Editor’s note: This is part of a series of profiles of scientists and engineers from across the Chicago Quantum Exchange member institutions.
Jens Koch did not expect to join the field of quantum information science. His PhD was focused on something much different: the idea of using single molecules as transistors.
But when he met Steve Girvin at Yale University, a theorist studying superconducting qubits, he made the decision to change the direction of his research, despite having very little experience in the field of quantum computing.
“I was really impressed and really wanted to work with him,” Koch said. “So for my postdoc, I sort of jumped into the cold water headfirst.”
Now Koch has been conducting theoretical research on superconducting qubits as a professor at Northwestern University for 12 years. After doing the math, he laughs and says, “Time goes by quickly when you’re having fun!”
And there’s a lot of fun in Koch’s life at the moment: his group is involved with two of the five National Quantum Information Science (QIS) Research Centers funded by the U.S. Department of Energy Office of Science. One is the Superconducting Quantum Materials and Systems Center (SQMS), led by Fermi National Accelerator Laboratory. The other is the Co-design Center for Quantum Advantage (C2QA), led by Brookhaven National Laboratory, Princeton University, and Yale. In both centers, he and his students do theoretical work that drives new techniques and designs for superconducting qubits.
“I thought that the way things work is, you buy two lottery tickets, just so that your chances to win are twice as high,” Koch said about his decision to join both proposals. “I hadn't really planned on winning twice. It’s really exciting, and it's also lots of responsibilities. As a result, my group has grown quite a bit.”
Along with the research he does for SQMS and C2QA, he has also developed an open-source Python code library called scqubits, which simulates superconducting qubits. It provides researchers with a convenient way to predict properties of different superconducting qubits without having to build them in the lab and has been downloaded more than 70,000 times.
“I’m really excited about it,” Koch said. “It actually gave me an excuse to do some coding myself again, which is something I really enjoy but I don’t always have time for.”
When he considers the future of the field, Koch said he fluctuates between optimism and skepticism for the promise of large-scale quantum computing; but no matter what, he said, the quantum revolution has a great deal to offer the world.
“As my colleague Scott Aaronson once noted in a TED talk: if it was true that there is something fundamental that will keep us from ever building a quantum computer, then we will find out by doing this research,” he said. “And so, on the bad days when I wonder whether we will have a large quantum computer anytime soon, at least I can tell myself that if we don't, then we’ll likely actually learn something much more exciting about quantum mechanics that we did not understand before.
“But I think this uncertainty, anticipation and sometimes hesitation as to what might happen—to me, that is what makes it more fun. If there was a clear roadmap, why should I still work on it?”