Los Alamos develops quantum crypto system By Chappell Brown Electrical Engineering Times (08/23/01, 1:06 p.m. EST) LOS ALAMOS, N.M.  Engineers at Los Alamos National Laboratory have developed what they believe is a practical quantum cryptographic system. The system features two portable units that can encrypt and decrypt information transmitted via photons. Experiments have shown that encryption keys can be sent via free-space transmission at distances of up to 6 miles. The system could be used to ensure safe communications between satellites. Quantum cryptography uses the fundamental law of quantum mechanics: Any observation of a system changes its state. Since photons are elementary particles, they are subject to the law. If a third party attempts to "tune in" to the encrypted transmission, the quantum state of the photons will change, allowing the eavesdropping to be detected. Quantum Computation/Cryptography at Los Alamos homepage http://qso.lanl.gov/qc/