Everything Is Everything

Xie Chen is a theorist working at the edge of science and engineering, where ideas straight out of science fiction abut the future of computing—and, thus, the future of our plugged-in society. Nominally, she’s a condensed matter physicist exploring quantum systems. But Chen isn’t concerned with neatly drawn lines between disciplines.

“The study of physics is not just physics,” says Chen, an associate professor of theoretical physics and a member of the Institute for Quantum Information and Matter (IQIM) as well as the Walter Burke Institute for Theoretical Physics at Caltech. “I’m also learning about information science and computer science. I’m using math, like topology and category theory. I share with many experimentalists and en­gineers the same big goal: revolutionizing the next generation of information processing and computation. In this field, everything is everything.”

Weirdness abounds in Chen’s world.

Start with the simple actions of particles at the quantum level. Here, the classical rules of physics break down, yielding what Einstein called “spooky action at a distance.” At this scale, two faraway particles can affect each other. An observer can be sure where something is but not how fast it’s going—and vice versa. A particle can even seem to be in two places at once.

Then pull the camera back to view not just one or two particles interacting, but hundreds of thousands of them. This is the sweet spot of Chen’s research. Quantum structures that emerge out of such huge systems can twist in upon themselves to form complex topological shapes, like the mobius strip. And their configurations can produce strange behaviors—such as conducting electricity on the surface while being insulating within.

Starting from these fundamentals, Chen is contributing to the grand endeavor of realizing the quantum computer. Such a machine would be exponentially faster than today’s technology and capable of solving immense, complicated problems that are untouchable now. One puzzle Chen is helping to piece together is quantum memory—how to overcome the fragile nature of quantum information to create durable storage.

It’s about Perspective

This reach into other disciplines is what first drew Chen to quantum physics. Years later, she retains her passion for interdisciplinary collaboration. Beyond exploring big ideas and plotting the future of computing, she enjoys the intellectual connections that form in the process.

“When I start to talk with other researchers, I learn their language and I learn their way of thinking,” Chen says.

“Left to myself, I use my favorite approach to deal with problems I am interested in. But I don’t want to get too comfortable with that. Meeting regularly with people from other fields—learning about their interests, their techniques, and even their cultures, and brainstorming about how we can collaborate—helps to widen my perspective, to drag me to thinking about the other side of the problem. Sometimes it’s not about knowing or not knowing—it’s about perspective.”
- Xie Chen

How does the human mind wrap itself around the elaborate and abstract concepts Chen and her colleagues examine? The key—as with many parts of life—is not to get too hung up on the details.

“The space is so big that even simple questions can be very hard,” Chen says. “But why do we care about so much detail? In fact we don’t. We care about global properties—things that stay pretty much the same from system to system—and the exotic behaviors that emerge.”

She compares her bigger-picture approach to inspecting an Impressionist painting.

“When I stand very close to those pictures, there are patches of color that look like they’re put together randomly, in no particular order,” Chen says. “Once I step back, I suddenly see the scene the painter was creating. That’s exactly what we find in quantum many-body systems. If you look too close, you see a bunch of randomness. Then, when you step back, you see all these unusual properties emerging out of something so simple and ordinary.”

Expanding the Scope

Philanthropy has been an enabling force for Chen’s studies. She interacts with postdoctoral scholars who have received fellowships from the Burke Institute, which was established with a gift from the Sherman Fairchild Foundation, as well as from IQIM, which grew out of funding from the Gordon and Betty Moore Foundation.

In addition to the tangible support, Chen places a high value on the sense of community these scholarly institutes foster. In these environments, ideas hop back and forth between subspecialties, building excitement among scientists.

To Chen, supporting this lively community is not just about the technology of next year or the next decade.

“This is an exciting time for quantum physics, because the progress is so great that industry is taking notice and trying to create the first quantum computer,” she says. “To give to Caltech is to help build things even beyond that. If companies are putting up a single building, we are expanding the foundation so that more buildings can go up later on. That’s the scope of it.”


Giving Priorities