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On December 4, 2020, the China University of Science and Technology announced that a research team led by Pan Jianwei had built a prototype of quantum computing with 76 photons and 100 modes, “Nine Chapters”. This achievement allowed our country to successfully reach the first milestone in quantum computing research: the superiority of quantum computing.
Just a month later, Pan Jianwei and others made another breakthrough and built the world’s first satellite-earth quantum communication network!
Earlier this morning, the China University of Science and Technology announced:
Pan Jianwei and others built the world’s first wide-area quantum communication network that integrates more than 700 terrestrial fiber optic quantum key distribution links (QKD) and two satellite-to-ground high-speed free space QKD links, achieving a land area of 4,600 kilometers. Large-scale multi-user quantum key distribution for satellite-terrestrial integration.
So far, China has built the prototype of a wide-area quantum communication network that integrates the world and the earth.
“Only the deaf can’t figure it out”
On January 6, 2020, the research team’s article was published in the internationally renowned academic journal Nature, titled An integrated space-to-earth quantum communication network of more than 4,600 kilometers (a space-to-earth quantum communication network of more than of 4,600 kilometers).
For this study, the Nature reviewers stated:
This is the largest and most advanced quantum key distribution network on the planet, and it is also a great engineering achievement in the field of quantum communication.
Information from nature shows that the author of the article is from the Department of Modern Physics, Faculty of Physics, China University of Science and Technology, Hefei National Laboratory for Microscale Materials Science, Border Innovation Center for Quantum Technology and Quantum Information from the Chinese Academy of Sciences, China Cable Network Co., Ltd., Jinan Quantum Technology Research Professor Pan Jianwei is one of the corresponding authors of the Key Laboratory of Space Active Optoelectronic Technology, Shanghai Institute of Technical Physics, Chinese Academy of Sciences.
In cryptography, the key can complete the encryption, decryption, and verification of the integrity of the secret information. In fact, since human beings have used language, the technology of encrypting information with keys has continually developed.
In 1984, the physicist Bennett and the cryptographer Brassard proposed the first quantum key distribution protocol (BB84 protocol) based on the quantum mechanical measurement principle, aimed at increasing the distance of secure communication and improving security. The quantum key distribution (QKD, or quantum key distribution) proposed according to this protocol can provide unconditional and secure shared keys for users that separate two places, and fundamentally guarantee the security of the keys.
As early as the 1990s, an article jointly published by IBM, the University of Montreal in Canada, and the University of California at Los Angeles introduced a device and protocol to implement quantum key distribution (QKD).
In short, the function of this device and protocol is: two users who do not share secret information at first exchange random quantum transmissions made up of very faint polarized light reflections, and then publicly discuss the transmit and receive versions of the transmission. If eavesdropping is small enough, random shared information can be extracted in the send and receive versions.
This whole process is based on the uncertainty principle of quantum physics, which can withstand any third party with unlimited computing power.
In fact, this is the process of the world’s first QKD experiment, the line is only 32 cm. Undoubtedly this is a historical event of quantum encrypted communication, but limited to the technology at the time, one of the jokes of the people is that “only the deaf cannot decipher it.”
The world’s first satellite-Earth quantum communication network
Yet it is one of the charms of science from not being understood at first to astonishing the world later.
In recent years, quantum encryption communication has developed rapidly. In China, the name of Professor Pan Jianwei has been “strongly linked” to this field. Advances made by his team include:
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At 1:40 am on August 16, 2016, at the Jiuquan Satellite Launch Center, the Long March 2D carrier rocket successfully launched the world’s first experimental quantum science satellite, “Mozi.” As a result, China became the first country in the world to realize quantum communication between space and earth, and China’s secure quantum communication and science experiment system integrating the world and earth was also established.
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On September 29, 2017, the Chinese Academy of Sciences announced the official opening of the world’s first secure quantum communication trunk, the “Beijing-Shanghai trunk line.” Since then, the quantum communication backbone that connects Beijing and Shanghai and crosses Jinan and Hefei for more than 2,000 kilometers will promote the large-scale application of quantum communication in the fields of finance, government affairs, national defense and electronic information.
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An article published in February 2020 showed that it has surpassed long-distance independent laser phase interference technology and realized the real-environment fiber’s dual-field quantum key distribution of the order of 500 kilometers, which a once again refreshed the world record for quantum key distribution transmission distance.
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A paper published in June 2020 showed that 1,120 kilometers of non-entangled quantum key distribution have been performed, which is the first time in the world to perform entanglement-based quantum key distribution at a thousand kilometer level.
China’s research progress in this field is obvious to everyone, but as the paper notes:
A global QKD network should be a practical (not just theoretical) secure and reliable QKD network that can be used by users around the world. In principle, quantum repeaters can provide a viable solution for such a global network, but the current level of technology is not sufficient to implement such a network.
According to the introduction of the China University of Science and Technology, according to the communication channel, the quantum key distribution is mainly divided into two types: terrestrial fiber (more stable channel, less susceptible to environmental factors, more suitable for interurban scenarios short distance) and free space (mainly satellite transit, it is suitable for long distance situations and limited fiber resources such as target movement).
Thus:
The combination of terrestrial fiber and free space can generate a large-scale, full-coverage global quantum communication network.
The focus of the research team isCombining the “Mozi” with the “Beijing-Shanghai trunk line”, it integrates more than 700 terrestrial fiber optic quantum key distribution links and 2 high speed QKD links in free space from satellite to ground.
Without a doubt, this is the first in the world!
In the end, a large-scale multi-user quantum key distribution was built with a land area of 4600 kilometers.
[Fuente de la imagen: Universidad de Ciencia y Tecnología de China]
It is understood that the team has conducted more than two years of stability and security testing, standardization research, and application demonstrations in different fields such as government affairs, finance, and power.
In a typical satellite transmission, the rate of distribution of the quantum key from the satellite to the ground averages 47.8 kilobits per second, which is more than 40 times higher than before.
In addition, the work also states that the channel loss of this network is equivalent to the channel loss between a geosynchronous satellite and the ground, that is, it is possible to build more functions and ultra-long quantum links through a geosynchronous satellite.
World-Earth Integrated Wide Area Quantum Communication Network Is Near
In this image, it is Pan Jianwei, the quantum physicist and academic at the Chinese Academy of Sciences who created the world’s first experimental quantum science satellite, “Mozi.” In a 2016 interview, Nature referred to him as the “pioneer of quantum space from China.”
In November 2020, at the Tencent Science WE conference, Professor Pan Jianwei delivered a speech titled “New Quantum Revolution.”
He said that the interaction of information has been and will always be accompanied by human evolution and social development, in this process two things are very important, one is the efficiency of information exchange and the other is the protection of privacy. The answer given by Professor Pan Jianwei is quantum communication and quantum computing on how to transmit information efficiently and safely.
Talking about the future of China’s quantum communications, he said:
After 10-15 years of hard work, we hope to be able to fully develop a wide-area quantum communication network technology system that integrates heaven and earth.
Today, the feasibility of building an integrated quantum communication network has been successfully verified. Naturally, the technological system of the integrated wide-area quantum communication network that the Chinese scientific team hopes to achieve is not far off.
Reference source:
https://www.nature.com/articles/s41586-020-03093-8
https://mp.weixin.qq.com/s/-xhFdYqR7YB72uDgMp3VLQ
https://baijiahao.baidu.com/s?id=1688181762796479529&wfr=spider&for=pc
Red Lei Feng Red Lei Feng Red Lei Feng(Public account: Lei Feng Net)
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