Deep in the organ pipes

Of course, he also had his bicycle with him in California, after all, Rami Barends is Dutch: The physicist did research in America for more than ten years, and while he was still getting used to the new living conditions there at the very beginning, a car almost knocked him off his bike. "It turned out that a colleague's wife was driving, luckily nothing happened," says Rami Barends, and then he adds with a smile, "At least the incident earned me a very nice dinner with the colleague's family!"

A few months ago, Barends arrived back in his native Netherlands: He has been appointed director at the Peter Gruenberg Institute at Forschungszentrum Jülich, and has settled a few kilometers away on the Dutch side of the border. He has since returned to the vicinity of Delft, where he grew up, studied physics and earned his doctorate, although he was not yet working on quantum computers at the time. In any case, choosing his subject was a slow decision-making process: "I would have been very interested in aeronautics, for example, but in space or in a vacuum, you come up against limits. Electrical engineering also fascinated me, but as soon as you turn off the power, that's it." He eventually enrolled in physics with a rationale that sounds typical of him: "Physics," says Rami Barends, "is always there. It always plays a role, even in a vacuum and without electricity."

This justification is typical of the now 40-year-old who likes to get to the roots of his questions. This was evident, for example, in his doctoral thesis: It dealt with superconducting detectors and the detection of errors in complex computer systems. "You can think of it like an organ where a bird has flown into one of the pipes," he says: "As an organist, you immediately hear that something is wrong, but if all the pipes are playing at the same time, how do you figure out exactly where the bird flew in?" He threw himself into calculations and measurements, and because new aspects kept coming up, even when he was long finished with his doctoral thesis in 2009, he stayed on at the university in Delft for a few more months and just kept working.

Soon after, Barends received an offer that took his research in a new direction: He was asked if he would like to go to America, to John Martinis' research group at the University of California at Santa Barbara? Rami Barends didn't think twice, after all Martinis was a highly respected, and above all: "My questions about superconducting detectors from the doctoral thesis were more general, but they could just as well be applied to superconducting quantum bits. I found the topic fascinating, so I agreed." What's more, Rami Barends is at home in two worlds, in highly complex theoretical physics as well as in what he calls the "hands-on" area; building the necessary hardware. It was precisely these two talents that he was able to bring to Santa Barbara.

Unbeknownst to him beforehand, he arrived at just the right time. "The whole field of quantum computing was raising tremendous hopes and expectations at the time, but it was far from where we are today," he says in retrospect. He calculated again, he tinkered, he put in untold night shifts in the labs on the California campus. The working group built the first quantum bit, then created a system with five, and eventually with nine qubits, "it was like Lego, we kept building more and more and more, it was going better and better every month." The group was looking at error correction in quantum computations, experimenting with digital simulations of quantum computing processes, and pushing further and further into the field, which was so new at the time. "We were so dogged in the work," Rami Barends says in retrospect, "because we realized how we were laying the groundwork for something bigger."

He and parts of the research group moved to Google in 2014, and his boss John Martinis became the tech giant's top quantum researcher. It didn't change anything about the work itself, but it did improve the environment, Barends says succinctly of the move into business. He continued to build and calculate, he was there when large quantum computers were created, when the Quantum Supremacy Experiment started; these were milestones that still shape quantum research today.

But why then, when in California he was involved in the most exciting projects there are in his field of research, did he move to Jülich? Rami Barends briefly ponders how to explain. "I spent a decade in the U.S., and an incredible amount has happened in that time. Now I've asked myself the question of what I want to spend the next decade doing." He provides the answer right away: While quantum computers have so far proven their superiority based on highly complex computational tasks that are purely theoretical in nature, the goal now is to finally create a new generation of computers that can contribute to solving truly relevant problems. It's a new goal for the next decade, and Rami Barends wants to work on it with a new team. The computer should be "coherent, controllable and scalable," and he wants to contribute to this, and Jülich, with its densely interwoven ecosystem of researchers from different fields, is the perfect location for this; one that can compete well with research activities such as those of large companies.

And the fact that he can return to Europe, even to the Dutch border, also played a role for him. And of course, he took his bicycle back with him.