The range of quantum cryptography systems using optical fibers is limited to roughly 30 km because amplifiers cannot be used. A fully operational system for quantum cryptography based on the transmission of single photons in free space under daylight conditions has been demonstrated. The feasibility of a global system for quantum cryptography based on a network of ground stations and satellites is discussed.
© 1996 Optical Society of America
B. C. Jacobs and J. D. Franson, "Quantum cryptography in free space," Opt. Lett. 21, 1854-1856 (1996)