Reviewed by Danielle Ellis, B.Sc.Oct 3 2024
Researchers at Purdue University have created one-dimensional boron nitride nanotubes (BNNTs) with spin qubits, or spin defects, that are pending patent. Compared to conventional diamond tips used in scanning probe magnetic-field microscopes, BNNTs exhibit higher sensitivity and high resolution in the detection of off-axis magnetic fields. The research was published in the journal Nature Communications.
Tongcang Li is in charge of the group that created the BNNTs using optically active spin qubits. He teaches at Purdue Quantum Science and Engineering Institute as well. The group comprises Purdue graduate students Xingyu Gao, Sumukh Vaidya, and Saakshi Dikshit, who are the Co-authors of the research.
BNNT spin qubits are more sensitive to detecting off-axis magnetic fields than a diamond nitrogen-vacancy center, which is primarily sensitive to fields that are parallel to its axis, but not perpendicular. BNNTs also are more cost-effective and offer more resilience than brittle diamond tips.
Tongcang Li, Quantum Science and Engineering, Purdue University
Applications for BNNTs include quantum sensing, which gathers and processes data at the atomic level while measuring variations in magnetic fields.
They also have applications in the semiconductor industry and nanoscale MRI, or magnetic resonance imaging.
Xingyu Gao, Graduate Student, Purdue University
The Purdue Innovates Office of Technology Commercialization has applied for patents to protect intellectual property after Li revealed the nanotube spin qubits to them.
Testing and Developing BNNT Spin Qubits
The system was tested using a specially constructed laboratory setup, comprising lasers, detectors, and signal generators to regulate the quantum state of the nanotube spin qubits.
These BNNT spin qubits are sensitive to magnetic fields and exhibit optically detected magnetic resonance. When exposed to a magnetic field, the energy levels of the spin qubits within the BNNTs are altered, which can be measured using light.
Sumukh Vaidya, Graduate Student, Purdue University
In the initial demonstration, BNNTs and diamond tips performed similarly.
“Since the boron nitride nanotubes are spatially much smaller than the diamond tips, we expect to be able to achieve superior numbers for the system,” said Dikshit, a Graduate Student from Purdue University
According to Li, the Purdue researchers want to enhance the BNNT spin qubit system's magnetic field sensitivity and spatial resolution. These advancements may allow quantum sensing of atomic-scale phenomena.
Vaidya said, “This would enable a very high-resolution scanning of the surface magnetic properties. By improving the sensitivity, we can either get more precise information or achieve faster readout of the external magnetic fields, both of which have applications in quantum science, memory storage, medical and semiconductor industries.”
The Gordon and Betty Moore Foundation and the National Science Foundation supported Li and his team in conducting the study.
Journal Reference:
Gao, X., et al. (2024) Nanotube spin defects for omnidirectional magnetic field sensing. Nature Communications. doi.org/10.1038/s41467-024-51941-2.