Meet Giulia Semeghini

Giulia Semeghini's academic path took a winding course. While she contemplated studying journalism and law, it was the allure of physics' mysteries that ultimately captured her interest.

Giulia completed her undergraduate and Master’s studies at the University of Milan and PhD at LENS in Florence under the supervision of Giovanni Modugno, studying the effects of disorder on the transport of quantum particles. She continued to work at LENS as a postdoctoral fellow under the supervision of Marco Fattori, investigating quantum droplets. Giulia subsequently joined Harvard as a postdoctoral fellow in Misha Lukin's group to work on neutral atom arrays for quantum information. Building upon this experience, she is leading her own lab at Harvard which plans to explore new scientific avenues of using a two-species atom array for quantum science.

By Danilo Shchepanovich, and Yi Zhu

April 13, 2024

In an atom array experiment, researchers use lasers to cool a vapor of atoms to very low temperatures (~few uK, or almost absolute zero!). They then trap individual atoms within tightly focused beams of light called optical tweezers. With many optical tweezers, researchers can form a 2D array of atoms and further manipulate their electronic state and mediate interactions between neighboring atoms. Finally by shining another laser on the atom array and observing the fluorescence of each atom, they can readout the state of each atom.

Why would scientists want to manipulate and detect the electronic states of an array of trapped atoms? Each atom can be used to encode a quantum bit (qubit) analogous to the zeros and ones that your computer uses to compute. However, quantum bits exhibit non-classical behavior such as superposition and entanglement, which forms the foundation of many clever quantum algorithms for computation that are more efficient at solving problems challenging for a classical computer.

The highly-entangled nature of quantum states is also what makes many areas of physics, chemistry, materials science, and even biology challenging to understand and simulate. Amazingly, researchers can generate entanglement across an entire atom array. With this capability, Giulia’s group plans to use their experiment to model interesting physics (e.g. lattice gauge theories, topological phases of matter), solve problems in quantum chemistry, better design materials, and maybe even tackle unsolved challenges in biology.

As our HQI community grows larger, we’d like to offer insight into the individuals who make our innovative research possible. In the following interview, Prof. Semeghini takes us through her scientific journey – from an early interest in physics to leading a lab of her own. Our conversation has been edited for ease of reading.

What sparked your interest in science? Can you recall when you realized that you wanted to pursue a career in science or a related field?

GS: Certainly. Since childhood I've always been naturally curious about how things work. However, I didn't necessarily know that I would end up in science at that point. It started to become more clear during my high school years. In my third year, I went to a big cultural event in Italy, where I saw an exhibit prepared by a group of physics university students about extremes in nature (small and big, hot and cold etc). Something clicked while I was listening to this person telling me about all these fascinating phenomena. It felt like that curiosity I always had was resonating with what was in front of me and highlighting a path. After that, I looked at my physics class with renewed interest and I noticed that, when I was studying with classmates who were struggling in physics, I had a lot of fun trying to rethink the problem in new and simplified ways and create small experiments to help them understand. It was in those years that science and physics in particular started to become an option for my future career. 

Was the decision to go to college and study physics an easy one for you?

GS: In Italy, after you graduate from high school and enroll in university, you choose your discipline immediately, so it’s a big decision. I had a lot of different interests. My top choice would have been journalism. However, the path to become a journalist was not very clear. I had to study something in the humanities and after that try my luck and find opportunities to write. I also had a desire to become a lawyer, but my brother was already in law school and I was determined to do something different. Physics was an option that had gained a lot of ground during the last years of high school. What drew me in was that it was a bit more of a mystery: it was not the prospect of a specific job but the discipline itself that fascinated me. I knew that there was a lot more to explore than what I learned in my high school class and so I ended up choosing physics.

Could you share any standout moments from your studies or memorable experiences during grad school?

GS: The first one is certainly the quantum mechanics course I took during my Bachelor’s. It was another moment like the one in high school, when you find your match, something that draws you in. Another one happened when I was finishing my Master's in Milan. I was exploring PhD opportunities, when a friend studying in Florence mentioned their experiments involving ultracold atoms. During my visit to their lab (at the European Laboratory for Non-linear Spectroscopy - LENS), I witnessed two BECs (Bose-Einstein condensates) interfering in their experiment, which left a lasting impression on me. I studied matter-waves in class, and the abstract idea was already extremely fascinating, but when I saw it… it was a whole different story! I instantly decided that I wanted to go there. That was the first and only place I visited. I was just immediately convinced that that was my place.

My experience in grad school was quite intense. It's a three-year program in Italy, so it demands a lot of your time to get results within a relatively short period. Being in the lab was fantastic! It’s a special feeling when you're doing an experiment and you're uncovering all these new things – some match your expectations, but then there's a lot that doesn't and leads you into new directions.

Of course, there were ups and downs. One challenging moment happened when I was a postdoc in Marco Fattori’s group. I remember a particular day, as we were getting toward the end of a project, one morning my younger colleague urgently called me. In the background, the whole room was buzzing with beeps. It turned out we had a vacuum leak. I recall the frustration vividly. That day I was sitting on the floor, feeling quite lost for hours. 

However, situations like this are part of the challenge, it's something that deviates from your plans. Our work is centered around discovery, which means sometimes things don't go as expected. But that's also what makes it enjoyable. It means there's a chance for something beyond your initial imaginings to emerge. In the following weeks, trying to restore the vacuum, I learned a lot of new things and we actually had quite a lot of fun!

Were there any mentors or role models who guided you through your grad school journey? Do you carry a piece of advice from that time that continues to influence you today?

GS: Certainly! I've been very lucky. I had great advisors throughout my PhD and postdocs. Not just good scientists but people who have helped me a lot. My career was not a very straight path and I had a lot of doubts along the way. After staying in the lab in Florence as a postdoc for a couple of years, I remember trying to decide if I wanted to go abroad and look for another postdoc or go do something else. I went to my PhD advisor, Giovanni Modugno, and I told him: I don't know if I'm really cut out to be a scientist. When I compare myself to my colleagues who I think are good scientists, they're different. For example, these people could recite everything they had learned by heart. My memory is terrible: I have to relearn things all the time. I thought that if I wasn’t like them maybe this was not what I was supposed to do.

I remember him walking, then he stopped and looked at me and said “You're looking at this completely in the wrong way. There is no image of the perfect scientist. There is you and there is the work that you're doing. Is it fun? Is it successful? Is it working? That's the only thing that you should look at. Because otherwise, if you keep comparing yourself to others, nothing good or new will happen; thank god, you're different!” I never forgot this dialogue, it was of crucial importance throughout my career.

What is the role of collaborators in your research?

GS: To me, it's a crucial part of what we do. Research doesn’t happen in isolation. Instead, the best ideas that have happened in my career have always come from discussions with other people; and generally, these ideas have been the intersection of expertise from different people.

Also, it is something that supported me throughout my PhD and postdocs. Sometimes it's a strange job that we have, it's all about keeping the motivation, looking for new goals, and being excited about new problems. Talking to other people in my scientific community and beyond is extremely important because it fuels my curiosity and keeps my excitement for the job alive. Otherwise, if you're not curious, you don't do research.

Are there any publications or research results that you're particularly proud of?

GS: There are many, all for different reasons. But the ones you cherish the most tend to be the ones you poured the most effort into, so the ones I led. Specifically, my recent spin liquid project was quite special; it kind of changed my career. It started during COVID, while we were still stuck at home, from conversations with theorists at Harvard who had a new proposal for us. It was a really cool idea, we were immediately excited but there were a lot of things we didn’t know how to do. Going through the whole process, trying the first measurements, seeing the first experimental signatures, getting stuck, trying different solutions, and discussing for hours with the whole team that was involved in the project, was great! A lot of hard work but also a lot of fun. And in this case, the result was one of the most exciting things I stumbled upon in my career.

How do you view the state of the field currently? What are the sort of challenges? And how do you think they will evolve in, say, the next 10 years?

GS: I think the field is in a very exciting stage. There are so many new generations of students getting involved in quantum science, and many new ideas are coming out all the time. There is incredible promise in this field, but at the same time we still don’t quite know where we can ultimately get and how We have ideas for the near future (how to improve the platforms, first/second generations of applications to explore) but there’s a lot more beyond that that we still need to figure out. I think we will gain a lot by creating more and new connections within our scientific community and beyond. This will help foster new ideas and better understand what are the fields where quantum computers could really have an impact. We need to stay open and ever more curious. 

Throughout your career did you have any challenges related to gender? Could you give advice for young women who might be interested in building a career as a scientist?

GS: I’ve been the only woman in the groups I’ve worked in for most of my career. I didn’t mind it, but I certainly felt it. It contributed to that “feeling different” I mentioned before. Again, when I was talking to my PhD advisor, he did help me notice that being different, also in very simple ways like gender, is a richness and not a problem. But I needed to be helped to see this and I am grateful that someone did. 

The advice I would give to other people is more or less the same one I received: focus on your own path, try to figure out what you are passionate about and what is the path to pursue it. Find people who can support and guide you. Don’t waste time measuring yourself against others; that often gets you into trouble. And be brave! It is always worth trying! 

Do you have any advice for young students who would like to enroll into a graduate program in quantum science?

GS: It is going to be fun! Whatever brought you here you will find a lot of new and unexpected things. Try to follow what triggers your interest and your creativity, not just what is fashionable. Keep your eyes wide open to all that happens around you, in grad schools, in the research groups around you, and around the world. Learn as much as you can and try to find people who are excited about what they do!

Learn more about Prof. Semeghini's research and team through her group website.