Tokyo Institute of Technology achieves world's highest sensitivity low-frequency magnetic field measurement with diamond quantum sensor

A research group of Specially Appointed Associate Professor Naota Sekiguchi, Associate Professor Takayuki Iwasaki, and Professor Mutsuko Hatano of the Tokyo Institute of Technology's School of Engineering, the University of Tokyo, the Research Center for Electronic and Optical Materials at the National Institute for Materials Science (NIMS), the Quantum Materials and Application Research Center at the Takasaki Institute for Advanced Quantum Science of the National Institutes for Quantum Science and Technology (QST) and the Ministry of Education, Culture, Sports, Science and Technology, Japan has announced that they have achieved a magnetic field sensitivity of 9.4 pT/√Hz for low-frequency magnetic fields with a diamond quantum sensor using nitrogen-vacancy centers (NV centers) in the diamond. This was realized by synthesizing a high-quality diamond with a long spin dephasing time, which determines the magnetic field sensitivity, and using it to reduce noise to the quantum mechanical limit. This sensor is expected to be applied for the magnetic measurement of brain activity as it does not require large and costly equipment such as magnetic shields and coolants. The results were published in the international journal Physical Review Applied on June 5.

As diamond quantum sensors can realize highly sensitive measurements at room temperature even under strong magnetic fields, they are expected to be applied for the magnetic measurements of brain activity as they do not require large and costly equipment such as magnetic shields and cooling devices.

In this study, the research group developed a diamond quantum sensor designed to easily approach the measurement target. It is expected that, in the future, a brain-machine interface will be developed for social implementations such as routine checkups of brain activity. The highest sensitivity for a single diamond quantum sensor without a magnetic flux concentrator is achieved in the low-frequency range. The developed sensor exhibits excellent stability and is confirmed to continue operation with high sensitivity for at least 200 minutes. In the future, they aim to demonstrate magnetoencephalography using the developed diamond quantum sensor on animals.

Sekiguchi said, "The realization of a high sensitivity diamond quantum sensor, which has various excellent features, is a big step toward applications such as everyday magnetoencephalography. We will continue to explore ways to achieve even higher sensitivity and practical applications in the future research."

Journal Information
Publication: Physical Review Applied
Title: Diamond quantum magnetometer with dc sensitivity of sub-10 pT Hz^-1/2 toward measurement of biomagnetic field
DOI: 10.1103/PhysRevApplied.21.064010