Enchanted by science as a child, Yale physicist now probes quantum riddles

In an interview, Yale quantum physicist Charles D. Brown II reflects on his entry into the scientific life — and his research in quantum simulation.
Charles Brown

(Photo by Andrew Hurley)

The next time you’re at the public library, be sure to make a mental note of the kid at a nearby table soaking up a biography of Albert Einstein. That kid might be the next generation’s Charles D. Brown II, quantum physicist.

Brown, who joined Yale's Faculty of Arts and Sciences as an assistant professor in the Department of Physics last month, fell under the spell of physics in middle school at his local library in Las Vegas, where he read about Einstein and his work in gravitational physics.

Brown would go on to earn an undergraduate degree at the University of Minnesota, a Ph.D. in physics from Yale in 2019, and conduct postdoctoral research at the University of California-Berkeley.

He received the National Science Foundation Graduate Research Fellowship in 2014, the D. Allan Bromley Fellowship for Graduate Research in Physics from Yale in 2017, the National Academies Ford Foundation Dissertation Fellowship in 2018, co-founded the Yale League of Black Scientists, received a National Academies Ford Foundation Postdoctoral Fellowship in 2020, was awarded the 2021 Quantum Creators Prize, and is one of the lead organizers of #BlackInPhysics week, an effort to recognize and promote the scientific accomplishments of Black physicists.

In an interview with Yale News, Brown discusses what sparked his curiosity about the universe, the scientific discovery that continues to amaze him, his own research into the exotic properties of quantum materials — and why his life as a scientist is so much more dynamic than he ever expected.

What originally sparked your interest in science?

Charles Brown: As a young child, my mother instilled in me a deep curiosity about the universe. Even to this day, I cannot remember a time my mother wasn’t entranced by the presence of the moon, the ostensibly precarious position of Earth relative to the sun, the idea of our solar system zipping around the Milky Way galaxy, and thoughts on the existence of other Earth-like, life-harboring planets.

Although she was not a woman of great monetary wealth and not a scientist, she was rich with intellect and passion for learning about everything around her, especially science. Because she was my first teacher and mentor, I absorbed these qualities from her, placing extraordinary importance on learning and scientific inquiry.

Are there other scientists in your family?

Brown: No, I’m the only scientist, but there are many science enthusiasts in my family! In fact, I was the first in my extended family to earn an undergraduate degree.

When did you pick physics as your main field of study, and why?

Brown: As a child I had no Internet at home and was a frequent visitor of the local public library (support public libraries!). During my middle school years, I stumbled across books about Albert Einstein at the library and I became deeply fascinated by his work on gravitational physics and the emission of light from atoms.

After years of cannibalizing electronic devices around my house for scrap parts to build interesting things — much to my mother’s delight and chagrin — I settled on majoring in engineering in college but maintained a deep interest in physics. In college I quickly realized that, while I love building and designing things, I was most interested in how things work and why they are the way there are, so I switched to majoring in physics and found that experimental physics is right up my alley.

You’ve done innovative research with quantum simulations. Can you describe that work?

Brown: My work on quantum simulation involves constructing experiments that allow a relatively simple quantum system to emulate the behavior of a more complex quantum system. Let’s start with an analogy. Imagine an egg carton with marbles in it, with marbles hopping from bowl to bowl within the carton. Also imagine that when a new marble enters a bowl in which a marble is already resting, the two marbles bounce off each other. It turns out that this simple model can describe some intriguing properties that appear in the physics of real materials.

In materials, electrons hop around and bounce off each other. The details of that activity set many of the materials’ properties. In my work, I build arrangements of bowls made of light and study how extremely cold atoms hop around these bowls, which allows me to emulate aspects of real materials and to study the exotic quantum properties that emerge within these interacting quantum systems.

What scientific discovery has interested you the most in recent years?

Brown: While there have been several important and intriguing scientific discoveries in recent years, the one that continues to blow me away is the detection of gravitational waves, for which the 2017 Nobel Prize in Physics was awarded. That incredibly massive black holes can travel at near light-speed before crashing into each other and emitting so much energy that ripples in the fabric of spacetime itself (gravitational waves) are launched into the universe, and that these ripples cause the length of everything to expand and contract, will never cease to amaze me. The more I think about it, the more I’m in awe of how incredible the universe is.

What area of research intrigues you the most going forward?

Brown: My research interests lie in the quantum mechanics of systems with many particles, as this physics relates to quantum materials (materials for which the uniquely quantum effects of coherence and entanglement are crucial to describe the material properties), and how concepts from mathematical topology and differential geometry play a role in the emergence of the exotic properties of quantum materials.

How is the life of a scientist different from what you envisioned as a student?

Brown: My life as a scientist is so much more wonderfully dynamic than I thought it would be. When I was a student, I thought that as a professional scientist I would be working on something in the laboratory all the time. But in actuality, I build experiments in the laboratory, I write code to control scientific instruments and collect and analyze data, I do long pen-and-paper physics calculations, I do numerical calculations with Python and Mathematica, I build 3D CAD models, I travel the world and discuss science with other scientists, I strategize and budget for laboratory operations, I mentor and teach students in my laboratory and beyond, and I write … a lot!

What are you most passionate about outside of the lab?

Brown: Outside of the lab I’m passionate about building a wonderful life with my wife; addressing equity issues in the academy, and building community among physicists, especially among those underrepresented in the physics discipline; being a good role model for younger people and my peers; and engaging the broader public with science to do my part to create a more informed and scientifically adept society.

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