Researchers at the University of Technology Sydney have demonstrated a new way to control tiny sources of quantum light by twisting atomically thin layers of hexagonal boron nitride.
The advance provides scientists with a new method for tuning quantum emitters, which are microscopic light sources that could play an important role in future technologies such as quantum computing, secure communications, and ultra-sensitive sensors.
Lead author Dr. Angus Gale said the work offers researchers a valuable new tool for making these quantum systems more practical.
“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 realization of quantum technologies,” said Dr. Gale.
Twisting Layers Changes Quantum Light
During the experiments, Gale and his team found that twisting the material could significantly alter both the color and wavelength of the light emitted by the quantum emitters. The magnitude of the change was especially noteworthy.
Most studies create a device at a specific twist angle and leave it unchanged. In contrast, the researchers were able to repeatedly lift, rotate, and restack the material, allowing them to continuously modify its 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.”
“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.
“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.”
Why Hexagonal Boron Nitride Is Different
Gale compared the material’s structure to slices of cheese rather than a solid block.
“With a block of cheese, you can’t really get to the flavor in the middle. But with slices, you can peel away layers, put them back together and change how they interact,” he said.
Because hBN is made of extremely thin layers, researchers can separate and reassemble those layers in ways that are not possible with more conventional quantum materials.
New Possibilities for Quantum Technologies
Supervising author Professor Igor Aharonovich said the ability to twist layered materials is particularly exciting because it can reveal entirely new physical behavior.
“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.
According to Aharonovich, the findings could help advance several emerging quantum technologies.
“These materials could eventually be used for quantum computing communications and quantum sensing, which would help for applications such as healthcare, cybersecurity and improved GPS; and gives us more control over the building blocks needed to get there.”