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Abstract: Quantum error correction provides a path toward scalable quantum computing with the construction of large arrays of qubits. However, the promised exponential suppression of logical error rests on the assumption that the physical errors in these devices are both small and sufficiently uncorrelated. Impacts from high energy radiation violate these assumptions.
Impinging particles ionizes the substrate, radiating high energy phonons that induce a burst of quasiparticles that severely limits qubit coherence throughout the device. While such impact events are already well studied in detectors for high-energy physics and astronomy, they have not yet been identified in qubit arrays or had their effect on error correction quantified.
In this talk, we identify radiation impact events in large quantum processors designed for error correction. We find impacts produce large bursts of correlated error that last for thousands of error correction cycles, preventing any attempt at correction. We track the events from their initial localised impact to high error rates across the chip, and quantify the effect of the resulting quasiparticle densities on qubit coherence times. Finally, we consider strategies to mitigate these impact events with a view to enable future quantum error correction experiments.