Quantum sensors detect the smallest of environmental changes - for example, an atom reacting to a magnetic field. As these sensors "read" the unique behaviors of subatomic particles, they also dramatically improve scientists' ability to measure and detect changes in our wider environment.
Monitoring these tiny changes results in a wide range of applications - from improving navigation and natural disaster forecasting, to smarter medical imaging and detection of biomarkers of disease, gravitational wave detection, and even better quantum communication for secure data sharing.
Georgia Tech physicists are pioneering new quantum sensing platforms to aid in these efforts. The research team's latest study, "Sensing Spin Wave Excitations by Spin Defects in Few-Layer Thick Hexagonal Boron Nitride" was published in Science Advances this week.
The research team includes School of Physics Assistant Professors Chunhui (Rita) Du and Hailong Wang (corresponding authors) alongside fellow Georgia Tech researchers Jingcheng Zhou, Mengqi Huang, Faris Al-matouq, Jiu Chang, Dziga Djugba, and Professor Zhigang Jiang and their collaborators.
An ultra-sensitive platform
The new research investigates quantum sensing by leveraging color centers - small defects within crystals (Du's team uses diamonds and other 2D layered materials) that allow light to be absorbed and emitted, which also give the crystal unique electronic properties.
By embedding these color centers into a material called hexagonal boron nitride (hBN), the team hoped to create an extremely sensitive quantum sensor - a new resource for developing next-generation, transformative sensing devices.
For its part, hBN is particularly attractive for quantum sensing and computing because it could contain defects that can be manipulated with light - also known as "optically active spin qubits."
The quantum spin defects in hBN are also very magnetically sensitive, and allow scientists to "see" or "sense" in more detail than other conventional techniques. In addition, the sheet-like structure of hBN is compatible with ultra-sensitive tools like nanodevices, making it a particularly intriguing resource for investigation.
The team's research has resulted in a critical breakthrough in sensing spin waves, Du says, explaining that "in this study, we were able to detect spin excitations that were simply unattainable in previous studies."
Detecting spin waves is a fundamental component of quantum sensing, because these phenomena can travel for long distances, making them an ideal candidate for energy-efficient information control, communication, and processing.
The future of quantum
"For the first time, we experimentally demonstrated two-dimensional van der Waals quantum sensing - using few-layer thick hBN in a real-world environment," Du explains, underscoring the potential the material holds for precise quantum sensing. "Further research could make it possible to sense electromagnetic features at the atomic scale using color centers in thin layers of hBN."
Du also emphasizes the collaborative nature of the research, highlighting the diverse skill sets and resources of researchers within Georgia Tech.
"Within the School of Physics, Professor Zhigang Jiang's research group provided the team with high-quality hBN crystals. Jingcheng Zhou, who is a member of both Professor Hailong Wang's and my research teams, performed the cutting-edge quantum sensing measurements," she says. "Many incredible students also helped with this project."
Du is a leading scientist in the field of quantum sensing - this year, she received a new grant from the U.S. Department of Energy, along with a Sloan Research Fellowship for her pioneering work on developing state-of-the-art quantum sensing techniques for quantum information technology applications. The prestigious Sloan award recognizes researchers whose "creativity, innovation, and research accomplishments make them stand out as the next-generation of leaders in the fields."
This work is supported by the U. S. National Science Foundation (NSF) under award No. DMR-2342569, the Air Force Office of Scientific Research under award No. FA9550-20-1-0319 and its Young Investigator Program under award No. FA9550-21-1-0125, the Office of Naval Research (ONR) under grant No. N00014-23-1-2146, NASA-REVEALS SSERVI (CAN No. NNA17BF68A), and NASA-CLEVER SSERVI (CAN No. 80NSSC23M0229).
