Quantum Q&A With Leo Lo, CC’22

Leo Lo has always enjoyed physics. In middle school in Hong Kong, a Physics Olympiad Club mentored by older students introduced him to cool new topics and gave him a chance to ask questions about subjects he knew nothing about. 

“Physics is such an elegant and efficient way to describe the world around us,” he said. 

He had an initial interest in astronomy but decided to pursue a more hands-on discipline. In high school his family moved to New York’s Long Island, where Lo got his first taste of research in a condensed matter physics lab studying quantum materials at Stony Brook University. The PI, Mengkun Liu, had previously been a postdoc with Dmitri Basov, whose lab at Columbia specializes in using light to study quantum materials. 

Lo enrolled at Columbia College as a physics and math double major and got involved with the Basov Lab. While at Columbia, he worked on several quantum projects; was named Goldwater Scholar, Rabi Scholar, and, most recently, Phi Beta Kappa; and has been an active member of Columbia Pops.

Lo will head to Harvard for his PhD in the fall. Before he trades the Big Apple for Beantown, we asked him to reflect on his time at Columbia. 

What were some of the most exciting projects you worked on in the Basov Lab?

My freshman year, I helped build a python package to calculate the optical properties of quantum materials. These calculations are complicated to do by hand, and now the lab has an in-house code to make things easier. 

With that code, I was able to detect a unique quasiparticle called a Cooper Pair Polariton in a type of quantum material composed of layers of graphene and superconductors. The lab then tested for these experimentally, and found them! That was really cool to see my calculations play out in real life. 

What’s so exciting about quasiparticles?

They are a starting point for a lot of potential applications. Take electronic devices like our phones and computers: these are based on the movement of electrons, but they consume a lot of energy. Especially things like supercomputers—some can use as much energy as entire towns! But electrons aren’t the only way to transmit information. We can also think about using different kinds of quasiparticles instead, which could use less power or be even faster. 

They can also help us understand how to classify different materials. A big goal among scientists is to create a “periodic table” of matter. Knowledge about existing materials can help us make predictions and discover unknown ones with novel properties. 

Why do you like condensed matter physics? 

It’s a field where theorists who make predictions work closely with experimentalists who test those. I’ve really enjoyed that back-and-forth, collaborative environment. It’s also unique in that, rather than using reductionist reasoning to come up with fundamental laws, you get to combine things in different ways to try to produce new phenomena. 

Take twisted bilayer graphene. A few years ago, researchers found that it’s capable of superconductivity, which is the resistance-free flow of electrons. It’s amazing that you can take two atom-thin layers of the same material and just by twisting them produce something totally new.

There’s still a lot to learn about superconductivity, and I want to contribute to that research as I continue on in my career.

Which you’ll be doing at Harvard?

Yes, I’ve enrolled in a Physics PhD program there, where I’ll be advised by Ashvin Vishwanath. I’ll be pivoting more to theoretical research on superconductivity in twisted bilayer graphene, and on the geometry and topology of quantum states. I love visualizing things, and this kind of research explores how the shape of a material influences its properties. 

Who has helped you along the way? 

The whole Basov group has been super supportive of me, and I worked a lot with Alex MacLeod, a postdoc in the lab. He really helped me get through my projects. 

My time in the lab has helped broaden my horizons. I thought as a physics major I would just talk to physicists for the rest of my life, but Dmitri's lab works with collaborators all over who study quantum materials. I really developed an appreciation for interdisciplinary research, and how beneficial it is to share ideas with people from different backgrounds.

What have been some challenges you faced at Columbia?

I had the chance recently to work with some theoretical researchers outside of Columbia and while we were writing up the results for publication, I realized we had made a mistake in a calculation. That was really stressful because it could have invalidated one of the main conclusions of a project I had been working on for almost a year. Thankfully the correction didn’t change the results, but it taught me that I need to be a little more careful and always re-check my work. 

More broadly, it was challenging at times to balance research with my course load during the pandemic. There were times I definitely felt like I was burning out and isolated. Those moments taught me a lot about how much I could really stretch myself, and when I needed to take a break and recharge.

What are some activities that help you recharge?

I play the flute for the Columbia Pops Orchestra. It’s an entirely student-run club, and we chose different movie soundtracks and things like that to perform. We practice on Saturdays, and that’s my time to recharge. Music lets me access emotions that you can’t always tap into with physics.

I also experiment with making my own music with GarageBand. That’s a bit like research—in both, you’re trying to create something that has never existed before, which I really enjoy.

Any advice for future Columbians?

There are so many great opportunities available, but you have to take some initiative to find them. Don’t be scared to reach out to people for advice and to get involved. 

And enjoy the core curriculum! That helped me grow as a person and appreciate topics like literature and art that I don’t think I would have been exposed to otherwise.