Interview with Professor Joseph Falson

Interviewer: Audrey DeVault


Dr. Joseph Falson joined Caltech’s faculty in 2019 as a visiting associate with the Department of Applied Physics and Materials Science, and became an Assistant Professor of Materials Science in 2020. His research focuses on the synthesis and characterization of quantum materials that display emergent functionalities. Dr. Falson received his B.S from the University of New South Wales (2009), M.S. from Tohoku University (2012), and Ph.D. from the University of Tokyo (2015).


  • Favorite food: Very good sushi; I did my PhD in Japan and was exposed to very good sushi by my seniors. I go very seldom, but I appreciate it.
  • Favorite country: Japan. It is one of the most beautiful countries on earth. It’s got everything, it’s really quite an amazing place.
  • Favorite musical genre: I enjoy all types of music, but I have recently been enjoying LA’s KJazz 88.1 radio station. It’s quite famous, and you can stream it from around the world; it’s fantastic!
  • Favorite theory/effect: The Fractional Quantum Hall Effect. It is a very beautiful, complex, layered, and emergent property of condensed matter systems. It deals with the concept of a system as a whole being more than the sum of its parts. The effect only emerges in many-body systems and is very difficult to predict a priori. It is nice to find properties of materials that are difficult to predict theoretically (and be ahead of the theorists). It’s very curiosity driven.
  • A fun fact most people don’t know: Most people don’t know that I’m Australian. I haven’t lived in Australia in about 10 years now, so it’s very rare that people pick up on my accent. Of course, Australians would hear me and know, but otherwise it’s difficult for people to pinpoint.

What type of research does your lab focus on?

Probing the fundamental properties of nature. Specifically, we look at crystalline materials. We grow crystals in “thin film” form, on the scale of 10 or 100 nm thick. When crystals are made very thin, their properties begin to change due to dimensionality effects. In quantum mechanics you may have seen the example of a quantum well, where the energy levels in some spatial direction become quantized. So now you have a combination of very subtle material properties that are built into the crystal structure, and you can perturb it by making the crystals into the shape that you want.

The reason why we try to make really clean crystals is because if you have crystals that are highly defective, and electrons inside them, the electrons will begin to feel the effects of the lattice much more than the effects of the other electrons. So in some situations, the lattice becomes like a secondary property, and we can begin to see the subtleties of how the electrons talk to each other while dressed in some property of the lattice. Usually these properties are very delicate, and only appear in the cleanest materials, often at very low temperatures (about 1 K).

What motivates your research?

We are motivated by the search for new paradigms. Scientists are often asked about the real-world applications of their research, but for us, it isn’t about creating a new material for use in phones or cameras. We are focused on the exploration of fundamental properties of nature.

That’s not to say our research won’t have amazing applications in the future; everything around us started out as fundamental research. Semiconductor science used to be considered uncontrolled and unimportant in comparison to other more well-understood, controllable fields like chemistry and biology. But now I am looking at a billion semiconductors on my screen. Lasers too; when the laser was invented, it wasn’t clear what its applications would be. But now our internet service is based on fiber optic cables across the seas. So just because an application is opaque at the outset doesn’t mean that it’s going to remain that way going forward.

There aren’t that many places where you can pursue pure, fundamental science like this, but Caltech is one of the few places that you can.

How did you get into Materials Science?

100% by chance, I have had a very long and winding road to get here. I was dedicated to doing medicine when I entered university but found very quickly that it wasn’t for me. I graduated with an undergraduate degree in chemistry, but at that point I was already sure that I didn’t want to do traditional wet chemistry. But I didn’t have a great idea of what I wanted to do, I just knew I was interested in electronics and crystal growth.

My 3rd and 4th year of undergrad I explored outside of my chemistry coursework and took some physics and materials science courses and found that I enjoyed semiconductor physics. When I began applying to grad school, I applied for a Japanese government scholarship that I had been introduced to in a humanities course, and won it. So I cold emailed some professors in Japan. I met with a few chemistry professors, and one directed me towards another potential mentor he though I would click with, who studied crystal growth and materials physics.

It was like falling in love in a scientific sense.

I had a very good connection with the mentor he directed me to. So I applied, got the scholarship, got into the school, and then went there for 5 years and got my PhD. I had an absolutely fantastic time. A lot of stars aligned. From there I made another international connection that led to a postdoc position in Germany for four years, and then applied to Caltech, and got the job. I was just driven by my gut feeling.

What I try to tell my students is that in life, the key to success is finding something you are able to do for 10 hours a day and not grow to hate it. If you want to be top-class successful at anything in life, it doesn’t matter how smart you are if you don’t put the time in. Especially in experimental science, so many things go wrong, and you encounter such difficult procedures, so you have to just be tough. I never get up and go to work and want to go home, and I hope that the people around me find that as well.

What have been some of the challenges and rewards of building a new lab? (How has the pandemic affected things?)

Everything has been challenging because it’s been very difficult to get extra manpower, and everything gets delayed. A lot of the equipment is now set up, but I had to do that 100% with my one student. For the vacuum equipment, usually a team would have flown in for two weeks to set it up, so it was quite a monumental task, and it’s taken us about 3 months of work. The good thing that’s come out of that is that now I know that machine like it’s the back of my hand. That’s my baby now, I know all the intricate details. So as hard as it’s been, I’m pretty happy.

What do you think is the most exciting new development in materials science?

I would say the most exciting thing isn’t necessarily a development, but more of a tide change. Early on materials science was very much semi-conductor based, because they were novel. Then the field moved on to studying a select class of very high quality semiconductors very intensely. But now we know nearly everything about them, so recently 2-D materials have been a big thing, and we are entering a stage where there is a strong appetite for a large variety of materials. The field is maturing to be more interdisciplinary, and the tide is shifting towards a search for more exotic, highly crystalline materials. The momentum has grown a lot in recent years, and there are a lot of new computational tools that help predict new materials instead of just doing blind experiments. Theorists are using machine learning and large data sets to make these predications, and it enriches my half of the problem.

What does your typical day look like? What do you do in your spare time?

On a typical day I go to lab at around 8 am, I talk with my grad student and we discuss our goals for the day. Then we try to focus on setting up equipment. I teach twice a week, and spend a lot of time planning and thinking about my lectures. My days are sometimes pretty long and difficult, and physically challenging as well, but it’s nice to see something set up at the end of the day.

In my free time I like to garden. I like it because it takes me 100% away from thinking about anything academic or sophisticated. I also like the idea that it’s like multitasking. When I’m at work, the plants are also hard at work growing.

My wife and I recently bought a house, and there are a lot of things we need to fix up, so at the moment I spend all my weekends sanding or painting. But it’s fun to be free to build stuff how you want it.

What is it like to travel the world as a scientist?

Attending international conferences and talking to people has resulted in a lot of collaboration, friendship, and support. Science is a very natural way of bridging boundaries.

Obviously, it is very different from a vacation as you are traveling to work, but I do think that its incumbent on scientists to enjoy their time while traveling. I think it’s one of the major perks of being a scientist.

I try to travel internationally as much as possible, though I will admit I am enjoying this one year where I don’t have to travel. In the year before I came to Caltech, I would fly from Europe to Caltech for a meeting, and then fly home the next day. There were some hard days and lots of 15 hours flights, so I am enjoying not travelling this year.

What do you love most about Caltech?

I like that science is the number one priority. Caltech places a lot of trust in its students and staff, including young people like me, and I enjoy the independence. The weather, and the campus are also very nice; it’s a beautiful place. There’s something special about rolling up to Caltech and going to the Athenaeum; it’s a very unique experience, very dignified.

I am very passionate about undergraduate mentoring, and I like that undergrads are strongly encouraged to participate in research.

What advice would you give to your younger self/Caltech undergrads?

Reflecting on my undergrad time, I didn’t have a designated advisor. I was very naive and was very lucky that everything worked out. I wish that I had forged a relationship with a mentor when I was younger and had someone to guide me. Luckily, I did have a mentor in graduate school, and that’s when my career really started to take shape. I would recommend you take full advantage of having an advisor. Especially going into your 20s, you think you know what’s going on, but looking back now, I had no idea. You should hunt for a good mentor, it should be someone who can advise you in research and courses, who is also in tune with your personal needs. A good mentor is a good human.

I would suggest you get involved with a lab as heavily as you can, and that you should think about lab work not as something tangential to your studies, but as your life education. It’s what they’re not going to teach you in class. I think you should take the most difficult classes possible in the first three years, research whenever you can, and then do a senior thesis. I personally didn’t do a senior thesis, and I 100% regret it. I have plans for every undergraduate in my lab to do a senior thesis. I strongly encourage it, because that’s what is going to be the most useful when applying to grad school.

Above all, though, you’ve got to have fun and challenge yourself.

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