Researchers at the University of Chicago's Pritzker School of Molecular Engineering have developed a new design for a superconducting quantum processor. The team, from the Cleland Lab, has introduced a modular quantum processor with a reconfigurable router as its central hub. This innovative approach allows any two qubits to connect and entangle, unlike previous designs where qubits could only interact with their nearest neighbors.

Ph.D. student Xuntao Wu explained, "Imagine you have a classical computer that has a motherboard integrating lots of different components, like your CPU or GPU, memory and other elements. Part of our goal is to transfer this concept to the quantum realm." Wu is the lead author of a paper published in Physical Review X detailing this novel method for connecting superconducting qubits.

The new chip is described as flexible and scalable, akin to chips used in cellphones and laptops. According to Prof. Andrew Cleland, "This scaling can offer solutions to computational problems that a classical computer simply cannot hope to solve, like factoring huge numbers and thereby cracking encryption codes."

Traditional designs face limitations due to their structure; each qubit on a grid can only connect with up to four neighbors. Co-author Haoxiong Yan noted that this layout poses challenges: "To undertake practical quantum computing, we need millions or even billions of qubits and we need to make everything perfectly."

The team's design draws inspiration from classical computers by clustering qubits around a central router. Quantum switches allow rapid connections within nanoseconds, enabling high-fidelity quantum gates and generating quantum entanglement.

Wu stated that there is theoretically no limit to the number of qubits that can be connected via routers: "You can connect more qubits if you want more processing power, as long as they fit in a certain footprint." Future work will focus on scaling up the processor's capabilities and exploring ways to link remote qubits.

"Right now, the coupling range is sort of medium-range," said Wu. "So if we're trying to think of ways to connect remote qubits, then we must explore new ways to integrate other kinds of technologies with our current setup."

The research was supported by funding from the Army Research Office and Laboratory for Physical Sciences and the Air Force Office of Scientific Research.

Citation: “Modular Quantum Processor with an All-to-All Reconfigurable Router,” Wu et al., Physical Review X, November 4, 2024.

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