Breakthrough shows Chinese engineers closed a critical gap in industrial chain

Chinese scientists have achieved a key technological breakthrough that is expected to advance the country's efforts in quantum computing and semiconductor development.

The Research Institute of Physical and Chemical Engineering of Nuclear Industry, a Tianjin-based subsidiary of China National Nuclear Corp, announced on Monday that it had mass-produced silicon-28 isotope with extremely high purity.

The product features an isotopic abundance exceeding 99.99 percent, ending China's reliance on imports for the material.

READ MORE: China achieves breakthrough in key material for silicon-based quantum chips

Han Liguo, a senior researcher leading the project, said natural silicon contains three isotopes — silicon-28, silicon-29 and silicon-30 — with silicon-28 accounting for 92.2 percent.

Characterized by zero nuclear spin, silicon-28 can significantly reduce environmental noise interference in quantum computing, earning it the title of "the purest silicon on Earth".

"By contrast, silicon-29, another stable isotope found in natural silicon, creates disturbances in quantum computing operations," Han said. "To minimize such interference, the isotopic abundance of silicon-28 must be raised above 99.99 percent."

According to the institute, only a handful of countries have mastered large-scale production of stable isotopes. As a result, China depended on imports for high-end stable isotope products, a situation that has constrained the development of related industries, affected security in key sectors and hindered independent progress in advanced equipment manufacturing, nuclear medical diagnostics and frontier scientific research.

Founded in 1964, the institute is China's leading research body specializing in isotope separation technology. In recent years, it has leveraged its expertise in nuclear technology to develop equipment and processes for the mass production of stable isotopes.

The institute said it has established a fully independent research and production system, ensuring a domestic supply of stable isotopes.

Han said high-purity silicon-28 is an ideal material for manufacturing silicon-based qubits. It significantly improves qubit coherence and control precision, providing critical material support for the research and development of silicon-based quantum computers.

The isotope can also be used in high-end semiconductors, she said, adding that semiconductor components made from silicon-28 offer improved thermal conductivity and performance stability, creating broad opportunities for use in advanced chip manufacturing.

Lei Zengguang, an academician of the Chinese Academy of Engineering and an expert in nuclear materials and nuclear fuels, said stable isotope technology is a key component of the nuclear industry.

"It may appear to be a niche field, but it is an essential enabling technology for many critical sectors, including precision manufacturing, quantum technology, biomedicine, environmental monitoring and nuclear energy," Lei said.

"Gaining full independent control of core stable isotope separation technology has long been a shared goal for those of us working in the industry. In recent years, the Research Institute of Physical and Chemical Engineering of Nuclear Industry has achieved major breakthroughs, successfully isolating more than 20 important stable isotopes."

The new capability to mass-produce silicon-28 with an isotopic abundance above 99.99 percent means Chinese engineers have not only mastered the relevant technologies but have also closed a critical gap in the industrial chain, Lei said.

He said the achievement carries major implications for China's quantum technology and high-end chip industries.

Beyond those sectors, high-purity silicon-28 also has significant potential for applications in advanced medical treatment and space exploration, he added.

Contact the writers at zhaolei@chinadaily.com.cn