Rutgers and IBM researchers show a 156-qubit quantum processor can correct itself while running
Researchers from Rutgers, IBM and collaborating institutions reported in Nature Physics that a quantum computer can repeatedly check and reset its qubits while it runs, bringing chaotic behaviour under control. The experiment ran on an IBM Quantum Heron processor with 156 qubits, using a connected chain of up to 100, and the team performed nearly 5,000 two-qubit operations and nearly 5,000 checks and resets. The researchers describe it as one of the largest demonstrations of real-time quantum feedback control to date, though no fault-tolerant quantum computer yet exists.
Bottom line — Real-time error control on 100 qubits is a step toward fault-tolerant machines, but Pixley says many more checks and corrections will be needed.
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Jedediah Pixley of Rutgers said a fault-tolerant machine would need these checks and corrections a huge number of times during a calculation, calling the experiment a landmark on that road.
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Maika Takita of IBM said the difficulty was measuring a qubit repeatedly while the rest of the processor kept operating, and that the work shows present-day hardware can coordinate operations, measurements and resets thousands of times.
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Quantum information cannot simply be copied, and measuring it can change or destroy the state, so error correction must work without losing the information being protected, according to the Mirage News and bioengineer.org accounts.
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The team tested a theory on systems of up to 100 qubits, far beyond the roughly two dozen that can be simulated on conventional computers, and Haining Pan of Rutgers said the results closely matched predictions.
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The project began as a 2021 party wager, which Sriram Ganeshan won and Pixley paid off in blueberry ice cream, according to the Rutgers release reproduced by Mirage News and BrightSurf.