My favorite saying: Nobody will pay attention to you if you only do trivial things.

Q: Why did you choose this saying?

This may sound like the opposite of a favorite saying. I guess here at Researchers' Voice we're supposed to present some kind of motto, but there's a reason I'm sharing this negative saying with you. These words resonate with me, and I think it's worth sharing them with young researchers as a life lesson for researchers.

This saying is something that one of my professors told me and other graduate students when I was in graduate school. In essence, this is advice to not waste your time getting stuck on trivial research topics that are unlikely to get any attention from your peers. Maybe my professor should have phrased this a bit more delicately, but I think it was a good lesson in the harsh realities of the world of research.

Research is, in a sense, a never-ending activity. There are always more things to be learned. Researchers use their limited resources to discover something new or find a partial solution to some problem, and then they pass it on to other researchers, who add their own ideas and discoveries. Each individual researcher conducts research driven by their own intellectual curiosity, but if your research is not of interest to other researchers and doesn't expand the circle of research—or, to put it harshly, if it ends up being nothing more than self-satisfaction—other researchers are not going to welcome you with open arms, nor will it help promote you.

Research itself is a specialized activity, so, generally speaking, those who best understand the significance of the study are other researchers in the same field. In this sense, once you decide to do a study, you should do one that's good enough that five or ten years later, researchers in your field are still saying, "this was a significant study" or "this study helped this field grow." It hurts, but I sometimes ask myself, "Am I just sticking to a tiny topic and telling myself that I'm doing something good?"

Q: What kind of research are you doing?

I am doing research in theoretical physics, particularly quantum mechanics—the physical laws of the microscopic world. I also like classical mechanics, which are the laws of physics that govern the macroscopic world. So, I do research on both quantum and classical mechanics. Quantum mechanics, being microscopic, and classical mechanics, being macroscopic, are completely different theories, but in the real world, microscopic atoms and electrons combine to form macroscopic objects such as living bodies and celestial bodies. From this perspective, I believe that quantum mechanics and classical mechanics are theoretically and mathematically related. Therefore, my life's work is to establish a theory that encompasses both types of mechanics. 

Q: How did you get into this research?

When I was in my third year of university, I read a book called "The Character of Physical Law" by Richard P. Feynman. This book explains already known physical laws, but in the last chapter, the author discusses what he expects for the future of physics, the gist of which was this: "In the future, I expect one of two things to happen: Either physics will reach its final conclusion after all physical laws have been completely clarified; or physics will stop its progress after 99.9% of physical laws have been clarified, leaving only the difficult questions. Now is the time when we can make discoveries in physics." I read this and decided that I, too, wanted to discover something in physics.  

Q: When do you feel excited in your research?

There are moments when several ideas that seemed to exist separately suddenly all come together. This example might be a bit technical, but one such moment was the discovery that the mathematical reason explaining the violation of Bell inequalities (this reasoning is behind the work awarded the 2022 Nobel Prize in Physics) is the non-commutativity of local operators, and that other concepts such as weak value and quantum erasure are also connected by non-commutativity. Such moments make me feel like something that had been hazy and indistinct has suddenly become quite clear.

Q: The 2022 Nobel Prize in Physics* was awarded to three researchers in the field of quantum mechanics. Shortly after the winners were announced, you spoke about quantum mechanics at a press conference held at Nagoya University. Can you tell us anything about that?

I had been tapped as the person who would give a comment or explanation on the day of the announcement in the event that someone I knew personally was selected as a Nobel laureate in physics (especially if that person ended up being Japanese), so, in my laboratory, I kept a close eye on the proceedings online. A member of the Nobel Committee announced, "This year’s prize is about the power of quantum mechanics." That really hyped me up—"Wow, the prize is going to quantum mechanics! Is this it?!" Then they read out the names of Alain Aspect and John Clauser, and I shouted with joy, "I finally guessed right!" I had no idea who the third recipient would be, but when it was announced that it was Anton Zeilinger, I dare say I thought he was the right choice.

After I finished listening to the Nobel Committee's explanation, just as I was feeling relieved that there was nothing for me to do at that moment (or so I thought), the phone rang in my laboratory. The person on the other end of the line said to me, "Reporters have gathered in Toyoda Auditorium Symposion Hall [in Nagoya University], so please go and explain quantum mechanics to them." At first I thought, "What? Me?" but in the next moment, I intuitively realized that I should not refuse. So I said, "Yes, I'll be there." I put my business cards and the books I had written in my backpack and was about to leave my laboratory when the phone rang. It was someone from a newspaper, asking me for a rough outline of the award-winning research. I gave an explanation, then rushed out of the laboratory. I apparently ended up keeping the reporters waiting so long that someone from the administrative office went to wait for me outside the auditorium. It was the kind of experience that you might never have even once in your life—very exciting.

* Nobel Prize Outreach website: https://www.nobelprize.org/prizes/physics/2022/summary/

Q: How do you spend your days off? What do you do to recharge?

I play with my daughter, who is a first-grade student in elementary school (as of December 2022). Recently, I feel like that's sucking up all of my energy.
My family and I attended an event at the Nagoya University Museum where we tried making crystals of bismuth and alum.

My weekend work is playing with my daughter.

Q: What are some of the big influences in your life? This might be people, books, things,  events—anything that's influenced you.

I think I have been influenced by three works: "Quantum Mechanics," a book written by Sin-itiro Tomonaga, which my physics teacher Hideki Murai gave me when I graduated from high school; Richard P. Feynman's book, "The Character of Physical Law," which I read in my third year at Nagoya University's School of Engineering; and "The Reality of the Quantum World," an article explaining Aspect's experiments written by Abner Shimony (a co-researcher of Clauser) and published in Nikkei Science (the Japanese version of Scientific American) that I read as part of then-Associate Professor Arao Nakamura's class. All of these contributed to the person I am today.

In addition, when I was a student, I belonged to the Wandervogel Club, where I took part in outdoor activities such as mountain climbing, biking, and river rafting. These were also wonderful experiences, and they taught me how insignificant my physical and intellectual strength is in the vast expanse of nature.

Q: What are your goals and ambitions for the future?

I still have a lot of topics I want to do research on and write about in papers and books. I have devoted myself to physics, but now I have a plan to work with artificial intelligence to pioneer a new science. I want to do this as soon as possible. I also want to find more opportunities to show children and young people the fun of science and encourage them to take part in scientific research.