Cambridge scientists achieve long-sought quantum state stability in new 2D material

Researchers at the Cavendish Laboratory have identified spin coherence in atomic defects within hexagonal boron nitride (hBN) at ambient conditions, a rare achievement in quantum materials. The study, published in Nature Materials, points out that these spins can be controlled with light and have promising implications for future quantum technologies, including sensing and secure communications. The findings also highlight the need for further exploration to increase defect reliability and extend the spin retention time, underscoring the potential of hBN in advancing quantum technology applications. Credit: Eleanor Nichols, Cavendish Laboratory

Scientists at the Cavendish Laboratory have discovered spin coherence in hexagonal boron nitride (hBN) under normal conditions, offering new perspectives for quantum technology applications.

Cavendish Laboratory researchers have discovered that a single ‘atomic defect’ in a material known as Hexagonal Boron Nitride (hBN) retains spin coherence at room temperature and can be manipulated using light.

Spin coherence refers to an electronic spin that is able to preserve quantum information over time. The discovery is important because materials that can have quantum properties under ambient conditions are quite rare.

Findings published in Materials of Nature, further confirm that the accessible spin coherence at room temperature is longer than the researchers first thought it might be. “The results show that once we write a certain quantum state into the spin of these electrons, this information is preserved for ~1 millionth of a second, making this system a very promising platform for quantum applications,” said Carmem M. Gilardoni, co. -author of the paper and Rubicon postdoctoral student at the Cavendish Laboratory.

“This may seem short, but the interesting thing is that this system does not require special conditions – it can maintain the spin quantum state even at room temperature and without the need for large magnets.”

Properties of hexagonal boron nitride

Hexagonal Boron Nitride (hBN) is an ultra-thin material composed of a clustered array.atom-thick layers, like sheets of paper. These layers are held together by the forces between the molecules. But sometimes, there are ‘atomic defects’ within these layers, similar to a crystal with molecules trapped within it. These defects can absorb and emit light in the visible range with well-defined optical transitions, and they can act as local traps for electrons. Because of these ‘atomic defects’ within hBN, scientists can now study how these trapped electrons behave. They can study the property of spin, which allows electrons to interact with magnetic fields. What’s really exciting is that researchers can control and manipulate electron spins using light inside these defects at room temperature.

This discovery paves the way for future technological applications, especially in sensing technology.

However, since this is the first time anyone has reported the spin coherence of the system, there is much to investigate before it is mature enough for technological applications. Scientists are still figuring out how to make these bugs even better and more reliable. They are currently investigating how far we can extend the spin conservation time and whether we can optimize system and material parameters that are important for quantum-technology applications, such as defect stability over time and light quality emitted by this defect.

Future perspectives and concluding remarks

“Working with this system has shown us the power of fundamental investigation of materials. As for the hBN system, as a field we can exploit excited state dynamics in other new material platforms for use in future quantum technologies,” said Dr. Hannah Stern, first author of the paper, who conducted this research. at the Cavendish Laboratory and is now a Royal Society University Researcher and Lecturer at the University of Manchester.

In the future, the researchers are looking at further development of the system, exploring many different directions from quantum sensors to secure communications.

“Each promising new system will expand the toolkit of available materials, and each new step in this direction will advance the scalable implementation of quantum technologies. These results demonstrate the promise of layered materials towards these goals,” concluded Professor Mete Atature, Head of the Cavendish Laboratory, who led the project.

Reference: “A coherent quantum spin in hexagonal boron nitride at ambient conditions” by Hannah L. Stern, Carmem M. Gilardoni, Qiushi Gu, Simone Eizagirre Barker, Oliver FJ Powell, Xiaoxi Deng, Stephanie A. Fraser, Louis Follet, Chi Li, Andrew J. Ramsay, Hark Hoe Tan, Igor Aharonovich and Mete Atatüre, 20 May 2024, Materials of Nature.
DOI: 10.1038/s41563-024-01887-z