produces for the first time the ultrapure silicon that its competitors controlled

China is a powerhouse in quantum technologies. In fact, in this area he looks directly at the US. These two countries have accumulated notable milestones over the past few years, including the quantum supremacybut his leadership diverges depending on the area. In quantum computing The US accumulates 34% of the most cited articles compared to 16% Chinesewhile in quantum telecommunications China leads with 34% of reference scientific production vs. 17% United States.

The patent landscape reflects that same duality. China monopolizes around 60% of all requests global quantum technology patents registered in 2024, but when the filter is applied to international patents (those protected simultaneously in several countries), The US leads with 48% compared to 11% Chinese. Although, as we have just seen, China is making important achievements in the field of quantum technologies, it is to some extent dependent on some innovations from abroad.

In the current situation of tension with the United States and its allies, this gigantic Asian country needs to become independent from foreign quantum technologies, and has just taken a very important step forward in this direction. The Chinese State Nuclear Corporation has announced that one of its research institutes has for the first time produced high-purity silicon-28 with an isotopic abundance greater than 99.99%. This isotope is decisive because it is considered the raw material for quantum hardware with the greatest scale potential: quantum computers based on silicon.

Silence is everything

The reason why silicon-28 matters so much must be found in physics. Natural silicon is composed mostly of silicon-28, but contains approximately 4.7% silicon-29, an isotope with non-zero nuclear spin. This detail is innocuous for a classical transistor, but is devastating for a quantum computer because the silicon-29 cores act as sources of magnetic noise that disturb the qubits, causing them to lose their quantum state in fractions of a second.

Enriching the silicon until that impurity is almost completely eliminated is equivalent to building an anechoic room for the qubits: an environment where noise disappears and quantum information can persist long enough to operate on. A silicon-based quantum computer uses electron spin trapped in quantum dots (nanostructures manufactured on a silicon wafer) as a basic unit of information. Coherence, that is, the ability of the qubit to maintain its quantum state long enough to operate on it, depends directly on how quiet the surrounding environment is.

In natural silicon, the magnetic field generated by the silicon-29 nuclei drastically limits this coherence. However, in silicon-28 enriched to 99.99% that field disappears. The most recent experiments on wafers manufactured with standard industrial CMOS processes have yielded coherence times of up to 803 microseconds and relaxation times of 6.3 seconds, as well as operating fidelities exceeding 99% in both one- and two-qubit gates. These numbers make sense when put against those of other qubit technologies.

Superconducting qubits, the bet of Google and IBM, are extraordinarily fast in the execution of logic gates, but require cooling at temperatures close to absolute zero (around 15 millikelvin) and their coherence times They are measured in tens of microseconds. Trapped ion qubits, for their part, achieve coherences of several seconds and very low error rates, but their operations are slow and scaling them beyond a hundred qubits is extraordinarily difficult. In fact, they require ultra-fine vacuum systems, complex electromagnetic traps and surgically precise lasers.

Spin qubits on silicon-28 are not the fastest or most coherent in absolute terms, but they combine sufficiently long coherence with an advantage that no other platform can match. That advantage is compatibility with the semiconductor industry as it exists today. Spin qubits in silicon are manufactured on 300 mm wafers using standard CMOS processes, the same ones that TSMC, Intel or Samsung use to produce classic transistors. This means that, in principle, the transition from a handful of qubits to millions integrated on a single chip is not limited by unknown physics, but by the same manufacturing engineering that the industry has mastered for decades.

For China, which has invested many resources in building and strengthening its own semiconductor industry, being able to autonomously produce the base material on which this architecture depends is not only a scientific milestone; It’s a strategic move that connects its quantum agenda with its chip industry. And, as a tip, also with its broader objective of technological autonomy compared to the West.

Image | Maxence Pira (Unsplash)

More information | SCMP

In Xataka | 38% of AI experts in the US have been trained in China. They are essential to sustain your leadership