Researchers at the University of Technology Sydney have demonstrated a new way to control tiny quantum light sources by twisting atomically thin layers of hexagonal boron nitride.
This advance provides scientists with a new way to tune quantum emitters. Quantum emitters are tiny light sources that could play a key role in future technologies such as quantum computing, secure communications, and ultra-sensitive sensors.
Lead author Dr Angus Gale said the study provides researchers with a valuable new tool to make these quantum systems more practical.
“We can measure these quantum emitters and confirm their existence, but it’s difficult to actually make them work. This gives us a lever to get closer to it. This is a step towards realizing quantum technology,” Dr. Gale said.
Twisting the layers changes the quantum light
During the experiment, Gale and his team discovered that twisting the material can significantly change both the color and wavelength of the light emitted by the quantum emitter. The magnitude of the change was particularly noteworthy.
Most studies create devices with a specific twist angle and leave it unchanged. In contrast, the researchers were able to repeatedly lift, rotate and reload the material, continuously changing its properties.
“We take advantage of 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 emitter. You can’t really do that with traditional materials like diamond or silicon carbide.”
“The advantage is that you can use this twistable platform to shift emissions very significantly,” Gale said. “When controlling these systems, the amount of manipulation is often very limited, but in this case the changes were much larger than expected.
“Rather than making the defects in hBN behave like a traditional solid host, we took advantage of hBN’s own strengths: its thin, layered, and twisted structure.”
Why hexagonal boron nitride is different
Gale likened the material’s structure to a slice of cheese rather than a solid block.
“With block cheese, you can’t really get to the flavor in the middle. But with slices, you can peel back the layers and put them back together to change the interaction,” he said.
Because hBN is made of extremely thin layers, researchers can separate and reassemble these layers in ways not possible with traditional quantum materials.
New possibilities of quantum technology
Supervisor Professor Igor Aharonovitch said the ability to twist layered materials was particularly interesting because it could reveal entirely new physical behaviors.
“If you take two layers that don’t do much on their own and put them together at a certain angle, you suddenly have a completely different system,” Professor Aharonović says.
The discovery could help advance several new quantum technologies, Aharonovitch said.
“These materials could eventually be used in quantum computing communications and quantum sensing, which could help with applications such as healthcare, cybersecurity, and improved GPS, giving us more control over the building blocks needed to get there.”
