Will quantum chips now be easily manufactured?

Researchers at Peking University have produced rhombohedral graphene, a material capable of exhibiting unusual properties such as the quantum anomalous Hall effect and strong electron interactions, with a phase purity exceeding 99 per cent. Although the new method has not yet produced a working quantum chip, it removes a major barrier to moving graphene-based quantum devices from laboratory experiments towards reproducible production.

Graphite is a fundamental industrial material used in applications ranging from pencils and steelmaking to lubricants and battery electrodes. Graphene, its atomically thin building block, has long been regarded as one of the most promising materials for future electronics because of its high electrical conductivity, mechanical strength and unusual electronic properties.

A new study led by researchers at Peking University in China has now made the less common rhombohedral form of graphene more accessible for quantum technology applications by enabling its controlled production.

The findings were published in Science on 23 July 2026 under the title “Step geometry–guided growth of rhombohedral graphene.” The research team, led by Kaihui Liu, developed an epitaxial production method that uses the step geometry of the growth surface to control how graphene layers are stacked.

Layer arrangement determines graphene’s properties

The physical properties of multilayer graphene depend not only on the number of layers but also on how its carbon sheets are positioned relative to one another.

In the more common Bernal stacking structure, the layers follow an ABA arrangement. In rhombohedral graphene, however, they are stacked in an ABC sequence. Although this difference may appear small at the atomic scale, it significantly changes the material’s electronic band structure and the interactions between its electrons.

Rhombohedral graphene provides an important material platform for investigating flat electronic bands, high electron density, superconductivity, magnetic states and topological quantum phases. However, the structure is thermodynamically metastable and can easily transform into more stable graphene arrangements during production.

This instability has made it difficult to produce sufficiently large, high-purity rhombohedral graphene samples. Until now, researchers have mainly relied on small flakes obtained by mechanically exfoliating graphite, a process that offers limited control over sample size and layer structure.

Phase purity exceeds 99 per cent

The Peking University team developed what it describes as a step geometry–guided epitaxial growth strategy. The method enables researchers to control the relative sliding of graphene layers and preserve the desired ABC stacking arrangement during growth.

According to the Science paper, the researchers:

• Produced rhombohedral graphene with a phase purity above 99 per cent.
• Increased the sample area to as much as 160 by 80 micrometres.
• Created structures ranging from approximately 15 layers to 120 nanometres in thickness.
• Established Raman spectroscopy and intrinsic electronic band-structure references covering samples from a few layers to approximately 200 layers.

The dimensions achieved remain far below the wafer scale used in modern semiconductor manufacturing. Nevertheless, the study is significant because it turns rhombohedral graphene production, previously dependent mainly on chance discoveries during mechanical exfoliation, into a controlled growth process.

Quantum anomalous Hall effect observed

The researchers examined not only the material’s structure but also its electronic transport characteristics. Measurements revealed a layer-antiferromagnetic state and the quantum anomalous Hall effect.

The quantum anomalous Hall effect is a topological quantum phenomenon that can allow low-loss electrical currents to flow along the edges of a material without requiring an external magnetic field. It is being investigated for low-energy electronic circuits, topological quantum devices and potentially more fault-tolerant quantum computing architectures.

However, it would be premature to describe the new study as the production of a graphene quantum chip. Rather than presenting a functioning and scalable quantum processor, the research demonstrates a reproducible method for producing a high-quality quantum material that could eventually be used in such devices.

Further steps needed for industrial production

For the method to become an industrial manufacturing process, rhombohedral graphene will need to be grown over much larger areas while preserving uniform thickness and stacking order across an entire wafer. The process must also be made compatible with existing semiconductor manufacturing technologies.

Other engineering challenges include transferring the material to different substrates without introducing defects, forming reliable electrical contacts, patterning it at the nanoscale and reproducing the same electronic performance in high-volume production.

Despite these limitations, the study demonstrates that the production method can be just as important as the material itself in quantum technology. Controlling how atomic layers slide during growth could allow graphene’s electronic behaviour to be designed directly through the manufacturing process.

The Peking University team’s findings therefore represent an important step towards transforming rhombohedral graphene from a rare material examined in small laboratory samples into a manufacturable platform for next-generation quantum electronics.

Sources: Science, South China Morning Post.