Jeff Thompson, Associate Professor of Electrical and Computer Engineering at Princeton University, received his B.S. (Physics, with exceptional distinction in the major) from Yale and was a recipient of the Howard L. Schultz Prize in 2007. His senior advisor was Jack Harris. Thompson went on to receive his Ph.D. from Harvard in 2014. He joined the Princeton faculty in 2016. We asked Dr. Thompson a few questions about his research; see below for the interview
What kind of research did you do in the department? And where?
I was fortunate to have several great research mentors during my time at Yale. In the summer after my freshman year, I worked with Dave DeMille and his graduate students Jesse Petrika and David Glenn on buffer gas cooling of molecules. My project was to do numerical simulations of the cooling process, and evaluate designs for an electrostatic guide for cold molecules. I learned a lot about both atomic physics and numerical methods.
The following summer, and for the rest of my time at Yale, I worked in the lab of a then-brand-new assistant professor, Jack Harris. Together with the first graduate students Ben Zwickl, Will Shanks and Andrew Jayich, I helped set up the lab in SPL 16/17. We did some really cool experiments in the field of optomechanics – exploring quantum mechanical coupling between light and a mechanical oscillator. The main result during my time there was demonstrating laser cooling of the motion of a mechanical membrane from room temperature to < 10 millkelvin above absolute zero. While such laser cooling was routine for atoms, it was neat to be able to apply the same thing to a macroscopic mechanical system (in this case, a mm-sized silicon nitride membrane).
What kind of research are you doing now?
I started working on atomic physics during my PhD and postdoc, and now work on applying atomic physics tools to the development of quantum computers. Quantum computers process quantum states of information—with bits in superpositions of 0 and 1 at the same time—and may someday be able to solve intractable computational challenges, such as simulating the behavior of materials and chemicals. My group started out exploring new physical platforms for quantum computers. While this is an area of research that has been active for 30+ years, our understanding of what is important keeps evolving, opening new paths and fueling new ideas.
The biggest single effort in my group right now is based on neutral atom qubits using ytterbium atoms. We developed the counterintuitive idea that it’s better to encode the qubit in an unstable excited state of these atoms, because it causes most errors to result in transitions back to the ground state that can be easily detected. While this doesn’t give you any advantage if you only want to use a few qubits, it may reduce the overhead you need to run error-corrected computations with millions of qubits by a factor of 10 or more, because these detectable errors can be fixed much more easily.
My favorite thing about this research is how broad and interdisciplinary the day-to-day activities are, which provides a lot of intellectual stimulation and opportunities to learn new things. In addition to our prototype quantum computers (which are room-sized apparatuses with a few tables full of lasers and vacuum chambers), we currently have projects running on the theory of quantum computing and quantum error correction, exploring different architectures for real-time electronic control systems, prototyping new kinds of optoelectronic devices, and fundamental spectroscopy of ytterbium atoms.
As a scientist, can you describe what you do on a usual day to conduct your research?
I split my time between discussing research progress and analyzing data with the graduate students and postdocs in my lab, reading papers and trying to come up with new directions, and the administrative work that comes with running a research group (grants, budgeting, etc.). I aspire to spend more than 75% of my time on science, and usually succeed over a suitably long averaging period.
How did your time in Yale Physics prepare you for what you are doing now?
The first thing that was helpful about my time at Yale was the quality of the instruction, with small classes and dedicated teachers. This started right away with PHY260 during my freshman year, taught by Prof. Girvin at the time. I remember a particularly pivotal discussion during office hours, where I worried about whether there was anything left to do in the field of physics. Prof. Girvin convinced me that there’s a lot more to physics than fundamental particles: it is also the language to describe emergent phenomena in complex systems, which are basically unlimited. This includes condensed matter, but also quantum information (ie, what is going on in a quantum computer), neural networks/AI, etc. This has shaped my notion of the field since then.
Once I got started with research, I also benefited from close mentorship from my advisors, Prof. Harris and Prof. DeMille, and their graduate students, and the opportunity to tackle real, cutting-edge research problems.
Finally, I really enjoyed the intimate and friendly community in the SPL basement (at the time, the DeMille, Barrett, McKinsey, Harris groups, among others), who were always eager to talk about research or help solve a problem. The machine shop and electronics shops were small but allowed researchers to do pretty much anything they needed to, even at midnight. An environment like that is very empowering, especially for young researchers.