Quantum Cryptography on Optical Fiber Networks

摘要: Abstract The security of conventional or classical cryptography systems relies upon the supposed (but often unproven) difficulty solving certain classes mathematical problems. Quantum represents a new paradigm for secure communications since its is based not on computational complexity, but instead laws quantum physics, same fundamental that govern behavior universe. This paper describes recent progress at BT Laboratories in development practical optical fiber-based systems. These developments include interferometric operating 1.3-μm-wavelength fiber transparency window over point-to-point links up to ∼ 50 km length and multi-user passive networks. We describe how this technology performs installed BT's public network discuss issues such as cross-talk with data channels propagating different wavelengths fiber. experimental results are used make some conclusions about likely performance parameters application opportunities technology.