Chinese scientists realize high-quality quantum key distribution

BEIJING, Feb. 6 (Xinhua) -- Chinese scientists have developed a high-performance quantum key distribution method that brings a telecom fiber-based quantum communication network one step closer.

The researchers from the University of Science and Technology of China and Tsinghua University realized, for the first time, experimental mode-pairing quantum key distribution, Monday's edition of Science and Technology Daily reported.

Quantum key distribution is based on a physical property in quantum mechanics which makes it impossible to create an independent and identical copy of an arbitrary unknown quantum state, thus providing an unhackable way to exchange encrypted messages between remote users.

Quantum key distribution networks, based on telecom fibers, have been implemented on metropolitan and intercity scales in China. However, the exponential decay of the key rate with respect to the transmission distance has been considered a bottleneck, said the researchers.

In the new study published in the journal Physical Review Letters, the researchers used two independent off-the-shelf lasers to demonstrate an easier, cost-saving way to realize significant key-rate improvement when dealing with metropolitan and intercity distances.

The key rate performance was shown to be boosted by three orders of magnitude via 304 km commercial fiber and 407 km ultralow-loss fiber, according to the study.

The ready-to-implement high-performance method is likely to be widely used in future intercity quantum communication networks, said the researchers.