Institute for Nano Quantum Information Electronics, the University of Tokyo. Fujitsu Laboratories and NEC today announced that they have achieved quantum cryptographic key distribution at a world-record distance of 50 km using transmission from a single-photon emitter. This result was the product of the three-way collaboration between the University of Tokyo, Fujitsu, and NEC, and represents a milestone in quantum key distribution because it combines a single-photon emitter, which is ideal for optical transmission bands, with a prototype of a practical quantum cryptography system. Experimental success at a practical level with a single-photon emitter brings one step closer the practical use of quantum cryptography in the 1.5 µm band, which is most desirable for long-distance data transmissions.
This research can be considered the first in the world to bring together work in quantum-dot optical devices with quantum information technology. Future work will focus on making systems using single-photon emitters more efficient, with the goal of practical implementations in 5–10 years.
