum key distribution (QKD) with a secure bit rate of more than 1 megabit per second over 50km of fiber optic cable.  The researchers’ feat, averaged over a 24-hour period, is 100-1,000 times higher than any previous QKD for a 50km link.  The breakthrough could enable the widespread usage of one-time pad encryption, a method that is theoretically 100% secure.

First reported in Applied Physics Letters, the QKD milestone was achieved with a pair of innovations: a unique light detector for high bit rates and a feedback system that maintains a high bit rate and, unlike previous systems, does not depend on manual set-up or adjustments.

“Although the feasibility of QKD with megabits per second has been shown in the lab, these experiments lasted only minutes or even seconds at at time and required manual adjustments,” says Andrew Shields, assistant managing director at the Cambridge lab.  ”To the best of our knowledge this is the first time that continuous operation has been demonstrated at high bit rates.  Although much development work remains, this advance could allow unconditionally secure communication with significant bandwidths.”

The QKD breakthrough will allow the real-time encryption of video with a one-time pad.  Previously, researchers could encrypt continuous voice data, but not video.

Toshiba plans to install a QKD demonstrator at the National Institute of Information and Communications Technology in Tokyo.  ”the next challenge would be to put this level of technology into the metropolitan network operation,” says Masahide Sasaki, co-ordinator of the Tokyo QKD network.  ”Our Japan-Eu collaboration is going to do this within the next few years”.