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The results of the "Nine Chapters" and "Zuchong No. 2" have made China the only country that has achieved "quantum computing superiority" in both physical systems, and firmly established the status of the international first square of quantum computing research.
Wen | Xu Haitao, Zhou Chang, and Chen Nuo, reporters of the "Lookout" news weekly
On May 26, 2015, Pan Jianwei commissioned equipment in the laboratory of the Shanghai Research Institute of the University of Science and Technology of China Zhang Duanzhao / This journal
◇ The results of "Nine Chapters" and "Zu Chong No. 2" have made China the only country that has achieved "quantum computing superiority" in both physical systems, and firmly established the status of the international first square of quantum computing research
In August 2016, the "Mozi" quantum science experimental satellite was launched, marking China's leading position in global quantum communication research. In December 2020, the University of Science and Technology of China announced that Pan Jianwei and others at the university successfully built a 76-photon quantum computing prototype "Nine Chapters", making China the second country in the world to achieve "quantum computing superiority". In October 2021, the prototype of quantum computing with 113 photons in 144 mode "Jiuzhang-2" was announced.
From "Mozi" to "Nine Chapters No. 2", Pan Jianwei, an academician of the Chinese Academy of Sciences, has in mind the exploration of the quantum world and the pursuit of the development of quantum science and technology in China.
Pan Jianwei told the "Lookout" news weekly that quantum science and technology is related to the national strategy, with the "great power of the country", only by constantly breaking through innovation, we must strive to explore a more flexible and efficient, resource integration of collaborative innovation road, so that China's quantum technology development has always been at the forefront of the world.
"Chinese can do a good job in scientific research"
"Lookout": Why did you name the world's first quantum science experimental satellite "Mozi"?
Pan Jianwei: It feels very easy to watch the launch video now, but in fact, 30 seconds before the launch, I kept my hands together, hoping that the satellite could successfully enter space. The name of this satellite "Mozi" is because Mozi is the "Kesheng" in Chinese history, and I want to tell you that Chinese can do a good job in scientific research.
Mozi lived 2400 years ago, and he advocated both love and non-aggression, that is, equal fraternity and opposition to war. He proposed in the "Ink Classic" that "stop, to be long, not to last", said that the reason why an object will stop is mainly because of the action of force, if there is no resistance, the movement of an object will never stop, which is actually the same concept as Newton's first law of motion. In addition, Mozi did small hole imaging experiments more than 2,000 years ago. We know that light only does this happen if it travels in a straight line.
We named the world's first quantum science experimental satellite "Mozi", on the one hand, to commemorate Mozi's achievements in optical research, but also to highlight our cultural self-confidence.
"Lookout": What role did the "Mozi" play?
Pan Jianwei: The use of quantum satellites to establish a quantum communication network can cover all kinds of islands, ocean-going ships, overseas institutions and other places where optical fibers are difficult or unreachable on a global scale, ensuring China's information transmission security on a global scale. The experiment of "Mozi" fully verified this feasibility.
"Mozi" has successfully completed three major scientific experimental tasks. On this basis, the docking of "Mozi" and "Beijing-Shanghai Trunk Line" was completed, and intercontinental quantum confidential communication was realized. In addition, "Mozi" also provides a new platform for testing basic problems in physics such as the fusion of quantum mechanics and gravity.
Quantum computing research is located in the international first square
Lookout: What is the significance of the "nine chapters" of successfully building a quantum computing prototype?
Pan Jianwei: According to the best classical algorithm at that time, the calculation speed of the Gaussian Bose sampling problem in the "Nine Chapters" was one hundred billion times faster than that of the world's fastest supercomputer "Fuyue", thus achieving the "superiority of quantum computing" in the second place in the world. The name "Nine Chapters" commemorates the famous ancient Chinese mathematical treatise "Nine Chapters of Arithmetic".
To achieve this breakthrough in 2020, we have actually experienced 20 years of hard work. The breakthrough of the "Nine Chapters" mainly overcomes three major technical difficulties: high-quality quantum light source, high-precision phase-locked technology, and large-scale interference technology.
Since the beginning of this year, our team has carried out a series of concept and technological innovations, and recently successfully developed the "Nine Chapters AND 2". We mainly have three major breakthroughs, the first of which significantly improves the yield, quality and collection efficiency of quantum light sources, and increases the key indicators of light sources from 63% to 92%. Second, increase the number of multiphoton quantum interference lines from 100 dimensions to 144 dimensions, and the number of photons manipulated increases from 76 to 113. Third, programmable features have been added.
The results show that the computing power of "Nine Chapters and Two" has been greatly improved. According to the best classical algorithm published so far, the processing speed of the "Nine Chapters II" to solve the Gaussian Bosian sampling problem is 100 billion billion times faster than the world's fastest supercomputer, and 10 billion times faster than the "Nine Chapters" of 76 photons. The current "Nine Chapter Two" is still only a "single champion", which can only solve the specific problem of Gaussian Bose sampling, but the solution to this problem has potential application value in the fields of graph theory and quantum chemistry.
"Lookout": Quantum computing includes a number of technical routes, what is the layout of China's superconducting quantum computing?
Pan Jianwei: In addition to optical quantum computing, we also have a good layout in the direction of superconducting quantum computing.
In May this year, we built the 62-bit superconducting quantum computing prototype "Zu Chong Zhi", which had the largest number of superconducting qubits at that time, and realized programmable two-dimensional quantum walking. On the basis of "Zuchong No.", we adopt a new flip-back soldering 3D packaging process to solve the problem of large-scale bit integration, and successfully develop "Zuchong No. 2", realizing the high-density integration of 66 data bits, 110 coupling bits, and 11 readings. Through quantum programming, we realized the sampling of quantum random circuits, demonstrating the programming ability of Zuchong-2 to execute arbitrary quantum algorithms. According to the optimized classical algorithm that has been published so far, the processing speed of the quantum random line sampling problem by "Zu Chong Zhi No. 2" is more than 10 million times faster than that of the fastest supercomputer at present, and about 40,000 times faster than Google's prototype "Plane Tree".
Endeavor Quantum Information Strategy Technology
Lookout: What will the development of quantum information technology bring us?
Pan Jianwei: Quantum information technology is not only a strategic technology in China, but also an important strategic layout for major developed countries in Europe and the United States. Just as transistors are the foundation of computers, laser technology is an important support for the modern Internet, and the development of navigation technology is inseparable from the support of precision measurement technologies such as atomic clocks... The establishment of quantum mechanics directly gave birth to the development of modern information technology. After more than 100 years of development, quantum mechanics has made technical reserves to solve some of the problems we are currently encountering.
Quantum communication provides a principled unconditional and secure way of communication, which can greatly improve the security of existing information systems.
The computational power of quantum computing grows exponentially as the number of qubits increases. The ability of quantum computing to perform parallel operations can be used for large number decomposition, solving systems of linear equations, etc. For example, it takes 150,000 years to decompose a large number of 300 bits using a trillion-time classical computer, but it only takes 1 second to use a trillion-time quantum computer. Therefore, quantum computing shows a strong potential and can be used for classical code breaking, weather forecasting, financial analysis, drug design, revealing new energy and new material mechanisms and other applications.
Lookout: What's your next goal?
Pan Jianwei: In the field of quantum computing, the international academic community has defined 3 phased goals, and the first phase of the goal has been achieved. The second stage is to complete the realization of the principle of quantum error correction, develop a dedicated quantum simulation machine that coherently manipulates hundreds of qubits, and apply it to specific problems such as combination optimization, quantum chemistry, and machine learning, and guide material design and drug development. It takes 5 to 10 years to reach this stage and is currently the main research task.
In the field of quantum communication, we hope that through 10 to 15 years of efforts, we will develop a complete relevant technology of space-earth integrated wide-area quantum communication, and promote the wide application of quantum communication in finance, government affairs, energy and other fields. At the same time, the high-precision optical quantum transmission technology and space quantum science experimental platform developed by wide-area quantum communication are used to build a high-precision time-frequency transmission network, which makes an important contribution to the definition of the next generation of "seconds". On this basis, we hope to be able to carry out research on basic physics problems such as gravitational wave detection and dark matter search.