Quantum mechanics provides methods of encryption that are secure from eavesdropping attacks against the quantum channel. The National Institute of Standards and Technology (NIST; Gaithersburg, MD) has developed a high-speed quantum key distribution test bed incorporating both free-space and fiber systems.

In this video, Joshua Bienfang of NIST talks about the quantum cryptographic system that operates over a 1.5-kilometer free-space link on the NIST campus. These quantum communication systems rely on cryptographic key known to both the sender (Alice) and receiver (Bob). Transmitting at 1.25 gigahertz, any intrusion into the system would be detected by comparing data at the transmitting and receiving end.

Bienfang is a physicist in the Electron and Optical Physics Division at NIST, where he works on quantum cryptography.

Related publications:
Quantum key distribution at GHz transmission rates
Alessandro Restelli, Joshua C. Bienfang, Alan Mink, and Charles W. Clark
Proceedings of SPIE Volume 7236 (2009)

High speed quantum key distribution system supports one-time pad encryption of real-time video
Alan Mink, Xiao Tang, LiJun Ma, Tassos Nakassis, Barry Hershman, Joshua C. Bienfang, David Su, Ron Boisvert, Charles W. Clark, and Carl J. Williams
Proceedings of SPIE Volume 6244 (2006)