Year-end review: Major breakthroughs in Chinese science and technology in 2021

2021 is coming to an end. The past year has been a year of record-breaking achievements and great harvests in the science and technology community. This year coincides with the 100th anniversary of the founding of the Communist Party of China, and my country's science and technology community has made many important breakthroughs. Quantum computing has made significant progress, making my country the only country to achieve quantum computing superiority in two physical systems; the "China Sky Eye" has officially opened to the world, showing the demeanor of a great power; the successful realization of artificial synthesis of starch from carbon dioxide has provided new possibilities for the future of mankind...

This year, the scientific and technological workers have been working tirelessly. They have been indomitable in their pursuit of scientific truth and have continuously set new heights that humans can reach. The scientific and technological community will surely set sail again with the east wind of the times and march forward towards a more colorful future.

1

Recovering the "ancestral" genes of rice

Helps to cultivate better rice varieties

Rapidly domesticate allotetraploid wild rice from scratch, give full play to the advantages of polyploidy, recover some of the excellent genes that have been lost in current cultivated rice, and cultivate new rice crops with higher yields and stronger environmental adaptability - this breakthrough progress made by Li Jiayang's team and collaborators from the Seed Innovation Institute and the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences was published in the internationally renowned academic journal Cell on February 4.

Polyploidization is an important mechanism of plant evolution. The cultivated rice we grow today has undergone thousands of years of artificial domestication, and its agronomic traits have been continuously improved, but at the same time it has also lost a lot of genetic diversity, resulting in the loss of advantageous gene resources. Allotetraploids have two more chromosome sets than diploids. Allotetraploid wild rice has the advantages of large biomass, self-contained hybrids, and strong environmental adaptability. However, its non-domesticated characteristics also make it impossible to directly apply it to agricultural production.

Starting from tetraploid wild rice with better overall performance, Li Jiayang's team used modern genome editing technology to "replay" the history of rice domestication that lasted for thousands to tens of thousands of years in a short period of time, and avoided the loss of some genes. For the first time, they designed and completed the framework diagram for the rapid de novo domestication of allotetraploid wild rice, which is expected to cultivate new rice crops with high yield and strong environmental adaptability. The research team broke through technical bottlenecks such as genome analysis, efficient genetic transformation, and efficient genome editing, annotated a series of domestication genes and important agronomic trait genes in the genome of allotetraploid tall wild rice, and successfully created a variety of genome-edited allotetraploid wild rice materials with reduced grain shattering, shorter awn length, lower plant height, longer grain length, thicker stems, and shorter heading time to varying degrees.

2

New edition of "Nine Chapters" and "Zu Chongzhi"

Achieving quantum supremacy in two physical systems

Developing quantum computers with practical value has always been one of the most important development goals in the field of quantum computing, and is also the focus of competition among countries. In the past year, my country has made a number of major advances in the field of quantum computer research and development.

On February 27, the international authoritative journal Science Advances published a result. A new type of programmable silicon-based optical quantum computing chip developed by researchers from the National University of Defense Technology, the Academy of Military Sciences, Sun Yat-sen University and other institutions has realized quantum algorithm solutions to a variety of graph theory problems and is expected to be applied in fields such as big data processing in the future.

On May 7, Science magazine published the research results of Pan Jianwei's team at the University of Science and Technology of China. They successfully developed a quantum computing prototype "Zu Chongzhi", which manipulated 62 superconducting quantum bits and realized programmable two-dimensional quantum walks on this basis. This achievement has laid a technical foundation for achieving quantum supremacy in superconducting quantum systems and subsequent research on quantum computing with great practical value.

At the end of October, Pan Jianwei's team further developed a 66-bit programmable superconducting quantum computing prototype "Zu Chongzhi 2.0", which achieved quantum computing superiority in random circuit sampling tasks. The difficulty of the completed task was 2-3 orders of magnitude higher than Google's "Platanus" in 2019.

At the same time, the upgraded version of "Jiuzhang 2.0" by Pan Jianwei's team has also greatly improved its quantum advantage. For the Gaussian boson sampling problem, the task that "Jiuzhang" could complete in one minute a year ago would take the world's most powerful supercomputer 100 million years; while the task that "Jiuzhang 2.0" can complete in one minute would take the supercomputer 10 billion times longer. And "Jiuzhang 2.0" also has partial programmability.

The emergence of "Jiuzhang 2.0" and "Zu Chongzhi 2.0" makes my country the only country to achieve quantum computing superiority in two physical systems.

3

"China's Sky Eye" welcomes scientists from around the world

Observation applications will be collected starting at the end of March

In line with the principle of open sky, the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), a major national scientific and technological infrastructure known as the "China Sky Eye", has invited astronomers from all over the world to apply for observations since 0:00 Beijing time on March 31, 2021. All foreign applications will be reviewed uniformly. The observation time will start in August this year.

The "China Sky Eye" will solicit observation applications from astronomers around the world starting March 31. Photo by Xinhua News Agency reporter Ou Dongqu

The China Sky Eye is located in Dawotang, Pingtang County, Qiannan Prefecture, Guizhou Province. It was completed in 2016 and is the world's largest single-aperture and most sensitive radio telescope with independent intellectual property rights. Like optical telescopes, the larger the aperture of a radio telescope, the more electromagnetic waves it receives, the higher its sensitivity and the stronger its detection capability. In this way, the China Sky Eye can monitor weak radio signals in the universe.

Since the national acceptance and start of operation, the China Sky Eye facility has been running stably and reliably, and the number of pulsars discovered has reached more than 500, and major breakthroughs have been made in research fields such as fast radio bursts. The development and construction of the China Sky Eye not only reflects my country's independent innovation capabilities, but also promotes the development of many high-tech fields such as antenna manufacturing technology, microwave electronics technology, parallel robots, large-scale structural engineering, and kilometer-range high-precision dynamic measurement.

Wu Xiangping, academician of the Chinese Academy of Sciences and director of the FAST Scientific Committee, said that FAST is open to global use, demonstrating the concept of full cooperation and the practice of the concept of a community with a shared future for mankind.

4

Using liquid helium to create a world at -271℃

Large-scale cryogenic refrigeration equipment "made in China"

On April 15, the national major scientific research equipment development project "Development of large-scale cryogenic refrigeration system in the temperature range of liquid helium to superfluid helium" undertaken by the Institute of Physics and Chemistry of the Chinese Academy of Sciences (hereinafter referred to as the Institute of Physics and Chemistry of the Chinese Academy of Sciences) passed the acceptance and results appraisal. The project results appraisal expert group believes that the overall technology of the project has reached the international advanced level. This indicates that my country has the ability to develop large-scale cryogenic refrigeration equipment of kilowatt level at liquid helium temperature (-269℃) and hundred-watt level at superfluid helium temperature (-271℃).

Large-scale low-temperature refrigeration system in the domestically produced liquid helium temperature zone. Image source: Institute of Physics and Chemistry, Chinese Academy of Sciences

Liquid helium is a "magic weapon" for creating ultra-low temperatures. With the rapid development of social economy, my country has become a major user of large-scale cryogenic refrigeration equipment. However, due to the lack of large-scale cryogenic refrigeration systems, key sub-equipment and integrated technology, my country's large-scale cryogenic refrigeration equipment has long been monopolized by foreign countries and has a high degree of import dependence.

In December 2015, the Institute of Physics and Chemistry of the Chinese Academy of Sciences started the research and development of large-scale low-temperature refrigeration equipment in the temperature range from liquid helium to superfluid helium. Based on decades of accumulation of cryogenic technology, after five years of hard work and adherence to the path of independent innovation, it finally successfully developed a large-scale helium refrigerator with advanced technical indicators.

5

Optical storage time up to 1 hour

An important step towards quantum USB drives

In April, the research groups of Li Chuanfeng and Zhou Zongquan from the team led by Guo Guangcan of the University of Science and Technology of China increased the optical storage time to 1 hour, significantly breaking the world record of 1 minute of optical storage created by a German team in 2013, and taking an important step towards the realization of quantum USB flash drives. The achievement was published in the authoritative academic journal Nature Communications in late April.

Data map. Image source: pixabay

Light has become the basic carrier of modern information transmission. The speed of light is as high as 300,000 kilometers per second. "Slowing down" the speed of light or even making light "stop" has been the goal that the international academic community has been working hard for. The storage of light is particularly important in the field of quantum communication. By storing photons in ultra-long-life quantum memory, that is, quantum USB flash drives, quantum information can be transmitted by directly transporting quantum USB flash drives. Considering the speed of transportation such as airplanes and high-speed trains, the optical storage time of quantum USB flash drives must be at least hours.

In 2015, the research group of Li Chuanfeng and Zhou Zongqun made their own optical Raman heterodyne detection nuclear magnetic resonance spectrometer. Relying on this instrument, they accurately characterized the complete Hamiltonian of optical transitions in europium-doped yttrium silicate crystals, and theoretically predicted the energy level structure under the magnetic field where the first-order Zeeman effect is zero (ZEFOZ).

In the future, relying on more mature quantum USB flash drives, humans are expected to realize quantum information transmission based on classical transportation tools, thereby establishing a new quantum channel.

6

Artificial sun breaks world record

Achieve repeatable combustion at 120 million degrees Celsius for 101 seconds

On May 28, good news came from the Hefei Institutes of Physical Science, Chinese Academy of Sciences. The fully superconducting tokamak nuclear fusion experimental device (EAST), known as the "artificial sun", made a new breakthrough and successfully achieved repeatable plasma operation at 120 million degrees Celsius for 101 seconds and 160 million degrees Celsius for 20 seconds, setting a new world record for the operation of the tokamak experimental device and taking an important step towards the application of nuclear fusion energy.

The "artificial sun" achieved repeatable plasma operation at 120 million degrees Celsius for 101 seconds and 160 million degrees Celsius for 20 seconds. Photo by Xinhua News Agency reporter Zhou Mu

The light and heat that all things on Earth rely on for growth all come from the energy released by the nuclear fusion reaction in the sun. The fuel that supports this fusion reaction, deuterium, is extremely abundant on Earth, enough for humans to use for tens of billions of years. If deuterium can be used to create an "artificial sun" to generate electricity, humans will hopefully achieve complete energy freedom.

However, the manufacture of an "artificial sun" faces an outstanding practical problem: what container can be used to carry nuclear fusion? The ion temperature of the plasma under artificial control conditions must reach more than 100 million degrees Celsius. The melting temperature of tungsten, the most high-temperature resistant metal material on earth, is more than 3,000 degrees Celsius. This means that it is necessary to build a device that can simultaneously carry complex environments such as large currents, strong magnetic fields, ultra-high temperatures, ultra-low temperatures, high vacuums, and high insulation, which places extremely high demands on process design and materials.

In order to meet the conditions required by the fusion experimental device, the scientists of the EAST team independently innovated, independently designed and developed most of the key technologies with independent intellectual property rights, and creatively completed the overall engineering design of the mainframe of the EAST device. The world's new generation of all-superconducting tokamak nuclear fusion experimental device was first built and officially put into operation in China, providing an experimental research platform for the future utilization and development of clean energy.

7

Earth Simulator Launched

See the Earth's past, present and future clearly

On June 23, the Earth System Numerical Simulation Facility, a major national scientific infrastructure, was completed and put into use in Beijing Huairou Science City. This is the first large-scale scientific facility for earth system simulation successfully developed in my country with independent intellectual property rights.

The Earth System Simulator, also known as the Earth Simulation Laboratory, is a facility that performs numerical simulations of the Earth system. That is, it uses Earth system observation data as a basis and uses the laws that describe the physical, chemical and life processes of the Earth system and their evolution to perform large-scale scientific calculations on supercomputers. This allows scientists to recreate the Earth's past, simulate the Earth's present, and predict the Earth's future.

The overall performance of the newly completed and put into use Earth Simulation Laboratory is comparable to the international advanced level. It is my country's first dedicated Earth system numerical simulation device with independent intellectual property rights, with numerical simulation software for various spheres of the Earth system as the core, and software and hardware collaborative design. Its scale and comprehensive technical level are at the forefront of the world. It has the ability to simulate various spheres of the Earth's surface and can consider various processes of the Earth system more comprehensively. Especially in the most urgent field of climate change response and carbon neutrality, the system can pay full attention to global ecological and biogeochemical processes and their interactions with the climate system, and on this basis, establish a clear relationship of "ecology-temperature-carbon dioxide concentration-carbon emissions", provide strong simulation support for greenhouse gas accounting and future warming forecasts, and help achieve the vision of carbon peak and carbon neutrality. It will also provide a basis for my country's future negotiations in the field of climate and environment, and enhance my country's international voice.

8

The advent of "ice fiber"

Flexible bending and efficient light guidance

On July 9, the authoritative academic journal Science published a result showing that the team of Professor Tong Limin from the School of Optoelectronic Science and Engineering of Zhejiang University, together with researchers from the Center for Interdisciplinary Mechanics of Zhejiang University and the University of California, Berkeley, prepared high-quality ice single crystal micro-nano optical fiber in a -50°C environment. It can bend flexibly and transmit light with low loss, and its performance is similar to that of glass optical fiber.

As a functional structure that can confine and freely transmit light, optical fiber is currently one of the most effective tools for light field manipulation. The main component of conventional glass optical fiber is silicon oxide (quartz sand), which is one of the most abundant substances in the earth's crust. But in fact, on Earth and many extraterrestrial bodies, the substance that is more common than quartz sand is ice or liquid water. Therefore, using ice to prepare optical fiber has a wide range of application prospects.

In this study, Tong Limin's team built a growth device on their own. Based on a large number of experiments, they improved the existing electric field-induced ice crystal preparation method. In a low-temperature, high-voltage electric field, supplemented by certain humidity conditions, static electricity was used to induce water molecules to move in the direction of the electric field, changing their disordered motion state, thereby inducing single crystal growth. Finally, in an environment of -50°C, ice single crystal micro-nano optical fibers with diameters ranging from 800 nanometers to 10 microns were successfully prepared. In addition, the team also used the newly invented low-temperature micro-nano manipulation and transfer technology to enable the ice micro-nano optical fiber to obtain an elastic strain of 10.9% in an environment of -150°C, close to the theoretical elastic limit of ice.

Tong Limin believes that the results of this study will expand people's understanding of ice, inspire people to conduct research on ice-based optical fibers in optical transmission, optical sensing, ice physics, and develop micro-nanoscale ice-based technologies suitable for special environments.

9

"Get rid of" photosynthesis to synthesize starch

Save resources while improving production efficiency

On September 23, the Chinese Academy of Sciences announced a major achievement. Researchers from the Tianjin Institute of Industrial Biotechnology of the Academy proposed a disruptive starch preparation method that does not rely on plant photosynthesis. It uses carbon dioxide and hydrogen produced by electrolysis as raw materials to successfully produce starch. This is the first time in the world that de novo synthesis of carbon dioxide to starch has been achieved, making it possible to transform starch production from traditional agricultural planting mode to industrial workshop production mode. The relevant research results were published online in the journal Science on September 24.

Chinese scientists have achieved the first complete synthesis of starch molecules from carbon dioxide in the laboratory. Photo by Xinhua News Agency reporter Jin Liwang

Starch is mainly synthesized by green plants through photosynthesis to fix carbon dioxide. In crops such as corn, the conversion of carbon dioxide into starch involves more than 60 metabolic reactions and complex physiological regulation, and the theoretical utilization efficiency of solar energy does not exceed 2%. The cultivation of crops requires a cycle of several months and uses a large amount of land, fresh water, fertilizer and other resources.

To improve production efficiency, researchers at the Tianjin Institute of Industrial Biology, Chinese Academy of Sciences, designed a new pathway for unnatural carbon dioxide fixation and artificial starch synthesis with 11 main reactions from scratch, achieving the first full synthesis from carbon dioxide to starch molecules in the laboratory. The starch synthesis rate of this artificial pathway is 8.5 times that of corn starch. And under the condition of sufficient energy supply, according to current technical parameters, theoretically, the annual starch production of a 1 cubic meter bioreactor is equivalent to the average annual production of corn on 5 mu of land in my country.

10

Proving the Kähler geometry core conjecture

Solving a 60-year-old mystery in mathematics

In early November, Professor Xiuxiong Chen, founding director of the Center for Geometric Physics at the University of Science and Technology of China, and his collaborator Jingrui Cheng achieved milestone results in the field of partial differential equations and complex geometry. They solved a fourth-order fully nonlinear elliptic equation, successfully proved the coercive conjecture and the geodesic stability conjecture, two core conjectures that have been pending in the international mathematics community for more than 60 years, and solved several famous problems related to the constant scalar curvature metric and the Calabi extremum metric on Kähler manifolds. The two papers were published in the internationally renowned journal Journal of the American Mathematical Society.

Professor Chen Xiuxiong (center), founding director of the Center for Geometric Physics, and Cheng Jingrui (left). Photo by Tao Dongqing, Anhui News

The existence of a constant scalar curvature metric on a Kähler manifold has been one of the core problems in geometry for the past 60 years. There are three famous conjectures about its existence - the stability conjecture, the coercion conjecture, and the geodesic stability conjecture. After nearly 20 years of work by many famous mathematicians, the necessity of the coercion conjecture and the geodesic stability conjecture has become completely clear, but the proof of their sufficiency was previously considered out of reach.

By solving a class of fourth-order fully nonlinear elliptic equations, we can prove the existence of a constant scalar curvature metric. The work of Chen Xiuxiong and Cheng Jingrui is precisely to prove the existence of solutions to this type of equations under the assumption of K-energy coercion or geodesic stability. They not only found the solution to the equation, but also established a set of systematic methods to study this type of equations, providing a new tool for exploring the unknown mathematical world. In addition, they also gave a proof of the stability conjecture on ring-symmetric Kähler manifolds, generalized Donaldson's classic theorem on ring-symmetric Kähler surfaces to high dimensions, and proposed a possible solution to the proof of the general stability conjecture, making it possible to completely solve the general stability conjecture.

Source: Science and Technology Daily

◎ Science and Technology Daily intern reporter Du Peng

Editor: Zhang Qiqi

Review: Julie

Final review: Liu Haiying