China achieves quantum communication by fiber optics a thousand kilometers

May 31. (EUROPE PRESS) –

Chinese scientists have achieved two-field quantum key distribution (QKD) over a 1,002-kilometer optical fiber, a critical step towards a future large-scale quantum network.

QKD, a key method in quantum communication, allows two remote users to generate a shared key known only to them, which is used to encrypt and decrypt messages. However, its practical application faces a big bottleneck which is the distance limit, since a quantum signal cannot be amplified and the transmittance of the channel decreases exponentially with distance.

Previously, dual-field QKD was demonstrated in laboratory settings over coiled fiber up to 830 kilometers, reports Xinhua.

In a study published in the journal Physical Review Letters, Scientists from institutions including China University of Science and Technology, Jinan Institute of Quantum Technology, Shanghai Institute of Microsystems and Information Technology said that the longest distribution distance achieved was 1,002 kilometers with a secure key rate of 0.0034 bits per second.

During their experiments, the scientists developed dual-band phase estimation and ultra-low-noise superconducting nanowire single-photon detectors to suppress system noise, which impedes the production of secure keys over long distances.

The study has verified the feasibility of very-long-distance twin-field QKD and sheds light on its prospects in long-distance quantum communication, according to the University of Science and Technology of China.