High-speed Quantum Cryptography over Global Distances
Quantum key distribution (QKD) has been implemented in metropolitan area networks around the world. For application in metropolitan QKD networks, we further develop a high-speed, fiber-integrated and telecom-compatible quantum communication system, based on continuous variables. The quantum channel is operated within a dense wavelength-division multiplexing grid. We show that our quantum communication system is robust and practically unaffected by the presence of a telecom carrier signal on a neighboring channel. Optical satellite communication lends itself to interconnect such metropolitan networks over global distances using similar technology. For this purpose, existing Laser Communication Terminals (LCTs) can be upgraded to QKD application. We have performed first satellite measurement campaigns to validate this approach.