But what if we dropped the requirement that a quantum computer be as reliable as a regular computer? What if we worked up to Everest by first climbing hills? Broadly, that describes the RQS’s approach, said its director and principal investigator, Andrew Childs, a professor of computer science who also co-leads the Joint Center for Quantum Information and Computer Science, a UMD-NIST partnership.

When quantum computers were first proposed in the 1980s, the idea was to use them to understand quantum systems too complex for classical computers, Childs said.

“One approach to that is you build a large-scale, fault-tolerant quantum computer that you can program any way you want to simulate quantum mechanics,” he said.

Since such computers don’t yet exist, scientists at Maryland have led the way with an alternative approach that is already feasible: analog quantum simulation. “In this case, instead of a digital computer you can use for anything, you build a system that will reproduce the features of the quantum system you want to study,” he said. “Maybe it’s somewhat programmable in that you have some knobs you twist to adjust the parameters, but it’s still mocking up a system rather than providing the complete flexibility of a full digital computer.”

Kollár, who is focusing on developing a new kind of superconducting qubit, calls herself “an analog hardware person at heart.”

“With a digital quantum computer, the goal is complete control, and the qubit does exactly what you want,” she said. “A quantum simulator is much more about letting nature run its course and figuring out what it’s doing—but trying to find an interesting course.”

Even a modest knob-twisting simulator, Childs points out, is still a quantum processor, even if it’s not what he envisions in his theoretical work on algorithms for ideal systems. “For now, it’s an accessible way to move forward … and at the same time, understand some of the big-picture questions.”