Unforgeable Quantum Tokens Delivered Over Fiber Network The demonstration redeemed secure tokens across 10 kilometers Looking ahead, Ishii’s group is working to extend the length of optical fiber that quantum tokens can be transmitted, which could stretch to 50 km before the quantum data becomes unstable. Other targets include speeding up the transmission and reception of the tokens, and the development of a QKD device that does not require dedicated optical fiber for the quantum channel. Besides financial applications, NEC sees quantum tokens being used for cryptographic communications by large companies and government agencies. So, as a business, NEC is considering providing both the platform for the technology and quantum token application services. “Although some customization of the platform will be necessary to suit the application, we believe the technology is basically complete and ready for commercial use now,” says Ishii.