Quantum Cryptographic Key Distribution from Single-Photon Emitter at World-Record Distance of 50 km achieved in Japan

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.