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China opened a milestone in quantum technology, Einstein laughed

Science 2018-02-25 12:14:32 25

Einstein once said that quantum theory, if established, would have to have a "spooky action at a distance." He refuses to admit that the way the universe works is so weird that it looks so random. In particular, he laughed at the idea of ​​"quantum entanglement": particles that are independent of each other can be completely "entangled" together, and observing one of them can affect other particles instantaneously, no matter how far apart they are. He was so annoyed at the uncertainty of the introduction of quantum theory and compared it to the consequences of casting God's dice.

However, China has received many disruptive and remarkable achievements in the field of quantum communication. Cai Linge said in an interview that Einstein will be surprised. Because these quantum mechanics theory, such as quantum entanglement, have now really come into practical use, which is beyond Einstein's expectations.

On August 16, 2016, China's "Mozi" quantum satellite was launched. In December 2017, Pan Jianwei, chief scientist of China's Quantum Satellite Project, was selected as one of the ten science figures of the year in the journal Nature. The United States, European countries, top scientific research institutions and science and technology giant enterprises, in-depth study of quantum technology in full swing to meet the quantum technology breakthrough revolution.

Global tech giant competes for Quantum Supremacy </ strong>

The so-called quantum supremacy is a new word invented by Caltech physicist John Preskill. Popular interpretation is: the supercomputer's current computing power is equivalent to a quantum computer with 5 to 20 qubits, but when the quantum chip quantum bits to reach more than about 49, the quantum computer's ability to completely supercomputer thrown Behind.

Quantum computing leader - Google announced in April 2017 the introduction of 49 qubits processor. John Martinis, Google's chief scientist, has said publicly that in order to take the lead in "Quantum Supremacy," his team is using the 49-bit quasi-bit simulation system to overcome the classic computer problems that can not be solved.

Six months later, IBM of the United States took the lead in announcing the successful development of a 20-qubit processor and the introduction of a 50-qubit "quantum computer" prototype. It is expected to launch the first quantum computing application in the financial sector by 2021, objectively Presented a challenge to Google's "quantum hegemony" algorithm. On the other hand, IBM has yet to announce the detailed performance and test results of the Quantum Computing Prototype.

Subsequently, Microsoft also introduced its general quantum computing research and development program as well as the full stack development and simulator, although not yet publicly disclosed hardware devices. Companies such as IonQ, Quantum Circuits and RIKEN have also invested in hardware development, but they have not yet announced their R & D results.

Michael Mayberry, Intel vice president and president of Intel Research Institute, said in a written interview with CBNQ that quantum computing is the ultimate goal of parallel computing. At present, quantum computing is still in its infancy and the problem of solving the project scale may still need 5 ~ 7 years. From a commercial point of view, quantum computing may need 1 million or more qubits to have practical value.

Both startups D-Wave and Japan's NTT achieved 2048 physical qubits, but neither of them completed the full capabilities of general-purpose quantum computation and were only suitable for solving optimization problems, molecular dynamics, deep learning training and reasoning.

Last year, technology giants vied with each other to announce a breakthrough in the number of qubits, and further it was to look at indicators such as quantum entanglement manipulation accuracy, coherence characteristics and logic gate fidelity. This is the main difficulty. It is foreseeable that the competition for quantum computing in 2018 will continue to escalate.

According to Shi Yunyun, chief scientist of Aliyun Quantum Laboratory and Zhiyang Yun, deputy director of Zhijiang Laboratory, he is optimistic that the "quantum hegemony" will be realized in 2018, while predicting that several major world-class technology companies will face the quantum hegemony melee battle and play the annual quantum drama.

China Milestone for Quantum Communications </ strong>

China University of Science and Technology Professor Pan Jianwei and his colleague Peng Chengzhi and other research team, the joint Shanghai Institute of Technical Physics Wang Jianyu Research Group, Institute of Micro-satellite Innovation, Institute of Optoelectronics Technology, National Astronomical Observatories, Purple Mountain Observatory, Nanjing Astronomical Instrument Co., Ltd., National Space Science Center, etc. With the support of the CASS leading science and technology project of space science and the use of "Mozi" quantum science experimental satellite, the first successful international quantum key distribution from the satellite to the ground and from the ground to The quantum teleportation of the satellite. Both results were published online at the same time on August 10, 2017 in the journal Nature, an internationally acclaimed academic journal.

This is the first in the world to take the lead in achieving thousands of kilometers of stars in the two-way quantum entanglement distribution and quantum mechanics of non-locality of the research results published in the "Science" magazine, our scientists use "Mozi" quantum satellite space Two other major breakthroughs in quantum physics research. At this point, "Mozi" quantum satellites ahead of schedule and the full realization of all three major established scientific goals.

One of the scientific goals of "Mozi" quantum satellites is the high-speed quantum key distribution of stars. Quantum key distribution experiment uses the method of transmitting quantum signals by satellite and receiving by the ground. When the "Mozi" quantum satellite transits, it establishes an optical link with Hebei Xinglong terrestrial optical station with the communication distance from 645 km to 1200 km. At a transmission distance of 1200 km, the transmission efficiency of the satellite quantum key is 20 orders of magnitude higher than that of the same-distance terrestrial fiber channel. On average, the quantum decoy state light source transmits 40 million signal photons per second, and an orbit docking experiment can generate a 300 kbit security key with an average coding rate of up to 1.1 kbps. This important achievement has laid a solid technical foundation for the establishment of a worldwide quantum secure communications network. Based on the distributed quantum key distribution of the star, using the satellite as a trusted relay can realize the key sharing of any two points on the earth and extend the quantum key distribution coverage to cover the whole world. In addition, by interconnecting the quantum communication ground station and the inter-city optical fiber quantum confidential communication network, it is possible to construct a world-wide integrated secure communication network.

For this reason, reviewers of Nature magazine praised the achievement of the Earth's quantum key distribution as "admirable achievements" and "a milestone in the field" and asserted "there is no doubt that quantum information, space science, etc. will be elicited. Field scientists and the general public, and led to a very wide coverage of the public media. "

Earth's quantum teleportation is one of the scientific goals of the "Mozi" quantum satellite. Quantum teleportation adopts the mode of ground-launched entangled photons and received in the sky. When the "Mozi" quantum satellite transits, it establishes an optical link with the Tibet Ali Earth Station at an elevation of 5100m. Ground light sources produce 8,000 cases of quantum teleportation per second, and the ground transmits entangled photons to the satellites. Experimental communication distances range from 500 km to 1,400 km. All six states to be transmitted are above the classical limit with greater than 99.7% confidence. Suppose that repeating this work in the same length of fiber requires 380 billion years (20 times the age of the universe) to observe one case. This important achievement laid a solid technical foundation for the future research on space-scale quantum communication networks, as well as the research on space quantum physics and quantum gravitation experiments.

In response, reviewers at Nature magazine praised it as "these results represent a major breakthrough in the ongoing exploration of long-range quantum communications." "This goal is very new and challenging. It represents the reality of quantum communication solutions Major progress ".

And Einstein's point of view is similar, there are still many voices of doubt, and even spread some rumors for quantum communication, said the modern quantum technology as "metaphysics", "scam."

However, facts speak louder than words. After a hundred years of scientists going forward and onwards, seemingly difficult to understand the theoretical foundation of quantum mechanics has been very deep, and the same as the theory of physics building a more solid base. Quantum communication is a model for the global scientific community to put these theories to practical use, and China's quantum satellite project is one of the outstanding representatives.

Strong theory and proven </ strong>

In theory, quantum mechanics, which originated in the early part of the last century, uses probability to describe physical phenomena and does indeed seem "mysterious": the particles on the microscopic scale are "there" here and there, and "may" move in both directions at the same time; Particles can also be entangled with each other - in some way instantly perceived remotely, affecting each other.

After Einstein, Bohr, Heisenberg, Schrodinger and other scientific giants continue to improve, quantum mechanics theory initially formed and continued development. This seemingly "unreasonable" theory has gained more and more experimental support and has spawned many major inventions - atomic bombs, lasers, transistors, nuclear magnetic resonance, and global positioning satellite systems. When the EU announced in 2016 that quantum technology as the new flagship research project, the above result was called "the first quantum revolution."

The quantum information technology is the latest development of quantum mechanics, representing the emerging "second quantum revolution", the most representative of which is quantum communication and quantum computing.

Quantum communication mainly solves the communication security problem. Traditional information encryption technology relies on the complexity of mathematical algorithms, but with the rapid increase of computing power, complex encryption algorithms may also be cracked. Based on the "quantum key" of quantum communication, from the fundamental objective laws of physics, so that "absolutely safe."

For example, the quantum itself is the smallest unit, with a light quantum transmission of information, eavesdroppers can not be divided into "half a quantum" to obtain information; Quantum mechanics "uncertainty principle" is bound by the eavesdropping behavior itself, as long as someone tries to measure Quantum, the quantum state automatically changes, "report" eavesdropping behavior; In addition, the non-clonality of the quantum determines the eavesdropper can not accurately copy the quantum information.

Therefore, the use of quantum made of "key" to transmit information, eavesdropping is bound to be found, and encrypted content can not be deciphered.

Quantum communication has long been a hot area in academia. In 1997, an essay on "Experimental Quantum Teleportation" was published in the journal Nature. After being peer reviewed, he was also selected as one of the "authors of the 21st Century Classic in a Century of Physics." Academician Pan Jianwei is one of the authors. He was named "Nature" magazine's top ten scientific figures this year, also demonstrated that quantum communication has drawn great attention from the international scientific community.

In practice, from the United States to Europe, from state-of-the-art research institutes to technology giant, the research on quantum technology has been launched in full swing. The new round of science and technology competition triggered by the quantum revolution is in full swing. The quantum communication has also been gradually applied from the theoretical conception to the practical application. The breakthrough made by China in this respect has attracted worldwide attention.

In June 2017, using the "Mozi" Quantum Science Experimental Satellite, the Chinese scientific research team took the lead in the world in successfully achieving the bidirectional two-way quantum entanglement distribution of 1000-kilometer stars. This achievement was published in the form of a cover paper by the United States "Science" magazine and was awarded as "a major technological breakthrough that combines the potential practical applications with the importance of basic scientific research."

The end of September 2017, the world's first quantum secure communication trunk - "Beijing-Shanghai trunk line" was officially opened, combined with "Mozi" satellites, the Chinese Academy of Sciences Bai Chunli and Dean of the Austrian Academy of Sciences, Quantum Communications, authoritative international scientist Anton Cai Linge achieved the world's first intercontinental quantum confidential communications.

Cai Linge interviewed Xinhua News Agency reporters earlier said that China has made remarkable achievements in the field of quantum communications. "Einstein will surely be surprised," he said with a laugh. "Because these quantum mechanics theories, such as quantum entanglement, have really come into practical use, it is beyond Einstein's expectations."

The "Beijing-Shanghai Main Line" is a backbone of quantum communications that connects Beijing, Shanghai, Jinan and Hefei. It has a total length of 2,000 kilometers and can meet the key distribution business needs of tens of thousands of users. Through this route, Bank of Communications, Industrial and Commercial Bank of China and Alibaba Group have also implemented applications such as quantum cryptography for remote data transmission between Beijing and Shanghai.

Cai Linge predicts that in the next 20 years, quantum communication technology is expected to be widely used all over the world. In the future, "quantum Internet" may even emerge, and quantum computers, quantum internet and quantum satellites will be used together to lay the foundation for new technologies in the future.

In February 2018, the CAS Meeting of Quantum Information and Quantum Technology Innovation Institute (hereinafter referred to as "Quantum Innovative Research Institute") and the 2018 Annual Work Conference were held in Hefei. The latest achievements of quantum computers were released: in the direction of superconducting quantum computing 11-bit cloud access superconducting quantum computing services, users can upload test run a variety of quantum computing circuit code, and download the relevant operating results; in the direction of semiconductor quantum computing based on quantum dot quantum chip Deutsch Jozsa quantum algorithm demonstration, implementation Multi-quantum bit logic gates.

At this conference, the Institute of Quantum Innovation released the major scientific and technological goals for the next five years, including the development and launch of several micro and nano quantum satellites and the establishment of the quantum cryptography satellite service network.

It is foreseeable that there will be further breakthroughs in quantum theory and its technical practice in the future. This time, Einstein may no longer be surprised, but smiled happily for technological progress.

Quote 1. "Technology giant compete for" quantum hegemony "" Chinese team "quantum communication rise"

Quote 2. "Mo Zi" Quantum Science Experimental Satellite successfully fulfilled all the pre-set scientific goals "