2022 Honda Prize Commemorative Talk Session: 2020 Honda Prize Ceremony

Award commemorative contents	2022 2021 2020

* Information concerning affiliation/post/profile of the laureate and guests is current at the time he/she received the prize.

Achievement Commentary

Commemorative Talk Session

2022 Honda Prize Commemorative Talk Session

"Curiosity-driven" drives the world.

Dr. Hidetoshi Katori has invented an optical lattice clock that is 1,000 times more accurate than conventional atomic clocks. Dr. Yoichiro Murakami is a councilor for the Honda Foundation and a leading authority on the history and philosophy of science in Japan. These two great minds talked freely about the essential factors needed to create new technology and a sound approach to scientific Development.

Talk Session Member

Yoichiro Murakami Councilors,
Honda Foundation Professor Emeritus,
The University of Tokyo Professor Emeritus,
International Christian University

Dr. Hidetoshi Katori
Professor, Department of Applied Physics Graduate School of Engineering The University of Tokyo,
Chief Scientist Quantum Metrology Laboratory,
Team Leader Space-Time Engineering Research Team RIKEN Center for Advanced Photonics (RAP)RIKEN,
Program Manager

An era in which basic research and technological development overlap

Murakami: The primary keywords to describe your research, Dr. Katori, is “curiosity-driven.” Conventionally, the field of basic science has always been driven by “curiosity,” while engineering research has been “mission-oriented,” aiming to achieve a clear target in an efficient manner. These two fields—basic research and technological development—the latter which applies the results of the former, are now widely overlapping today

One researcher has divided the approaches to research into Mode-1 and Mode-2. Mode-1 research is carried out by a leading researcher from a specific scientific area, who manages a hierarchical group of assistants, postdoctoral researchers, and postgraduates working in the same field. On the other hand, Mode-2 research comprises a network of researchers from different fields working in a horizontal manner towards a single goal utilizing all their capabilities and techniques. It could be said that the former approach carries out basic research while the latter network approach undertakes mission oriented research. However, even this distinction is obscure today.

In such a situation, you focused on optical lattice clocks as your key research area. You must have had a certain attraction to the topic to make you so passionate about the theme.

Katori: It was fortunate that I came across a good research topic, and fortunate again that I could find the directions to fully develop it one after another.

When I started my research into optical lattice clocks, I was thinking to study something else if other people started researching the same topic. However, I could not let it go and kept finding things that I wanted to explore more deeply, one after another

Risk in engage in unpopular research

Murakami: There is an expression “referee bias.” This suggests that the direction taken by a community in a research genre is determined by, for example, a journal referee*. Wasn’t it risky to post your paper on a theme that literally no one was investigating to a research community?

＊Reviewers for academic journals

Katori: When you give a presentation on research that no one else is undertaking at an international conference, only a few members of the audience will understand what it means at the beginning. That is also true for me. When I first learn about a new topic, I cannot understand everything at that point. I gradually gain the whole picture by listening to lectures on the same topic again and again, and then, after listening to the presentations, through discussions with many people. The optical lattice clock went through the same process. After the first presentation, we held a discussion after the conference. In response to someone’s comments on some parts that were difficult to understand, I amended those sections for the following presentations to make them more explanatory. Through such interactions, I gained the understanding of the community on my research direction. When I posted my first paper, a journal referee at Physical Review Letters made a number of severe criticisms. For example, the referee said that my paper had too many self-references. However, I could not make references to other people’s studies as I was the only one working in this approach!

Murakami: There was no one other than you.

Katori: I still rember the pers on a formidable referee. Then I submitted our first experimental results to Nature. The journal’s response was very favorable and decided to publish it in a week or so. When a journal editor recognizes that a certain study is important, he forward the work to referees who would understand the work’s value to accelerate the publishing decision. I think our paper managed to get on that track. The Nature referee gave me a very good review. I was given a comment that overviewed the next five to ten years, which we were not serious about at that time. “Your paper discusses the development of a clock with 18-digit accuracy—but where can this experiment be conducted? An experiment on a conventional optical table is not a likely candidate due to the thermal expansion.”

Murakami: That is a very nice story.

The start was “non-competitive research”

Katori: I believe the scientific community is fundamentally friendly. However, it becomes unfriendly when the competition to reach the same target is tough, as it becomes difficult for journal editors and reviewers to make unbiased judgments in relation to the researchers. Because I was the only person who was seriously researching optical lattice clocks, scientists agreed to review my paper saying that they

wanted to see how interesting it was. I think it was fortunate that I could start my research without any competition.

Murakami: I hope that young researchers can hear what you have said. I believe that an over-competitive environment has a negative effect on people.

Katori: When I first looked for research topics, my idea was “conducting research that is noncompetitive, fun, and enjoyable for us. "That was my starting point.

However, research must be beneficial. I thought, “If I carry out the basic research now, it has to produce some results that could contribute to society in 20 years.” This awareness was reinforced as I grew older. I am pleased that my 20 years of research has

now progressed to the stage where it could lead to a social contribution. It is a long time since the days when I was a young researcher who wanted to say something bold in an international conference where I was faced by a row of established master researchers.

Murakami: To obtain funding for scientific research—even for a general area—researchers today are required at an early stage to show how their work could contribute to society. I find this trend too demanding.

Katori: I think researchers in their 30s, those who have just completed their doctoral course, can feel free to conduct their research. On the other hand, those in their 50s and 60s must (experienced researchers should) aim at something beneficial to society or at further advanced research, based on their past 20 years of work.

Murakami: I understand that this is the time when researchers must think about the impact—both positive and negative—of their research on society. However, I am afraid that forcing young researchers to remain conscious of the social benefits of their

studies may hinder true “curiosity-driven” research.

I have heard that there are now people who are already applying the results of the optical lattice clock research to practical uses in society.

Katori: The optical lattice clock enables a new relativistic way for space-time sensing. I am wondering how we can use it. Therefore, I’m

currently discussing with young researchers areas where positioning based on the optical lattice clock has advantages over the Global Navigation Satellite System (GNSS).

Significance of making technology a black box

Murakami: In your commemorative lecture at the award ceremony, you mentioned that “the achievements of the first optical lattice clock suddenly increased the number of researchers across the world.”

Katori: When I saw a session entitled “optical lattice clocks” in an international conference on precision measurement in 2006, I felt happy that the field of optical lattice clocks had been recognized.

Now there are a number of international conferences related to optical lattice clocks.

To tell the truth, the reason why research into optical lattice clocks has grown is mainly because “it is achievable if one tries as described in the papers.” Creating an optical clock by trapping a single-ion was once the strongest candidate for next-generation precision time measurement; however, this method is difficult to reproduce as it involves elaborate skills that are inherited in the laboratory.

Murakami: Does this mean it is technically difficult to achieve?

Katori: That’s right. Not everybody can reproduce this. One of my motivations in investigating the optical lattice clock was because I thought it would be easier in the future if I could design the clock eliminating such a technical structure. Many people were then able to start research because the clock design no longer depended on technological details.

The other driving force was the timing—it was a moment of generational change within the clock study groups.

Rather than continuing research into single-ion optical clocks, starting a new research topic may have been easier for the younger researchers.

Murakami: Your research attracted young people. I envy you as a researcher!

Katori: Now we are facing the challenge of downsizing the optical lattice clock for practical use in society. Technology that needs the involvement of physicists would not be able to spread widely into other fields. I would like to make our clock technology a complete black box so that geodetic or geophysical researchers can find new applications freely.

Murakami: You mean “blackboxing.”

Katori: I think making technology into a black box is very important to spread applications across society.

Downsizing for practical usage is almost the equivalent of eliminating the necessity of human intervention. However, a black box cannot be

amended later, therefore it takes a long time to make one. I can imagine that it would be difficult for young researchers to work on blackboxing, so people in my generation must do it.

Murakami: I agree with you that people in the same position as yourself should take care of that process, and, in fact, you are actually leading it.

Katori: The optical lattice clock enables us to see relativistic space-time but this fact itself does not do anything. However, if this capability is blackboxed as a readily available technology, it could be combined with other technologies, which may in turn lead to a completely new future that could never have been imagined. This is the area which I would like the younger generation to explore.

Murakami: In his final days, the late Mr. Soichiro Honda said sadly: “When I visit the factories, I cannot understand the cars of today.” That was just at the time when a range of automotive components were being turned into black boxes. Blackboxing may be one of the seeds for new inventions.

Something that gladdens my heart when talking with you is that you have great expectations for young people.

Katori: I do have expectations of young people but I feel their motivation has changed.

Murakami: Certainly it seems that the number of young people with ambition is declining. Yet I cannot say that it is acceptable to have blatant competition like submitting a paper that could take the researchers closer to the Nobel Prize with a cunning method to outsmart competitors, as was seen in the field of molecular biology at one time. Physics may not have such a strong presence in recent years, but

your work, Dr. Katori, has shown us that there are still many more interesting topics to be explored in physics.

Katori: It is hard to work in a mature field. When I was in Germany after becoming a researcher, I wondered for a while, “why did I choose physics?”

because I felt that there was such a large unknown area to explore in the life sciences.

Murakami: Talking of the Nobel Prize, Einstein did not receive the prize for his theory of relativity in 1921. Yet after 100 years, that again becomes a focus of attention because of your work. This is why academic pursuits are so fascinating.

Award commemorative contents	2022 2021 2020