Reina Maruyama

Zierler:

Okay. This is David Zierler, oral historian for the American Institute of Physics. It is August 25th, 2020. It's my great pleasure to be here with Professor Reina Maruyama. Reina, thank you so much for joining me today.

Maruyama:

Thank you, David.

Zierler:

Okay, so to start, would you tell me please your title and institutional affiliation?

Maruyama:

I am an associate professor of physics at Yale University.

Zierler:

Okay. And you have some other affiliations with the Quantum Institute?

Maruyama:

Yes. I have a secondary appointment in the astronomy department, and I am also a member in the Yale Quantum Institute. And this year, I'm chair elect for the Yale's Women Faculty Forum.

Zierler:

Oh, the Yale's Women Faculty Forum. And this represents all academic disciplines at Yale?

Maruyama:

That's right.

Zierler:

How long has the forum been in existence?

Maruyama:

The forum started in 2001 at the tricentennial celebration of Yale's existence. And at that time it was deemed that we still needed a forum for women faculty to get together.

Zierler:

Perhaps in some ways more than ever, right?

Maruyama:

(laughs) Right.

Zierler:

How were you asked to chair this committee? Is it passed down from one former chair to another?

Maruyama:

Yes. There's been a series of very strong chairs, and so I was very honored to be asked to be in that line of chairs to lead this group.

Zierler:

And is the mandate sort of open-ended? Or does it focus specifically on things like tenure considerations, making sure that there's a culture of inclusivity? What kinds of things are available to discuss in this forum?

Maruyama:

Yes. The chairs have quite a bit of leeway into what gets focused on that particular year or the years that they're chair. This year we are focusing on making Yale more inclusive, where more people of color and faculty of color feel they belong here. We will focus on continuing to build up a community, which I believe will help in faculty retention. And then after I accepted to serve, COVID hit, and (laughs) so this brings into light how unstable the social structure that enables women to work at all. Now more than ever, we are seeing the urgent need to listen, support one another, and act. COVID has revealed, in gender equity at Yale, what we physicists might call an ‘unstable equilibrium’ where one little nudge can topple over our carefully crafted balance.

Zierler:

Absolutely.

Maruyama:

This will be a big focus for our work this year.

Zierler:

Absolutely. Particularly for those with kids, and the expectation that the kids are home, they're learning remote, and yet we still have our jobs to do, and...

Maruyama:

Exactly.

Zierler:

There's been a lot of literature about how these double duties are falling disproportionally on women, and I'm sure this is a challenge where Yale is no exception either.

Maruyama:

Exactly. It's a problem all over the United States, in particular.

Zierler:

Right. Right.

Maruyama:

And all over the world really. And it's difficult for all parents, but it is disproportionally falling onto women.

Zierler:

Sure. Well, as I said before, let's talk about happier stuff. Let's go right back to the beginning.

Maruyama:

(laughs) Yes.

Zierler:

Reina, let's start with your parents. Tell me a little bit about them and where they are from.

Maruyama:

I was born in Japan. Both my parents are from Japan, and I lived in Japan until I was 12 years old.

Zierler:

Where in Japan is your family from?

Maruyama:

Both my parents grew up in Kyoto. My father's family moved to Kyoto from right outside of Tokyo when he was young. My father was a businessperson, so he worked in a Japanese corporate culture. And my mother actually comes from an academic family, my great-grandfather was a physicist in Japan.

Zierler:

Really?

Maruyama:

Yes

Zierler:

What was his name?

Maruyama:

Yoshida is the last name, Yoshida Usaburo.

Zierler:

Now, did you grow up knowing about his career and his contributions? Was that part of your story as well?

Maruyama:

I did not know he was a physicist until after I had decided to major in physics in college. I knew he was a pretty important person. There were photos of him all around my maternal grandparents' house. I learned he was a professor of physics at Kyoto University when I told my grandmother I wanted to study physics. It was a funny coincidence

Zierler:

Do you know what his field was? What he was interested in?

Maruyama:

He did some spectroscopy. I looked up his papers, and he was studying “effects observed by Mr. Stark” in hydrogen (laughs) and helium. We call these effects “Stark shift” now. He then went on to study condensed matter at Kyoto University. Before he became a professor he actually came over to the United States and to Europe. This was in the 1920s – in '22, '23. Really interesting time in physics. He spent a year in Richardson’s lab in London, learning ways of the West and physics of the West (Richardson later won the Nobel Prize in 1928 for his work on the thermionic emission of electrons from hot wires). We have some of his notes from that time. My great-grandfather then went back to Japan and became a professor at Kyoto. You might find it interesting to know we also have a letter from Yukawa to my great-grandfather (Zierler: Wow.) letting him know that he was--

Zierler:

Now I'm a nerd, so I appreciate the import of this. For the audience out there, that's a very big deal. (laughs)

Maruyama:

Yes. It's interesting. My great-grandfather sponsored Yukawa to go over to Europe so he could learn what was happening that time. This was 1939. The letter from Yukawa to my great-grandfather says that Yukawa has to come back to Japan because the war is breaking out, and that he will come home via Panama Canal. In other words, he came across the Atlantic from Europe to New York, went down to Panama Canal, and went back to Japan. I didn't know any of this as a child growing up. I just knew that my great grandfather was kind of an important person. So, when I decided to major in physics as an undergrad at Columbia and I told my grandmother about it, she (Zierler: Opened up.), she said, "Hang on." (both laugh) "Hold on, sit tight." And she came out with a couple of introductory physics books in Japanese that my great-grandfather had written, and she gave those to me.

Zierler:

That's so amazing that you independently wanted to pursue physics, not really appreciating at all your family legacy in this regard.

Maruyama:

It was a--

Zierler:

It almost seems like there's got to be like a genetic component to that, it's like it's in the blood.

Maruyama:

Yes. Or in education of how the family is relating to me-- but yes, something about it. But it's fun to look back on.

Zierler:

Now, you said your father worked in the corporate world. Did your mother work outside the house?

Maruyama:

She stayed at home when we were younger, but she--

Zierler:

And "we" is who? You have siblings?

Maruyama:

Yes, I have a younger brother. After we came to the United States, my mother got a degree in teaching foreign languages. She had been doing this already in Japan, to teach English in Japan. But after we came over here, she got a degree and then started teaching Japanese at Columbia University.

Zierler:

So the whole family came over when you were 12?

Maruyama:

Yes. The company my father worked for at the time transferred him to their office in New York. Many Japanese corporations do this, where they'll send out people overseas. Especially in the 80s, this was happening a lot. Initially, we were planning to go back after five years. In those five years, I went to middle school and high school, and at the end of the five years, I think both my parents decided that we would stay on in the United States so that my brother and I could continue to be in the United States. I think they liked it here too.

Zierler:

So the idea was, when you left, you were thinking maybe that you would go back to Japan? At least as a 12-year-old, that was the idea?

Maruyama:

That was the idea, yeah. And then we got very much used to the way things are here, and I don't know, maybe my parents thought that there was no way my brother and I would survive in Japan. (laughs).

Zierler:

How did you feel? Do you remember how you felt as a 12-year-old about the prospect of, not only coming to the United States, but New York of all places?

Maruyama:

We moved to Connecticut actually, so it was not like we move to the middle of a city. But I was pretty excited when we came over here--

Zierler:

How was your English at the time?

Maruyama:

I didn’t speak any English. (laughs)

Zierler:

Really?

Maruyama:

I spoke no English and that was frightening, but I think since our family was together, and because both my parents were in the United States as exchange students when they were in high school and both spoke English, I felt confident that they would pull me through whatever was going to happen.

Zierler:

Now, did you take formal English classes? Or watching TV and making new friends was all you needed basically?

Maruyama:

Yes, I spent a year really absorbing the language, trying to understand what was going on around me. It was probably two years before I was much more comfortable speaking English. That was 7th and 8th grade. And when 9th grade hit, and we were supposed to read Great Expectations, you know, Charles Dickens, (laughs) Romeo and Juliet, and so on… That was challenging, I remember. And I remember popping a book on tape, cassette tape, as my teacher recommended to get through these English classes.

Zierler:

Reina, when did you start to become interested in science? Was this even before you came to the United States? Even before sort of higher level math and science classes? Or did this happen when you got to the United States?

Maruyama:

I think it was a combination of things, but in retrospect I was always interested. I had this amazing teacher in fourth grade. I remember he was the vice principal of the school, but he taught science. He taught us how to use Bunsen burners. I remember this one homework in particular where he asked us, "What is the minimum height of mirror that you need to see all of yourself?" I remember going home and doing experiments with that. These kinds of things-- I always wanted to know how things work. I was often not satisfied with the answers I got from people around me, and I was very interested in finding more about these things. And you know, math and things came fairly easy to me. I think I see it with one of my own kids, I think there's kind of a way that scientists think, and physicists in estimating how things work, breaking down bigger problems into smaller problems to try to understand. It's the ability to make estimates based on information given, I think I always enjoy doing that kind of thing. And then we came to the United States, I didn't speak English, but I could still do math and I could still understand science. So science and music, I think those were the two things that really--

Zierler:

Universal languages.

Maruyama:

Yeah. These things were what I really continued to enjoy.

Zierler:

And what kind of music were you interested in, or are interested in?

Maruyama:

I play the violin. I grew up playing the violin. And that was fun. So there--

Zierler:

That was probably useful to you in terms of getting comfortable in a new school and a new country.

Maruyama:

Yes, Exactly. I had a friend who also played music, and she helped me a lot in the first days. And the school I went to was a really good environment to be in. There were other kids who were also interested in music. I got into that group of friends, and we made music together.

Zierler:

I know what you mean, I'm a double bass player, classically trained. So the orchestra is a safe place in high school. (laughs) No matter where you're coming from. (both laugh)

Maruyama:

Right.

Zierler:

When it was time to start thinking about college for you, was it already clear that your parents were going to stay in the United States? Were you not thinking, you know, time to head back to Japan for school?

Maruyama:

Yes, I think by then we had decided to stay here, so I knew I would apply to colleges in the United States.

Zierler:

And where did you apply?

Maruyama:

Everywhere. (both laugh)

Zierler:

Oh, you were one of those students.

Maruyama:

(laughs) Yes. My transcript was, well, mixed. I like to think that it had the right mix of things where it looked like I had an upward trajectory going from rudimentary English to being able to speak the language fluently. Sciences were strong. I was also in a public school in Connecticut, at one of the better ones. I also had friends who were motivated to go to college. Motivated to get out of the town that we (laughs) grew up in. And so yes, I think being surrounded by these peers was helpful because my parents and I, we really didn't know the process of visiting schools, how to apply for colleges, these things.

Zierler:

Right.

Maruyama:

We didn't know, but I had friends who could...

Zierler:

Now, were you thinking specifically about physics programs? Did you know that that's what you wanted to pursue from the beginning?

Maruyama:

Physics was one of my majors I was thinking of. It wasn't a completely clear, obvious thing, but I really did love my physics class in high school. I had, again, a fantastic physics teacher in high school. And I knew I liked physics better than chemistry or biology or any of the other sciences. So yes, I did definitely put that down as one of my majors. Music, again, was also another interest of mine.

Zierler:

Why Columbia? How did Columbia win out for you?

Maruyama:

I didn’t know then, though in retrospect, I think it was the perfect place for me. I don't know how it goes, whether college shapes you or you...

Zierler:

Now, did you want to be in New York? I know kids that grow up near New York would go in on Saturday night and things like that. Was New York sort of exciting to you throughout high school in that way?

Maruyama:

Yes, definitely. It was definitely an exciting place to be. And--

Zierler:

Was it also an opportunity in New York to hang out with other people from Japan? Japanese people?

Maruyama:

That wasn't so much on my radar. We ended up moving to a town where there were basically no other Japanese people.

Zierler:

No but that's exactly what I'm asking. I assume you were in a very sort of white bread kind of Connecticut town, so was part of the attraction with New York... I mean, not Japanese people particularly, but just like... more diversity.

Maruyama:

I think more diversity, more vibrance. You know, an exciting new place to be. A great school, a great program. All of that combined was definitely part of the choice.

Zierler:

Applied physics is distinct from regular physics in what way, at Columbia?

Maruyama:

As an undergraduate student at Columbia, you might be at Columbia College, Barnard College, which is an all-women’s college, or the engineering school. I actually started at Columbia College and transferred into the engineering school, to be in applied physics. When I went to Columbia College, I did start out with the program of physics, with a major in physics in mind, and it turned out that in my year, there were very few people who wanted to study physics, maybe two other people. It was just a very small class. That combined with, I hadn't realized that at the time, but I actually really wanted to take more of the technical classes that the requirements of the major at the engineering school would allow me to actually take, like Fortran programming and (laughs).

Zierler:

So was the plan, did you want to become an engineer initially? Was academic physics not part of the original interests or pursuit for you?

Maruyama:

I didn't know, too much about whether I really wanted to be more of an experimental, technical physicist, as opposed to a fundamental physicist. I think I have the best of all now, but I was always interested in the experimental side of physics. The program at Applied Physics at the time had, and still has, a lot of electrical engineering, and we were looking at laser physics, and plasma physics was also a big component. But yes, the program itself and also the ability to actually have a cohort of, you know, fellow students in the major, was what really motivated me to make that switch.

Zierler:

How much of the curriculum was located in the main physics department? In other words, were you taking the same kinds of classes that physics majors were taking as well?

Maruyama:

Yes, some of it. They were offering parallel classes in quantum physics classes, electricity and magnetism, etc., and we could choose, I remember taking electronics lab and mechanics courses in the physics department. So, there were-- we could choose between the two.

Zierler:

Who were some of the professors that you became close with during your time as an undergraduate?

Maruyama:

Michael Moore, who does plasma physics. Irving Herman, Professor Chu. (laughs) It's been a while.

Zierler:

You can put it in the transcript when it's ready. (both laugh)

Maruyama:

And then the other really important part of undergrad education, I think, were summer research programs, so research experience for undergrad, REU programs, at different places. I spent a summer at Rochester and that had a really big impact on how I think about it.

Zierler:

In what way? What was so impactful about that?

Maruyama:

I think the fact that you're spending 8 or 10 weeks among a group of students who are all so interested in physics, so excited about physics, and you're really focusing on just doing something that is a little bit new or that nobody-- well, a lot of people may have looked up, it's kind of your own research project. You have a professor who is working with you and mentoring you through that process. I think those things combined, belonging to a community where you have a shared passion, plus having mentorship from a professor, I think those combined were really important for me to start thinking about physics as a career.

Zierler:

Reina, by the time you finished your undergraduate, how well-defined were your interests in terms of the kind of physics that you wanted to pursue in graduate school? Specifically, why did you transfer to a-- I don't know what the right word is, "regular," classical standard physics program? Why not continue in physics with an engineering perspective? What were you thinking on that?

Maruyama:

That's a good question. I think, what I realized is, what drives physics as a fundamental understanding of how things work, and for me that was a motivating factor in trying to really understand and seek out how just the fundamental laws of physics work. That's what was interesting to me.

Zierler:

And where did you apply for graduate school?

Maruyama:

(laughs) Everywhere.

Zierler:

Again everywhere.

Maruyama:

Again, yes.

Zierler:

Did anybody at Columbia encourage you to stay on board? Did you get any advice one way or the other in that regard?

Maruyama:

I did not. In Physics, we often advise our students to explore graduate programs different from where they were for undergraduate studies. Also, I was interested in programs strong in atomic physics, a field I became interested in after the summer at Rochester. The following year summer, I went to Los Alamos for a summer to do atomic physics.

Zierler:

Cool, Los Alamos.

Maruyama:

That was an amazing summer. And those--

Zierler:

Were you doing any national security stuff there, or you were on the other side of the fence?

Maruyama:

I was on the other side of the fence. (laughs) But I got a little taste. I was still not a U.S. citizen, so I had a red badge. One time while cycling along the road in Los Alamos, I was told to pull aside because they were transporting some nuclear waste material. But that was also an incredible summer in a similar way that I described before.

Zierler:

Now, were you thinking about specific people to work with for graduate programs?

Maruyama:

I don't think I was so directed. I see a lot of students coming in now, and they've figured everything out, which is really impressive. I didn't, no.

Zierler:

It's impressive, but it's also a little problematic too. I mean, you don't want to be overly focused as an undergraduate.

Maruyama:

True. I didn't even know to pretend. But I knew that Washington had a very good atomic physics program, and that was actually one of the key things from the summer REU program, was to get guidance from my mentor to say, "Well, these are the people you should look up." And so yes, the person I ended up working for was on that list as somebody I should be looking up. And I was actually waitlisted first round for my graduate school at Washington, but when I called and said, "I really, really want to be there." They said, "Yeah, we weren't sure you wanted to come here, so we put you on a waitlist. Yes, we would love for you to come!"

Zierler:

Yeah, Washington, I've talked to a lot of people at Washington, and there's that problem where, it's really a topflight school, but it's also the second choice for the Stanfords and the Berkeleys and the Caltechs and the MITs and places like that. Even though it's an incredible place all on its own. It's like a structural institutional problem that Washington has.

Maruyama:

Yeah.

Zierler:

Being in Seattle is a good thing too as well. I'm sure that was fun for you.

Maruyama:

Yeah, it was really great. I enjoyed it a lot. I stayed for seven and a half years in graduate school. (laughs)

Zierler:

Oh you did? You took your time. (both laugh)

Maruyama:

I took my time.

Zierler:

So how did you develop a research agenda and an advisor to work with? How did that play out for you?

Maruyama:

I can't remember it being so directed, but I do remember going to talk to Norval Fortson, who became my advisor.

Zierler:

I mean, minimally, you know you wanted to do experimentation. You were not interested in pursuing a theoretical degree.

Maruyama:

That is right.

Zierler:

All right. So that's one divide we can sort of cross off the table. You were at least directed in that regard?

Maruyama:

Exactly. And I knew I wanted to do smaller-scale experiments, where I would get to build things. I would have my hands in that. That meant either condensed matter or atomic physics. I talked to several professors to see if they had openings, if they were looking for students. So yes, I did explore around quite a bit, but in the end, I think, Norval had a position open, and I worked with him for a semester before we both decided to go ahead with it.

Zierler:

And what was his research? What was he working on at the time?

Maruyama:

He had an experiment to look for symmetry violations. Time reversal symmetry in mercury-199. It's still one of the most sensitive experiments to look for permanent electric dipole elements. He also had an experiment on thallium to look for parity violation. I started out with thallium. We had infrared lasers and green lasers that we were just implementing, and I built power supplies, power switches, and relays, and we were in the machine shop building this and that for the optical table. And I really liked building things.

Zierler:

Reina, I'm curious, coming from the engineering physics perspective, in terms of the coursework at Washington, did you feel like you needed to take more courses than the standard curriculum, just because it was in some ways a transition for you? Or was engineering physics in terms of what you wanted to do, was your undergraduate training enough, as far as you were concerned?

Maruyama:

It was okay. It was fairly seamless; I think the applied physics program was close enough to the regular curriculum that it was not such a big transition.

Zierler:

And so how much coursework was there at Washington? I mean was it labs all the time from the beginning, or there was an intensive period of coursework at the beginning?

Maruyama:

As in most physics programs, there were intensive courses in the beginning, three or four classes, maybe, for the first year. And teaching.

Zierler:

How did you go about developing your dissertation topic?

Maruyama:

This was in collaboration with my advisor. He had this time reversal symmetry idea, and during this time was the beginning of atom trapping and cold atoms, and we didn't really call it quantum science back then, but a lot of the things that were happening with--

Zierler:

I mean, we just have to state for the record how young the field is, because when you say, "we didn't," you're young, right? This is like really, very, very modern advances. So, in terms of cold atoms, just for a little historical background, what were some of the technological advances that made this field even become a reality?

Maruyama:

By the mid-90s, people were able to actually cool the atoms using lasers. Basically using light pressures to slow down beams of atoms, trap atoms, and hold atoms in a small space and volume for extended periods of time. Then going beyond that was accomplishing Bose–Einstein condensate, where you basically inform a single quantum stage using atoms. You put them all in the same condensate. With these kinds of things, it was really, really exciting at the time, and at the same time, there were a lot of optical communications that were being developed on the industry side. Lasers, atoms, optical communications, all this was really happening at the time. And also, the internet. I went to Seattle when Amazon was just starting, and my friends from college were coming to Seattle to pack books for some unknown company. (both laugh) They were like employee number 30-something. (laughs) There was a lot happening at the time. But anyway, on the atom side, once you can hold atoms that are very cold, not moving or moving very slowly, then you can start imagining doing more precise measurements. Spectroscopy on the atoms. Then things like looking for time violation, fundamental symmetries were things that people were really thinking to do, using these cold atoms.

Zierler:

Now, the phrase, "cold atoms," is that metaphorical, or does it really refer to lower temperatures of atoms?

Maruyama:

It really is lower temperatures. They're slowed down to Bose–Einstein condensate, which is basically absolute zero, where you have definition of temperature, is basically how fast the atoms are moving. And you can cool them down, like what I was looking at which was like microkelvins of atoms.

Zierler:

So allow me to ask a dumb question on behalf of the public, right? We associate lasers with being hot. How are lasers used to make atoms cold?

Maruyama:

Atoms have a very specific wavelength or color of light that they can absorb, and so you see this in streetlamps, where sodium absorbs this orangish color. Atoms have a very specific color. If you can get it so that, let's say they absorb photons that are a particular color, but shed photons at a lower energy systematically, then you can reduce the kinetic energy that atoms have -- Well, what you're trying to do is shed the kinetic energy of the atoms to the environment. Let’s say you have atoms coming in one direction, you shine a laser in the other direction, and because they're counter-propagating the frequency that the atoms see, it's a little bit higher than the lasers. So the atoms absorb a photon at a particular energy, and then they shed that energy in photons, more energy into photons than they absorbed. You've now given up some of the energy into the environment. And you do that many, many, many times and then you can cool the atoms.

Zierler:

So the follow-on dumb question is, why not just stick these things in the freezer? Why does that not work?

Maruyama:

You can do that to some degree. The coldest easy temperature to get to easily in a freezer is 4 kelvin, which is at liquid helium temperatures. You can use things like dilution refrigerators to go down to few milliKelvins. You can have a gas in some volume, and then what do you do? You have the atoms hit the walls and other atoms to thermalize, or if the freezing temperature of the atom is higher than 4 kelvin, they just stick to all of the walls. You need some other way to shed the energy into the environment.

Zierler:

Now, obviously, from a basic research perspective, this is interesting just because it gives new opportunities to understand atomic structure, right? But I wonder what right off the bat might be some of the commercial opportunities or commercial viabilities for being able to do this?

Maruyama:

That's what we're seeing with all of the quantum computing, quantum cryptography. Those kinds of things. They're used--

Zierler:

And this was obvious right from the beginning? Quantum computing? As soon as we're talking about lasers and cooling atoms, quantum computing, quantum information, that's sort of part of the calculation from the get-go?

Maruyama:

Yes. Once you have a state of atoms where you're starting to talk about quantum ensembles, then people were thinking about, "How do we use this for things like quantum..." We talked a lot about quantum cartography at the time. And more precise clocks.

Zierler:

And so what, as you were developing your dissertation, what were the major research questions you were asking, and how well were those directed towards the basic research, the basic science? And how much were they toward thinking, you know, how might this make things better in society?

Maruyama:

The research that I was doing was to see whether we can use this environment or this technique of cooling down atoms and holding these atoms to do precision measurements on ytterbium atoms, to be specific. With ytterbium, there is a possibility that we could look for time symmetry violation. In physics we talk a lot about physics that is governed by symmetry. Preservation of symmetry allows us to formulate forces in a way that constrains them. We have not seen evidence of charge, parity and time symmetry combined being broken.

Zierler:

To this day, you mean? We haven't seen this evidence?

Maruyama:

That's right. To this day. We have seen time symmetry being broken certain processes. In time-symmetric processes, if you were to play a movie of the fundamental physics process backwards, the process you observe would be allowed the laws of physics. If you were to play a movie of a process that violates time reversal symmetry backwards, you would be able to tell that it is playing backwards because that physical process does not happen in nature. There are few processes that break time symmetry, but in the processes where we have observed to break time symmetry, then parity and charge are also broken. So, CPT combined we haven't seen break. People are looking to see, is this a fundamental symmetry that in fact cannot be broken? Is there any way to break the symmetry?

Zierler:

Reina, what are some of the theoretical underpinnings that would force that question even to be asked?

Maruyama:

It's an extension to everything that we understand that we can formulate today. The so-called standard model of particle physics. We're doing experiments like what I was doing for my PhD program, to see if there are little breaks in the fundamental standard model that we have already formulated, and whether there is an extension to that. Things like dark matter, we cannot yet explain with the standard model of particle physics, and gravity doesn't quite fit in nicely in there either. Neutrinos have properties that are outside of the standard model.

Zierler:

You're listing all of the big mysteries in physics. This is everything right here. (laughs)

Maruyama:

And here I am. (both laugh)

Zierler:

Reina, what might be some of the technological or experimental breakthroughs that might allow evidence to become available? To be seen?

Maruyama:

I don't know if I can quantify, actually, what technological breakthrough we need. I think a lot of the experiments that are going on now are really pushing the boundaries of what is technologically possible. Like the axion search experiments trying to detect photons at 10-25 Watts level. Can we make our photon sensors more sensitive? Can we make magnetic fields bigger than 9 Tesla in a volume of 20 cm bore below 4 kelvin at a reasonable cost? So yeah, getting these things to work at cold temperatures, quiet environments, more sensitive measurements of electromagnetic waves, more sensitive measurements of photons, more sensitive measurements of… So the way we look for these extensions to new physics is to rely on theories where they would couple to forces or signal that we know how to measure. Can you somehow have dark matter interact with regular matter so that you end up with electrons, photons, sound, or heat. You turn the unknown into a known signal and you try to detect minuscule amounts of this signal. And we look for and develop ways that enhance the sensitivity of these instruments.

Zierler:

Reina, just to build a bridge from your research in graduate school to all this exciting stuff you're doing now. Are you asking the same questions now in a more nuanced way? Or as a result of advances in the field over the past 15 or so years, are you now asking different questions than what you were asking as a graduate student?

Maruyama:

I think the questions are still similar. We know our understanding of the physical world complete. How can we improve it?

Zierler:

That might be asked for some time to come, if that's as big as a question as you're asking. (laughs)

Maruyama:

We've learned a little bit in my short (laughs) life. In my long, long tenure as a physicist. There have been a couple of really, really big discoveries in the field. We learned that neutrinos have mass, that's a big deal. And that makes the search for neutrino-less double beta decay more compelling. Gravitational waves exist. I didn't have too much to do with that, but that's really exciting.

Zierler:

But we all watched as that was proved.

Maruyama:

Yes. These things are real, and they cannot be explained by what we call the "standard model" of particle physics, and so now how do we bridge what we see in the real world to the description of the world that we have today?

Zierler:

Now, there are many, many ideas about this and sometimes they approach the quasi-metaphysical, but at what point do you see improving the standard model as getting closer to a grand unified theory? And that of course is based on the assumption that you accept the premise of a grand unified theory.

Maruyama:

Short answer is that we don't know. There might not be a grand unified theory, but to me, this is what it means to be human, to try to push the boundaries of what we understand. Try to understand the world that we live in and to try to make sense of it. And I think people who play music, sports, or create art – anything to push the boundaries of human knowledge -- know this, but when you get it all together all at once and you make something new... it's a wonderful feeling.

Zierler:

Reina, I'm curious. You were in graduate school right smack in the middle of the tech revolution on the West coast, and given your research interests, and the impact of quantum information on the internet, on telecommunications, did you ever think about jumping ship from graduate school and academic life and sort of getting involved at the ground floor at any of these startups that were happening in Silicon Valley?

Maruyama:

I did. There were things happening in Seattle too, and some of my friends and colleagues went into industry. They didn't finish college, or dropped out of graduate school right then. I think for me, it was sometimes difficult to pursue a career in academia, but I always knew that there was a world outside that is also very exciting and interesting and all of that. But at the end of the day, what an incredible honor to be able to be thinking about dark matter (Zierler: That's right.) and what we are made of. These--

Zierler:

I mean the way that you talk about your curiosity, it's obvious to me why you stayed in academia. But I was just curious if that even crossed your mind, or if it was something that was available to you.

Maruyama:

Yeah. I did think about it. Sometimes a lot. But the life of an academia is good—for example, I've never had a boss, and this suits me just fine. (laughs)

Zierler:

From one PhD to another, I get it. I totally get it. How did your postdoc come together at Berkeley?

Maruyama:

This is a good story. I was finishing up my PhD, and around that time, My now husband, Karsten Heeger, was in graduate school with me. We had started at the same time. And he has--

Zierler:

In physics?

Maruyama:

In physics, yeah.

Zierler:

Oh, so you accepted the two-body problem?

Maruyama:

Yes. (both laugh) He spent a little under seven years in grad school, so he finished a little before me. When he was looking for a postdoc, we looked for places where there were also potential opportunities for me. He does neutrino physics, and at the time I was doing atomic physics. And we had looked up places like Los Alamos. And Berkeley. He ended up in Berkeley, and somewhere a month or two after he was there, I get this email from from an alumnus of the lab that I was in who was now at Berkeley saying, “Anybody finishing their PhD, would you like to come to Berkeley?” I ended up going to Berkeley to work on cold atoms, but now looking into Weak Interactions. Nuclear physics. We were trapping radioactive atoms right out of the cyclotron. That was fun. So it turns out that this lab, this group, was also the group that my husband went to. The PI, Stuart Freedman, his interests were broad enough that my husband and I ended up in the same group as postdocs.

Zierler:

What were your impressions of the instrumentation, coming from Washington to Berkeley? Was the lab, being that it was part of the DOE and there were probably more funding resources, did the instrumentation strike you as better immediately?

Maruyama:

The lab had different kinds of resources. I was at a cyclotron and there were equipment that were like, 40 year old instrumentation lying around, and you could rummage around and find new things to plug them into. I appreciated this. The laser and atomic physics part was actually very, very similar. So there was a familiarity to what I did. And then the availability of technical support and people, there were many people to talk to, to talk about technical things, to talk about physics. That was really, really exciting. I was also not allowed to do a lot of the things at Berkeley that I did by myself when I was a student in Seattle. There were technicians who serviced vacuum pumps and things like that, so also learning to get help from technical people who were there was a new experience for me.

Zierler:

Reina, what was the research environment like there? Did you essentially join a group where the agenda was pretty much set, and you plugged in? Or did you have opportunity to pursue your own interests? Including any ways that you might want to build on or refine your graduate research?

Maruyama:

A little bit of both. There was definitely enough of a defined program, but I had a little bit of a freedom in choosing what I wanted to do. I went there as a UC Berkeley Chancellor's Fellow, which is part of a University of California initiative to try to diversify their faculty. It was built as a pipeline for faculty. With a fellowship, there's some freedom to carve your own path and to choose what you want to do, and because it was not funded by a particular grant. With that, I worked on this radioactive atom trapping experiment, and then after I did that for a while, I worked on CUORE experiment to look for neutrinoless double beta decay. The opportunity to work on that came up, and I felt that was a very, very good project to look into. That's how I got involved in neutrino physics.

Zierler:

Did you do a lot of writing during this time? Were you going to conferences and presenting?

Maruyama:

Some. Toward the end of my postdoc, we were trying to get the CUORE experiment funded, so I learned about project management and writing proposals for the larger experiments, and from all of this I got a good taste in projects managed by the Department of Energy. I also wrote proposals to compete for – and won -- lab internal funding to start a new accelerator project.

Zierler:

And I assume heading next to Wisconsin, to the IceCube Center, that must have been as a result of your work in neutrino physics?

Maruyama:

That was. It was largely that, but also the two-body problem, as you called it.

Zierler:

Right. (laughs)

Maruyama:

My husband Karsten and I got married while we were postdocs. He got a job at Wisconsin.

Zierler:

And this is a faculty position that he got?

Maruyama:

Yes, he got a faculty position, and you asked earlier about whether I considered other options, and yes, at this point I wasn't quite ready to pursue a faculty position. There are lots of interesting things to do outside of academia, and I was exploring other options as well. When the opportunity for him came up to take on the faculty position at UW-Madison, I found the opportunity to work on the IceCube Neutrino Telescope as a research scientist very attractive. The IceCube Collaboration was a much larger collaboration than anything I was used, and much more established. A different kind of way of working. It was also hard to turn down an opportunity to go to the South Pole to look for extragalactic neutrinos.

Zierler:

Oh, did you go? You went to the South Pole?

Maruyama:

Yes. (laughs)

Zierler:

Oh wow, what year was that? When did you go?

Maruyama:

I went twice. First time during the 2009-2010 season, and then the second time during the 2010-2011 season.

Zierler:

What was that like? When you were there? First of all, how did you get there? Was it a ferry from Argentina?

Maruyama:

No. We flew to New Zealand, and...

Zierler:

New Zealand. Why New Zealand? Was that because where in Antarctica you're going to be? That's the smartest place to go from?

Maruyama:

It's the U.S. military base kind of connection. That's how the U.S. Antarctic program is operated. So, we go to New Zealand, and then from there you take a U.S. Air Force Reserve airplane to the outer shore of Antarctica to McMurdo Station. That's the biggest U.S. base on Antarctica, and it serves as the starting ground for a lot of research that is going on all across Antarctica. From McMurdo, you take another airplane to the South Pole.

Zierler:

Did you get any advice on how to pack for this trip?

Maruyama:

(laughs) Yeah, IceCube is a big enough collaboration that a lot of people around me had already gone, so I got advice on what to pack, how to survive with only being able to shower twice a week, how to get things done, that sort of thing. The biggest thing is that the South Pole is at 10,000 feet altitude, so you want to be careful about altitude sickness. A lot of advice was based on that.

Zierler:

And so, what's a day-to-day look like? How does actually being physically present in Antarctica advance neutrino physics?

Maruyama:

With IceCube, you're using the volume of the ice itself as the detector. As high energy neutrinos come in from the atmosphere, mostly, but stars when they explode produce neutrinos too. So they come into the ice and interact with the molecules of the ice. After neutrinos interact with the ice molecules, they are converted into relativistic electrons or muons. The electrons and muons emit what’s called Cherenkov light as they travel through the ice. We instrument the ice with many, many light sensors and by looking at which sensors saw light and amount of light detected, we reconstruct the energy and direction of where these neutrinos came from.

Zierler:

Reina, did you see your work in neutrino physics as a departure from what you were doing before? Or was it complementary in a broader sense?

Maruyama:

Yes. In all my previous experiments, I was looking for processes where the particles I was studying were created in the lab. IceCube looks for neutrinos coming from astrophysical events, like from the Sun, or gamma ray bursts or supernovae. IceCube is a big enough instrument that it can also measure fundamental properties of neutrinos. I think that was a big departure. The fact that we were just looking for neutrinos appearing from exploding stars. That, and working with hundreds of other people. There were engineers and a very well laid-out project management. I learned a lot of different aspects of what it means to be doing big science.

Zierler:

I wonder if your engineering physics background came in handy during this time.

Maruyama:

Perhaps.

Zierler:

Did you think about, did you want to stay in neutrino physics? Was that something that you seriously considered?

Maruyama:

I very much enjoy the fundamental aspects of what I do. I love the experimental work that I am doing now to search for neutrinoless double beta decay. I'm still a member of the IceCube collaboration, and I am currently focusing more on the fundamental properties of neutrinos trying to understand the nature of neutrinos themselves as opposed to them as messengers of other events.

Zierler:

Now, I wonder Reina, before you actually joined the physics faculty, how well-connected were you with the physics faculty just as being a scientist with IceCube?

Maruyama:

That definitely helped. The advice that you often hear that being a research scientist is actually pretty difficult to turn the position into faculty positions. People at the University of Wisconsin in Madison were very supportive of my career, and what I wanted to do. When I decided that I wanted to become faculty, when I was ready to do so, it wasn't straightforward, but it was possible. I knew a lot of people there already, and on the faculty, as well as research scientists.

Zierler:

So, when you joined the faculty, did you continue to focus on neutrinos, or this was an opportunity for you to go back to some of the stuff you were working on before?

Maruyama:

What happened in that interim is I got into dark matter physics.

Zierler:

Ah. That's when that happened.

Maruyama:

Yeah.

Zierler:

What was the initial interest that caused you to get into dark matter?

Maruyama:

In Wisconsin I was continuing to work on the CUORE experiment, the neutrinoless double beta experiment that I had been involved as a postdoc. In the dark matter world, there is this one experiment called (DAMA 1:05:18) who was claiming to have observed dark matter in their experiment. This is an anomaly. Their result is contradictory with many of the other non-detections of dark matter from other experiments. So, the dark matter community -- people from the dark matter community actually came to the IceCube collaboration and asked if we would look into this problem. The signature that the DAMA collaboration observed is an annual modulation in their signal. And you expect-- Should I explain? I should explain.

Zierler:

Absolutely. Absolutely.

Maruyama:

The picture of the world we have of our galaxy is that when our galaxy formed, we ended up with the Milky Way as we know it, and then this Milky Way is surrounded by a halo of dark matter. And as our sun is rotating along with the galaxy and the Earth is rotating around the sun, we're going basically through this cloud of dark matter, and--

Zierler:

So, we know we're going through the cloud of dark matter without really knowing what dark matter is.

Maruyama:

Exactly. From observations of how the galaxy rotates, how stars within our galaxy rotate, we know there is more mass than we can see. And we call this extra mass dark matter. If dark matter is a particular kind of substance, we're calling it WIMPS, Weakly Interacting Massive Particles. Then it's possible that as we go through this cloud of dark matter, some of the WIMPs could collide with detectors on the Earth and create a little signature that we can detect.

Zierler:

How much at this point were you starting to get involved with astrophysics and cosmology? I mean did you feel like you needed to read up on these things, or your background you could just sort of jump right in?

Maruyama:

I jumped in mostly from the detector side. A lot of the detectors that are used in these WIMP searches are basically the same as what I was using for the neutrinoless double beta decay experiment. These two types of experiments use different energy ranges, but basically, it's something that I knew. The physics part I knew generally what it was about, but yes, I did have to learn some new things. The signature that DAMA collaboration saw is an annual modulation produced as the Earth goes around the sun. In June the Earth and the sun are going in the same direction through the cloud of dark matter, and we expect to going through the cloud dark matter at a slightly faster speed. Then in December, the velocities are opposite, so you expect to see slower dark matter and less collisions of dark matter with your detector. DAMA sees this annual modulation very clearly, and a lot of people suspect maybe the signal is due some sort of seasonal variation in something, that we don't exactly know what yet. People trying to understand what could cause the signal DAMA was seeing thought that the South Pole environment would be a really great place to try to chip away at this mystery of why this one experiment is seeing dark matter signals, whereas the other experiments were not. And so, we--

Zierler:

Has that mystery since been solved?

Maruyama:

I'm still working on it. (laughs)

Zierler:

Okay.

Maruyama:

That brings us to the current research. The dark matter community wanted to know if we could do this experiment at the South Pole, which happens to bring together my CUORE experiment expertise, with the IceCube expertise, and then a new experiment was born.

Zierler:

Reina, when you got tenure at Wisconsin, was your sense that that was in recognition for any particular body of work that you were involved in, or it was more recognition of the culmination of your contributions up to that point?

Maruyama:

That's a good question. I would say I'm probably known best for this dark matter experiment to teset DAMA. We called it DM-Ice. But this couldn't have happened without all of the other components of my experience. So, I’d like to think that my tenure is a recognition of this body of work.

Zierler:

There are several possible history-making moments when you got tenure at Wisconsin in terms of firsts. Are you aware of any firsts that you might have made as a result of becoming a tenured professor at Wisconsin?

Maruyama:

Not that I know of.

Zierler:

I mean in terms of Asian-American-- Certainly there were women who were tenured professors in physics before you. I assume.

Maruyama:

I see. We have Sau Lan Wu at Wisconsin. She was a very big force, and still is a big force at Wisconsin. I was a first of... First of Reina. (laughs)

Zierler:

Would you say generally, Wisconsin was good in terms of diversity and inclusivity and those kinds of things?

Maruyama:

For me, it was a very good place.

Zierler:

You can only speak for your own experience, of course.

Maruyama:

Yes. I do know some people who were not treated right. As an institution, though, they're really trying to do the right thing. And for many institutions, I think it's a difficult problem. As is the case for most department, there are aspects that are very inclusive, and others not so much. Nothing is black and white.

Zierler:

Did you think at a certain point that this is where you would make the rest of your career?

Maruyama:

I did really like it there. And that's where I felt very much supported. IceCube had its big center there, and that was really great. There's a lot of technical support. I could see myself there.

Zierler:

Did you take on graduate students at Wisconsin?

Maruyama:

I had four or five graduate students.

Zierler:

And how did the opportunity at Yale come about?

Maruyama:

This is a long story, but one of the big things, I think, was when I was applying for grants, I wanted to get feedback on my proposals. I had sought feedback on my proposals before I submitted them from several professors at Yale. When I got my NSF CAREER grant, I wrote to thank them for their help. Of course, I don’t know for sure this was a part of what brought the physics department at Yale to consider hiring my husband and I at Yale, but this kind of exchange we had with people at Yale, perhaps had something to do with it.

Zierler:

This was a bit of a gamble, though, because you were looking at giving up tenure for an untenured position.

Maruyama:

It was definitely a gamble. I knew I could do it because I had gotten a tenure once, and I knew I had a good program of research.

Zierler:

Maybe you didn't have a first in the sense of, you know, in terms of who you were getting tenure at Wisconsin, maybe this was a first in terms of giving up tenure to go back to an assistant professor line. I've not heard of many people who have attempted this before.

Maruyama:

Yeah, it happens, but that's what it was.

Zierler:

This of course begs the question, what was so compelling about Yale? I mean, besides-- I assume your family, were your parents still in Connecticut at this point?

Maruyama:

Yes.

Zierler:

So that's obviously a big draw, but in terms of the research at Yale, what was so compelling in that regard?

Maruyama:

This was definitely a big gamble. It was the sum of things. For me, the opportunity to really build on what I was doing appealed to me. I felt that Yale could support it too. Karsten also was thinking about his career. One of the things that we wanted to do at Yale was to actually transform what is now Wright Laboratory. It used to be Wright Nuclear Structure Laboratory. There was an accelerator here.

Zierler:

I learned all about that from Rick Casten.

Maruyama:

(laughs) Right. The series of physics that were being investigated in Wright lab had kind of run its course, and this big, gigantic space was available for us to transform it into a new laboratory.

Zierler:

Something totally new, I mean dismantle WNSL entirely, right?

Maruyama:

Exactly. And transform it into a space where we could explore physics, use it for dark matter research, neutrino research. Building onto what was already existing at Yale with Bonnie Flemmings' program for accelerator-based neutrinos. There was also a good atomic physics program. So, there was a good cohort of research that was being done here.

Zierler:

And so, part of the package for you was, we're dismantling this laboratory, blank slate, you can build what you want. That was really part of the offer?

Maruyama:

Yes, that was a big part of the offer.

Zierler:

And how much institutional support came with this offer? Was the expectation that you would come with your own funding, or did they say, "We'll help you get the lab up and running"?

Maruyama:

They really came through. Yale came through to rebuild the lab as a new facility. That was exciting. I mean, it was primarily Karsten and his hard work to get this done, and as an assistant professor, I got to focus on my own research. Another component of this move was actually, I was very much inspired by what one could at a place like Yale. Meg Urry was the chair at the time, and as a Yale professor, she really had a voice in how people viewed science. She was writing for CNN Science, and I think I found that kind of connection to the outside world, really inspiring, and I wanted to be a part of that.

Zierler:

And she was the first woman to be tenured at Yale. All the way back in 2001, I believe.

Maruyama:

(laughs) That's right.

Zierler:

Which is an amazingly recent past for that kind of a milestone. So Reina, did you have any experience sort of building a lab out of nothing before? I mean, you joined many experiments, but was this a completely new endeavor for you in 2013?

Maruyama:

Yeah, that was an entirely new thing. I had renovated the lab at Wisconsin a little bit to what I wanted it to be. It's a powerful thing to be with a partner when you're pushing for the same thing, in the same direction.

Zierler:

Friendly competitors, too, in some regards, I'm sure. (both laugh)

Maruyama:

Yes.

Zierler:

In having this amazing opportunity, what were some of the big questions, research questions, that you were specifically thinking about that might have served as an intellectual underpinning, when you were thinking about literally the nuts and bolts of instrumentation, of workspace, these kinds of things. What were those basic questions at the heart of this endeavor?

Maruyama:

At the core, there’s always this question of, what else is out there or how can we reconcile this incomplete understanding of physics where on one hand, we're talking about the standard model of particle physics, but then that doesn't actually describe a lot of things that we see in dark matter and neutrinos. There are properties that we don't understand. As we learn more and more about what we don't understand, we might need larger facilities. We need more sensitive experiments instrumentation. Space to build instrumentation, but also where the space is conducive to collaborative work. We really thought a lot about how to make it a more open space, where people want to be at and where people want to work together. Where people want to contribute to the work, and how to make it easy for people to explore new ideas and start new experiments. These are the things that we thought about as we built the lab.

Zierler:

Now, your answer throughout has been, you know, "I'm still working on this," right? These are still experiments, of course, that are still underway. Is there anything over the past five, six, seven years where you can look at what's happened in the lab and said, in a concrete way, we've really pushed the ball forward in this particular area?

Maruyama:

Let’s see...

Zierler:

Maybe that's such a bit of an unfair question, given the magnitude of the questions that you're asking, but even in an incremental sense, what advances can you point to in the recent past?

Maruyama:

With the dark matter experiment, we built a whole new experiment and this experiment can answer the question of whether DAMA saw dark matter or not. We need to run it a little bit longer, but I think we can answer soon.

Zierler:

Ooh. Stay tuned for that. That sounds exciting.

Maruyama:

We've measured nothing more and more precisely (laughs), you know, so we know that neutrinoless double beta decay, that hasn’t happened. I think we're extending our understanding, but we haven't measured, or we haven't observed these effects just yet. We also have a new experiment on axions to try to look for them.

Zierler:

What is the research environment like there? I mean is this a place where you have postdocs, graduate students, senior people who are on a visiting basis, is it all of the above in terms of who's doing the work there?

Maruyama:

At Wright Lab, we have 13 faculty who have some sort of activity, and postdocs, research scientists, graduate students, undergraduate students. Technical people. We have a machine shop, we have a clean room, we have laser cutters, we have water jet machine shops, we have a few experiments actually running at the laboratory to look for axions, to look for microgravity. There are many people coming from all sorts of backgrounds there.

Zierler:

And who have been some of your most productive collaborators in the lab over the years?

Maruyama:

I collaborate with another faculty on this axion search experiment, Steve Lamoreaux. That's been a really, really great collaboration. We are all working together to educate our students and build new experiments. That sort of thing. It's a collaborative environment.

Zierler:

And in what ways is the research going on at the lab complementary to research going on at other labs, and in what ways is the research truly unique, and it's really a place unlike any other?

Maruyama:

What makes Wright Lab unlike any other I would say is the space. There are very few universities where you can have this space and technical capability to enable testing new ideas on a quick timescale. When I had the idea to try to extend the mass range of axions searches, I was able to basically bring in an instrument, plug it in, and do a little tweaking, but there was the ability to do that. There were a few other ideas that our two new faculty brought with them. One is looking at cosmic microwave backgrounds and 21cm radio signals from early universe and the other is doing gravity research at short distances. Enabling these new, exciting ideas in a university setting where we can take a little bit of risk and do things on a fairly quick timescale is pretty unique.

Zierler:

Are there opportunities for collaboration with other major ongoing experiments, like all the things that are going on at NASA or LIGO for example?

Maruyama:

Yeah, for sure. This really depends on what the PIs want to do.

Zierler:

Can you talk a little bit about your affiliation with the Quantum Institute? Is this sort of a separate hat that you wear, or is it all sort of combined into one overall research framework?

Maruyama:

This primarily comes because of this new axion search experiment, so I'm really borrowing the techniques that are being developed for quantum information to try to detect photons for axion search.

Zierler:

And what's the connection there? How is quantum information useful in this regard?

Maruyama:

The researchers at the quantum institute are also trying to detect photons at high fidelity with low error rate. We're basically taking their devices and adapting them to use in a high magnetic field environment, and in a tunable frequency range. We're taking the techniques that they're developing for quantum computing, where there are different focus and different goals. And in turn, I think they see different applications of the devices that they developed, and we're pushing them, their technologies, to be able to do things at much broader frequencies. I like to think that it's a mutual relationship, but I’m not sure they feel the same. (laughs)

Zierler:

So, Reina, just to bring the narrative up to the present, even with the challenges of coronavirus and managing a lab remotely, what are some of the projects that you're working on up to the present day?

Maruyama:

I'm still working on the neutrinoless double beta decay experiment. We've actually built the experiment that I proposed when I was a postdoc. It's running and it's been taking data. That experiment is in a very remote spot in Italy.

Zierler:

That must have been so tremendously satisfying, to see this through all the way from what you proposed, you know, many years ago at this point.

Maruyama:

That's right. And we're thinking about the next version. Then there is an experiment at the South Pole. The detector is still running and taking data, but we've built a newer version. It is running in South Korea, with new collaborators in South Korea. The idea behind the experiment is the same - to test DAMA. So that is coming to fruition as well. And then an axions search experiment called HAYSTAC. This one is local, operating at Yale. And as I mentioned, it is using quantum technology to detect photons that would appear if dark matter were axions. We need to extend the photon frequency range that we can detect now to be able to search for higher-mass axions. This brings me back full circle to my PhD training as an atomic physicist to try to again borrow the development in atomic physics, this time in Rydberg atoms, to try to detect photons for axion searches.

Zierler:

Well Reina, now that we've gotten right up to the present day, I want to ask a few sort of broadly retrospective questions for the last part of our interview, and some forward-looking questions. So the first is, to go back to the first thing we talked about in terms of your work on the service side with women in faculty issues at Yale, what opportunities do you see now, particularly that STEM is in a period of self-reflection and reckoning, you know with #ShutDownSTEM and Particles for Justice and things like that. What opportunities do you specifically see now that might help just improve the culture generally in science? And what is your approach in terms of, you know, some people, their style is, they just do the science and you lead by example. And other people are sort of more out front on the issues, you know, either with social media or speaking in faculty meetings and things like that. So just generally, I'd like to get your sense on those issues.

Maruyama:

It's interesting to hear you talk about us being kind of at a juncture. I think since maybe because I'm right in the middle of it, I hadn't thought of it that way, but I think you're right. It's possible that we have a critical mass of younger people coming up. Not willing to stand by and watch people being hurt, really.

Zierler:

I should clarify. By "critical juncture" what I mean of course is that for underrepresented groups in science, it's not a critical juncture, it's the fact that it's been like this, it's still like this, and if we don't change, it's going to continue being like this. To clarify what I mean is, sort of communally or culturally, there's a self-reckoning beyond what underrepresented groups have always felt. That's what I mean by "critical juncture." Whether it stands, and whether actually good, positive things happen as a result, that of course remains to be seen.

Maruyama:

I really hope so. And I think we can really use this moment as a springboard, I hope, to try to push for change. Physics is a field that is and has been dominated by white men, but I think what is coming across now is that it's not just physics, it's the entire society and culture, so hopefully that gives people a way to say, okay, we can do better. We as a community can do better. I think it has to come from many different sides, and I hope we have enough diversity in physics or in STEM fields in general to try to push for this change. We need numbers. We need to educate more people, we need to keep people in the field, we need to make the place more inclusive. All of that takes a lot of sustained work.

Zierler:

Do you specifically see opportunity as a teacher to undergraduates to advance those interests?

Maruyama:

We need to do a lot of work to mentor, to train, to keep people who decide they really want to study physics. All too often students are discouraged and disappointed by lack of role models or how they are treated. It’s often very difficult for women and students of color to see themselves as future physicists. What I want to do is train students, to nurture them as scientists, and have them become as strong as possible so that they can go out into the world and continue to do science. Then institutionally, there's a lot of work to do. This is why I decided to chair the Women Faculty Forum, to continue to push change for the better.

Zierler:

Well, good luck in that regard, because it's obvious that there is a lot of work to be done, and the more people who simply recognize that there's a lot of work to be done, the better the chances are of success in these regards.

Maruyama:

Thank you.

Zierler:

Reina, I want to ask on the happier side, you know, back to the science, obviously you don't have 40 or 50 years in the field yet to reflect back on, but I wonder in your remarkably productive and relatively short career so far, can you reflect on some things in physics that were not really well-understood from your time as an undergraduate even, that significant advances have been made where there's a sense, we really have a good handle on that? Obviously, the other answer, the flipside of that is much easier to answer. You know, dark matter was a mystery. Then and it's a mystery now. But I am curious, either in terms of your own research in terms of the kinds of physics that you do as a representative of the field, what are some areas where knowledge and discovery have really been advanced significantly over the course of your career?

Maruyama:

I would say two things. One is the advances in cold atoms technology. The laser physics has advanced to the point where, years ago I was in the lab fiddling for hours to try to get my lasers to behave, and now I can just turn a key to get that going and keep it going for hours and hours and hours. That's incredible. Our understanding of neutrinos, I think, has advanced quite a bit. The fact that they oscillate, that they have mass. I think that's incredible.

Zierler:

Now looking ahead, Reina, for my last question, I'm always struck by physicists who come from remarkably different backgrounds all come to dark matter, you know? I mean it's really amazing, no matter what kind of physics, most people say the same thing, in terms of that forward-looking question. "I want to know what dark matter is. I want to figure it out." Right? How, for you, because the discovery and exploration of what dark matter is, how do you see-- and it's clear that when it's discovered, and hopefully it will be discovered, it is going to be a multi-disciplinary or an interdisciplinary collaboration that gets there. So, what do you see long term in terms of your expertise, in terms of your lab work, in terms of the way that you go about interfacing with instrumentation, what do you see as your contribution to that bigger effort that hopefully will happen, you know, in our lifetime?

Maruyama:

That's a good question. Hopefully I will contribute to our understanding of what it is. It's very possible that it's not just one form, that dark matter consists of many different forms, and it's not just one thing that we're looking at. But I would love it if I'm part of that discovery. I would like to develop better and more innovative instrumentation. We test and rule out ideas that don’t work. We educate and empower more people who might have amazing ideas, new ideas, who are willing to try them out.

Zierler:

Do you think it will be so cut-and-dry in terms of who finds it and who doesn't? Or is it going to be more of a, like putting a puzzle together. It's an incremental process and there's a lot of people at the table?

Maruyama:

Yeah, it might be like somebody sees something, and then there'll be a lot of follow-up to try to verify that, right? So, it'll be like a building up of evidence to have a more, fuller understanding. It could be that we don't recognize it right at that moment of discovery, but have follow-up evidence that confirms and builds on that. And that's what's going to give us the answer.

Zierler:

And to just push that forward a little bit, in terms of somebody might see something, right? As an experimentalist, and as somebody who works in the lab, you could be that person, right? I mean you could be humble and not say it, but I can certainly say it. So what, just give me a sense of what is it that might be seen? What could you see that could then snowball into, "We got it. Dark matter."

Maruyama:

Let's take the example of the axions. This would be light that appears inside of our apparatus. This should appear only when the magnetic field is on, right? Then let's say we see something at a very particular frequency, and we do everything we can to try to make it go away, or have it appear or not. Everything that we do has to be consistent with the of understanding of the model of the dark matter that we have. Let's say, for axions, if you turn off the magnetic field, it should disappear. If it stays on with the magnet off, then we test to see if it appears when we shield the experiment or we do the same thing elsewhere. And then you start mapping it out more and more precisely. If you have the capability to map out the frequency, then you can see if you can look at the spectrum, does it look like what you would expect from the dark matter velocity distribution that you would expect on our Earth? And so on. Once you see something that looks like a signal, it is our responsibility as scientists to study it as much our detector, resources, and technology allows to verify the signal. It is the responsibility of the community to also scrutinize and verify the result in a productive way. So, it's these series of verifications that must be carried out. Once we know what to look for, like what mass or signal strength, it will be much easier to do the verification than when we are looking in the dark.

Zierler:

Well, Reina, it's been an absolute pleasure speaking with you today, and I can't help but think, you know, what's going to happen first in terms of these dual goals that you have taken on? Is STEM going to become a more inclusive place to your satisfaction, or is dark matter going to be understood to your satisfaction? And for the sake of everybody, I hope they happen soon and I hope they happen at the same time. So, I want to thank you so much for our time together today, and it's been a pleasure.

Maruyama:

Thank you.

[End]