A Look at Women Pushing the Limits of Quantum Frontiers: Yiwen Chu

After completing her undergraduate studies at MIT, Yiwen moved down the street, to Harvard. There, she did her Ph.D. studying quantum optics with nitrogen-vacancy centers in the group of Prof. Mikhail Lukin. Wanting to try out a different quantum system, she worked on circuit QED as a postdoc in the group of Prof. Rob Schoelkopf at Yale. Through collaborations with the group of Prof. Peter Rakich (also at Yale), Yiwen also added quantum acoustics and optomechanics to her repertoire. In 2020, Yiwen was awarded the Sackler Prize in Physics.
When she’s not busy running the lab or teaching, Yiwen enjoys rock climbing. Even though there’s not always enough time in the day, Yiwen has been known to improvise and still get in those climbing sessions when she can (even if it’s at the lab itself).

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Initially, what attracted you to physics? Can you tell us a little about what compelled you to choose physics as a career?

I was pretty young when I became interested in it. I think it was in high school after taking my first physics classes. It was interesting to me and it fed into a lot of things that I was curious about. I thought it was really cool that physics explained stuff that you experience and can actually see. And part of it was also that when I was doing physics or science in general, it felt like something I was good at. I was a pretty shy kid, so whenI understood these really interesting concepts, it helped me feel more confident about myself. It’s a really good feeling. I’ve been sort of chasing this feeling through the rest of my career, basically.

What was your experience when you were pursuing physics in college, and did you have any doubts?

I majored in physics and math at MIT. I definitely had doubts starting out. You start out being one of the best students in your class in high school, but then so is everyone else going into MIT. And initially, it was a very difficult transition for me. I was friends with people in my class, studying physics, who were right away doing super well in their classes. They were super good at solving problems. And in the beginning, I thought ‘Why would I even bother doing this when there are people who are so much better than me?’

It took me a while to realize it wasn’t just how good you are at solving homework problems that makes you a good physicist.

So once I realized that I thought okay, maybe I can do this.

How did you reach the understanding that you were capable of being a good physicist?

I think once I started doing research. We were really encouraged to get involved in labs, even from the first summer. So I was doing research in different research groups in different fields. Fortunately, that was something I found really interesting and exciting, especially experimental work. And I realized that some of my friends who were really good at problem-solving when it came to homework and assignments, actually had a harder time transitioning to research. They found it frustrating that you didn’t have a well-defined problem to solve. When it comes to research, though, figuring out the problem is more than half of the battle. I also found that doing research, especially in experimental physics, requires so many different skills. For instance, being able to talk to people and discuss things, being okay with the fact that maybe the problems aren’t so well defined, and exploring that by asking the right questions. It’s so much more than just what you learned in physics class.

As you were going through this path, were there any role models or mentors who had a significant impact on you?

Absolutely! Once I started my doing research in my undergrad, I worked at a bunch of different groups. Even though I knew I wanted to do physics, I wasn’t sure exactly which subfield, so I tried out a different lab every year of my undergrad. It wasn’t until my senior year when I was working in the Atoms and Photons Group at MIT that I figured out this was the subfield I wanted to go into. The group was led by Professor Vladan Vuletić, and he was an amazing mentor. I really liked the day-to-day work that you do in this particular field. That’s why I’m still in it now. I also really enjoyed the atmosphere of the group. I saw an example of a group where people got together and had discussions and were all really passionate. And the discussions were very intense, but not aggressive in a way that was intimidating. So I felt like I could participate too. Vladan himself was also such a great mentor and was able to explain concepts to people at different levels. I was an undergrad and had only just taken quantum mechanics, but he was really patient and took the time to explain things to me.

Moving on to what you’re doing today, what is your current research focus? And what does a typical workday look like for you?

Our research group focuses on interfacing different types of quantum systems. There are people working on all kinds of quantum systems like circuits, atoms, optics, etc., and we are trying to combine them. I’m really interested in how all these distinct platforms can talk to each other. It’s a complicated process and usually causes not-so-desirable effects. So how do we control that interaction so that they can do something useful? Right now, we are focusing on combining, for example, superconducting circuits, mechanical resonators, and infrared light and trying to incorporate the capabilities of one of these platforms into the others or multiple together to do things. One of our current projects is transducing quantum information between different types of quantum systems, like from microwave circuits, into infrared light, which is a really big unsolved problem in the field right now.

As for a typical workday, that’s changed a lot over the last three years since I’ve started my group. When I first started, it was a lot of lab setup, like ordering equipment, assembling stuff, installing equipment, and overseeing construction. Now, I have a group of students who are also working in the lab. So my day consists more of discussing results, brainstorming ideas for what to do next, planning, etc. This is the third year that I’m in this position. I’m also taking on some new responsibilities, including learning more about the community here at ETH, understanding what everyone else is doing, and organizing things on various committees. So I’m trying to balance between finding the time to actually sit down and do physics and talk to students versus learning about the wider community at ETH.

Since you’re new to this role and still exploring the different responsibilities, what would you say is your favorite aspect of your work right now?

In the beginning, the thing that really struck me was that I get to work with people who all have the same vision as me and are interested in exploring the same topics. I like getting into the nuts and bolts, the fundamental details of the experiments. Before, as a Ph.D. student or postdoc, I would work on a single project and spend a lot of time and work on the details. I didn’t really have time to think beyond that specific project I was working on. I really enjoy that now there are various projects happening in my group and I get to discuss the really interesting parts and switch between different ideas, topics, and projects throughout the course of the day. Sometimes it’s a little hectic to switch gears and remember exactly which project everyone is working on, but I really like the fact that there’s always something different to think about and discuss.

What are your thoughts on some of the challenges faced by women working in quantum computing /physics today? And have you personally felt any bias?

I feel like compared to some other fields of physics, there are fewer women in this field. That in itself is a challenge. During my Ph.D., there were a few years when I was the only woman in a really big group of 15 to 20 people.

So regardless of what anyone else does, or what happens, you feel like you are the representation of your gender in this group of people.

And then, since this is a challenging field, there are often these really intense discussions about what’s happening, who’s right, who’s wrong, and trying to figure stuff out. So on top of the actual challenging topic, you also have that extra pressure of being the only woman present. I’ve experienced discussions where people were quite aggressive. It felt like we could have reached the same conclusions in a friendlier manner. As I said, I was pretty shy. So it took a long time for me to have the confidence to speak up and get over this extra pressure.

It also took me a while to realize that during a Ph.D., you’re only interacting with a limited group of people: the people in your research group. So you don’t really know if this is just the way it works for researchers everywhere or if there are different ways of working together. By the end of my Ph.D., I was really pondering that and how, if I went on to run my own group, I could foster a welcoming atmosphere that encourages discussions, so that everyone feels comfortable contributing. What really helped with that was going to a different subfield for my postdoc. Experiencing a different environment really helped me with building a friendly, positive atmosphere within my own group.

You’ve already touched on experiencing ‘imposter syndrome’ early on in your physics career. Have you had any other experiences with that and what advice would you give to your students feeling that way?

Right, when I first started at MIT that was definitely a huge hit of imposter syndrome. And every time you start a new role, you kind of feel like that. When I became a professor, I realized there will be so many new things that I’ll have to do, and I won’t know if I’m good at them until I do them. And if I had a student who feels like the work is really challenging, that maybe they’re not cut out for it, I would tell them that maybe your idea of the required skills and what you must be good at might not necessarily be accurate. The story is a bit more complicated than that, so stick with it.

Maybe you’ll see that you have a special talent or skill or something that you’re good at that people don’t emphasize so much, but is actually really useful in what it is that you want to do. You won’t find out unless you stick with it.

What do you think we can do as members of the quantum computing ecosystem to inspire and encourage the next generation of women in science and engineering?

One thing that’s really important to me as a professor is establishing a culture and atmosphere where people feel like they can openly talk about the challenges they’re facing. And it is even more important that the students and individuals in the group themselves contribute to this culture.

In physics, a lot of times people think they need to not show weakness and act like everything is always under control. While in reality everyone is kind of struggling with different things, whether it’s the scientific side, or more general.

Earlier I mentioned feeling like you don’t belong. That’s not specific only to women, it relates to everyone. So establishing that it’s okay to talk about these feelings is important. Also as a PI, it’s important to show that you care about the personal aspect too, and not just how the experiment is going. So I try to have a conversation with each of my students every half a year where we don’t talk about anything science. We focus on questions like, How are you getting along with other people in the group? How do you feel about your progress? Are you happy here? And I think that helps a lot.

It also comes back to the fact that it’s not just how good you are at solving physics problems. There are so many other skills and attributes that are important to being a researcher. For me, it was helpful when people were open about that and were willing to share things that they were worried about, and challenges that they were facing. So having that type of culture where it’s okay to admit that you’re struggling or need help, I think is a culture that could benefit everyone.