Significant Advance in Secure Communication: Quantum Key Distribution Spanning Over 1,000 km Achieved

by Mateo Gonzalez
7 comments
Quantum Key Distribution

A collective effort of researchers from various Chinese organizations has shattered the existing world record by achieving an unprecedented non-relay quantum key distribution spanning 1,002 km. This significant achievement made possible with the use of twin-field QKD, ultra-low-loss fiber, and ultra-low-noise superconducting single-photon detectors, marks a crucial step towards the realization of high-speed intercity quantum communication networks.

A group of scientists from the University of Science and Technology of China (USTC) under the Chinese Academy of Sciences (CAS), in collaboration with Tsinghua University, Jinan Institute of Quantum Technology, and Shanghai Institute of Microsystem and Information Technology (SIMIT), CAS, have accomplished point-to-point long-distance quantum key distribution (QKD) over a distance of 1,002 km. This notable achievement sets a new benchmark in non-relay QKD and paves the way for high-speed intercity quantum communication. The outcome of the research was published in the Physical Review Letters journal on May 25th.

QKD, built on the principles of quantum mechanics, allows for secure key distribution between two remote parties. When coupled with the “one-time pad” encryption technique, it enables unparalleled security for private communication. However, the range of QKD has been restricted due to challenges such as channel loss and system noise.

The experiment showcased the use of twin-field QKD (TF-QKD) employing the sending-or-not-sending (SNS) protocol, thereby enhancing the correlation between key rate and channel transmittance from a linear η to its square root η. This, in turn, permits a significantly greater secure distance compared to conventional QKD protocols.

The research team, in association with Yangtze Optical Fibre and Cable Joint Stock Limited Company (YOFC), used ultra-low-loss fiber founded on pure silica core technology to achieve long-distance QKD, registering a maximum attenuation of 0.16 dB/km. SIMIT pioneered ultra-low-noise superconducting single-photon detectors. The implementation of multiple filters at 40 K and 2.2 K temperatures helped suppress dark counts caused by thermal radiation, reducing the noise of the single-photon detectors to around 0.02 cps. Additionally, the team developed a dual-band phase estimation scheme to counter spontaneous Raman scattering noise, bringing the system noise down to less than 0.01 Hz.

Using these technological breakthroughs, the team achieved TF-QKD over a record-breaking distance of 1,002 km, with a key rate of 0.0034 bps. This work not only confirms the viability of the SNS-TF-QKD scheme at incredibly long distances but also shows that this protocol can deliver high key rates in numerous practical circumstances.

This research breakthrough holds considerable importance for the progress of secure quantum communication. It heralds new opportunities for long-distance quantum key distribution and sets the stage for the establishment of high-speed intercity quantum communication networks.

Reference: “Experimental Twin-Field Quantum Key Distribution over 1000 km Fiber Distance” by Yang Liu, Wei-Jun Zhang, Cong Jiang, Jiu-Peng Chen, Chi Zhang, Wen-Xin Pan, Di Ma, Hao Dong, Jia-Min Xiong, Cheng-Jun Zhang, Hao Li, Rui-Chun Wang, Jun Wu, Teng-Yun Chen, Lixing You, Xiang-Bin Wang, Qiang Zhang and Jian-Wei Pan, 25 May 2023, Physical Review Letters.
DOI: 10.1103/PhysRevLett.130.210801

Frequently Asked Questions (FAQs) about Quantum Key Distribution

What is the major breakthrough achieved by the Chinese researchers?

The researchers from various Chinese institutions have achieved a significant breakthrough by setting a new world record for non-relay Quantum Key Distribution (QKD) over a distance of 1,002 kilometers.

What does this achievement mean for the future of quantum communication?

This achievement marks a significant advancement towards the realization of high-speed intercity quantum communication networks. It opens up new possibilities for long-distance quantum key distribution and sets the stage for the establishment of these networks.

What technologies were used to achieve this breakthrough?

The research team used a combination of twin-field QKD (TF-QKD), ultra-low-loss fiber based on pure silica core technology, and ultra-low-noise superconducting single-photon detectors to achieve this milestone.

What’s the significance of twin-field QKD (TF-QKD)?

Twin-field QKD, which uses the sending-or-not-sending (SNS) protocol, enhances the relationship between the key rate and channel transmittance from a linear η to its square root η. This allows for a significantly greater secure distance compared to traditional QKD protocols.

Who were the key collaborating institutions involved in this achievement?

The key collaborators in this breakthrough include the University of Science and Technology of China (USTC) under the Chinese Academy of Sciences (CAS), Tsinghua University, Jinan Institute of Quantum Technology, and Shanghai Institute of Microsystem and Information Technology (SIMIT), CAS.

Was this research published in a scientific journal?

Yes, the result of the research was published in the Physical Review Letters journal on May 25th, 2023.

What challenges did the researchers overcome to achieve this distance in QKD?

The researchers overcame the challenges of channel loss and system noise, which have historically limited the distance of Quantum Key Distribution (QKD). They also developed a dual-band phase estimation scheme to counter spontaneous Raman scattering noise.

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7 comments

ScienceGeek101 June 14, 2023 - 3:02 pm

Still trying to wrap my head around the tech details, but it’s clear this is big news for quantum comms. a new world record, eh? impressive indeed!

Reply
DreamerDiana June 14, 2023 - 4:14 pm

I’m still grappling with the basics of quantum physics, but this news? it’s like science fiction becoming reality! mind-blowing, really.

Reply
JakeRadford June 14, 2023 - 4:56 pm

Wow! 1002 km for QKD, thats just mind-blowing! The future of secure communication is here, folks!

Reply
QuantumQurious June 14, 2023 - 7:47 pm

So stoked to see these advancements in quantum tech. amazing what the twin-field QKD and ultra-low-loss fiber can achieve!

Reply
PhotonFanatic June 14, 2023 - 11:32 pm

This is the kind of breakthrough I love seeing in quantum research! they’ve raised the bar with this one. the future is quantum.

Reply
CyberSecEnthu June 15, 2023 - 3:29 am

Can you imagine, a high-speed intercity quantum network? The possibilities for secure comms are just astounding. Kudos to the Chinese researchers.

Reply
FuturisticFred June 15, 2023 - 3:54 am

Great step towards the future! Really shows that our communication networks could be on the verge of a quantum leap, pun intended 😉

Reply

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