Scientists have discovered a new way to control quantum light sources by twisting atomically thin layers of a material known as hexagonal boron nitride (hBN), a breakthrough that could help bring quantum technologies closer to practical use.

Researchers from the University of Technology Sydney found that rotating and restacking layers of hBN can significantly alter the color and wavelength of light emitted by quantum emitters embedded within the material.

Quantum emitters are tiny light sources that can produce single photons, making them important building blocks for future quantum computers, secure communication networks, and highly sensitive sensors. While scientists have been able to detect and study these emitters, controlling them has remained a major challenge.

The team says its approach offers a new way to tune these light sources by exploiting the unique layered structure of hBN, a material that can be repeatedly separated, twisted, and reassembled.

Twisting light into control

Lead author Dr. Angus Gale said the findings provide researchers with a new tool for manipulating quantum emitters.

“You can measure these quantum emitters and see that they exist, but it’s hard to make them work in practice. This gives us a lever to get closer to that – a step towards the realisation of quantum technologies,” said Dr Gale.

In experiments, the researchers were able to produce a significant shift in the emitted light by changing the twist angle between layers. Unlike many studies where materials are assembled once and left unchanged, the team repeatedly picked up, twisted, and restacked the layers while continuing to modify the optical properties.

“We’re leveraging the fact that this material, hexagonal boron nitride (hBN), is layered. We can pick it up, stack it, twist it, and use that twist to modify the emitters. You can’t really do that with traditional materials like diamond or silicon carbide.”

According to the researchers, the amount of tuning achieved was larger than expected and exceeded what is typically possible in many other quantum emitter platforms.

“The benefit is that we used this twistable platform to shift the emission by a very significant amount,” said Gale. “Often when you control these systems, the amount of manipulation is very limited, but in this case the shift was much larger than expected.”

New path for quantum

Rather than forcing hBN to behave like more conventional quantum materials, the team focused on taking advantage of its natural properties.

“Rather than trying to make hBN defects behave like a traditional solid-state hosts, we took advantage of hBN’s own strength: its thin, layered, twistable structure.”

Gale compared the material to slices of cheese rather than a solid block.

“With a block of cheese, you can’t really get to the flavour in the middle. But with slices, you can peel away layers, put them back together and change how they interact,” he said.

Professor Igor Aharonovich said twisting layered materials can produce entirely new physical behaviors.

“You can take two layers that don’t do much on their own, put them together at a specific angle, and suddenly you have a completely different system,” said Professor Aharonovich.

The researchers believe the approach could eventually contribute to the development of quantum computing, quantum communication, and quantum sensing technologies used in fields ranging from healthcare to cybersecurity and navigation.

The study was published in Advanced Materials.

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