Charting the quantum world: how JAIST aims to unlock the power of electron spin

Magnetism at its most fundamental level originates from electron spin, the tiny magnetic momentum carried by each electron. At the Japan Advanced Institute of Science and Technology (JAIST), scientists are exploring how to isolate and control individual electron spins, one at a time. By sensing and controlling these fundamental units, they aim to harness these magnetic signals that could revolutionize data storage, enable new types of sensors, and even power the quantum computers of the future.

The An Laboratory on Quantum Sensing and Imaging
Inside the Laboratory on Quantum Sensing and Imaging at JAIST, Associate Professor Toshu An and his students are building several tools to make the invisible world of spin dynamics come to life.

Assoc. Prof. An pursued his education and obtained training and work experience at multiple institutions across Japan and Europe. His research topics evolved from surface science to spintronics and scanning probe microscopy, ultimately focusing on quantum spin physics.

"I moved around six or seven different places and experienced so many different environments. That also indicates that my research topics changed three or four times. But now, finally, all the experiences have come together. Everything finally has a meaning," Assoc. Prof. An reflects.

Assoc. Prof. An’s work revolves around the science of electron (and nuclear) spin. “Magnetism comes from the electron. Each electron has a property called spin, and that spin behaves like a tiny magnet,” explains Assoc. Prof. An.

Spin dynamics refers to how these tiny magnets fluctuate, precess, move, and interact over time. Understanding and controlling this motion at the nanoscale opens the door to entirely new technologies.

‘Sen Tan’ edge of quantum research at JAIST
At JAIST, Assoc. Prof. An’s team focuses on detecting, controlling, and imaging spin dynamics using one of the most sensitive quantum sensors available today, the nitrogen-vacancy (NV) center in diamond. An NV center is a tiny defect in a diamond crystal formed by a nitrogen atom next to a missing carbon atom. This defect hosts an effective quantum spin system that behaves like a nanoscale magnet.

“NV center in diamond works like a compass. If there is an external magnetic field, this small magnet responds to it,” says Assoc. Prof. An.

Twenty years ago, observing a single spin required cooling materials to a temperature down to liquid helium temperature (4.2 K). Today, using NV centers, researchers can read out spin states at room temperature and at atmospheric pressure conditions.

By attaching nanoscale diamond sensors to scanning probes and moving them with nanometer precision using piezo scanners, the laboratory effectively builds nanoscale magnetic imaging systems.

"We can scan and control this diamond at the nanometer scale by using a piezo scanner. We attach a diamond hosting NV center to a scanning probe and then move it around to detect very local electron and nuclear spins and to image ferro magnetic and paramagnetic structures, molecules, and biomaterials" he explains.

To broaden the applications of the sensors, the laboratory also explores hybrid spin systems, where spins communicate with one another. For instance, they succeeded in exciting an NV center from a significant distance of 3.6 millimeters using spin waves, opening up an entirely new system to study spin interactions.

"This will be a new framework to study the interactions of hybrid spin systems, opening possibilities for coupling quantum sensors over macroscopic distances, even applicable in future quantum computing, and quantum networks” notes Assoc. Prof. An.

Looking ahead, one of their long-term goals is to establish nanoscale magnetic resonance imaging (MRI) technique.

The conventional MRI in hospital machines works by detecting the nuclear spins of hydrogen atoms in water to image the human body. The NV center does the same thing, but at a much smaller scale. In the hospital MRI machines, the resolution is limited to micrometers. Using the same principle with this diamond sensor, Assoc. Prof. An’s group aims to achieve nano-MRI with the NV center, aiming for nanometer-scale resolution.

Such nanoscale magnetic sensing could one day enable molecular-scale studies in biology and chemistry, or highly resolved investigations of electronic and magnetic behavior in advanced materials.

Global collaborations
Collaboration is key to achieving such pioneering milestones. Assoc. Prof. An has worked with researchers in the United States, Germany, and across Europe, and maintains ties with global leaders in quantum sensing and NV-center–based technologies.

Two years ago, one of his doctoral course students spent six months at the University of Munich in Germany. Assoc. Prof. An considers such exchanges of resources and knowledge crucial to progress.

The laboratory maintains active collaborations with researchers in the United States and Europe, while also seeking to expand partnerships in Australia, Asia, and South Asia. It actively engages with groups worldwide working on quantum sensing and NV-based technologies.

Assoc. Prof. An also sees Japan’s role as a crucial one, leveraging its world-class standards in materials science. "In Japan, historically and traditionally, there are many researchers who are good at making very pure, high-quality diamonds. We have craftsmanship, and that is Japan's advantage," says Assoc. Prof. An.

Research environment at JAIST
The university provides an environment that Assoc. Prof. An considers ideal for their research. "JAIST is equipped with a very high standard of facilities that we can use."

Moreover, he deeply values the freedom and flexibility the institute provides. "Most professors and associate professors are kind of independent. We have more freedom to do things. If I have a new idea, I can pursue it."

Second is the emphasis on education. "After coming here, I found that not only research but also education for master's and doctoral students is very well structured. Students and professors can study again and become more knowledgeable. This is a cutting-edge research institute that also emphasizes education—an exceptionally good combination."

The technical infrastructure supports both local research and international collaboration. Students and faculty can freely use high-performance computing resources, enabling them to conduct research more freely and collaborate with partners overseas.

Training the next generation of quantum scientists
Beyond the cutting-edge research output, JAIST is also building a new generation of researchers in interdisciplinary science.

For those passionate about this field, Assoc. Prof. An welcomes students from diverse backgrounds. "Everybody is welcome. As long as students are interested in something, they can find a field that matches their interest."

Students in the laboratory come from diverse backgrounds such as physics, engineering, programming, and even bio-related fields.

"Our work connects to physics, applied physics, bio-related applications, chemistry, computing, and engineering. If they love deep physics, that is fine. If a student is interested in engineering, including programming, there is place for them. If they are fascinated by chemistry and biology, our sensor may one day be used to study molecular systems and biomaterials."

Shaping the quantum future: The broader vision for spin systems
All these efforts are connected by a single vision: to understand the fundamental physics of spin dynamics and translate that understanding into practical technologies.

Assoc. Prof. An concludes, “This NV center is currently used as a quantum sensor. However, by preparing multiple NV centers rather than just one, they may together function as quantum bits for a quantum computer at room temperature. In the biomedical field, nanoscale MRI could visualize individual molecules and their interactions. In chemistry, it could reveal reaction mechanisms at the atomic level. In materials science, it could map current flow in batteries and electronic devices with unprecedented resolution.

The pioneering work being pursued by Assoc. Prof. An and his research group paves the way for translating spin dynamics into novel, usable technologies.

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About Japan Advanced Institute of Science and Technology, Japan
Founded in 1990 in Ishikawa prefecture, the Japan Advanced Institute of Science and Technology (JAIST) was the first independent national graduate university in Japan that has its own campus to carry out research-based graduate education in advanced science and technology. The term “Advanced” in JAIST’s name reflects the Japanese term “Sen Tan,” meaning “cutting-edge,” representing the university’s focus on being at the forefront of innovative research and education. Now, after 30 years of steady progress, JAIST has become one of Japan’s top-ranking universities. JAIST aims to foster capable leaders through its advanced education and research curricula. About 40% of JAIST’s alumni are international students. The university has a unique style of graduate education to ensure that students have a thorough foundation to build cutting-edge research and technology in the future. JAIST also works closely with both local and overseas academic and industrial communities, promoting industry–academia collaborative research.

Website: https://www.jaist.ac.jp/english/