<p>Quantum information processing at scale will require sufficiently stable and long-lived qubits, likely enabled by error-correction codes. Several recent superconducting-qubit experiments, however, reported observing intermittent spatiotemporally correlated errors that would be problematic for conventional codes, with ionizing radiation being a likely cause. Here, we directly measured the cosmic-ray contribution to spatiotemporally correlated qubit errors. We accomplished this by synchronously monitoring cosmic-ray detectors and qubit energy-relaxation dynamics of 10 transmon qubits distributed across a 5 × 5 × 0.35 mm<sup>3</sup> silicon chip. Cosmic rays caused correlated errors at a rate of <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41467_2025_61385_Article_IEq1.gif" Format="GIF" Height="43" Rendition="HTML" Resolution="72" Type="Linedraw" Width="118" /> </InlineMediaObject> <EquationSource Format="TEX">$1/\left(592\begin{array}{c}+48\\ -41\end{array}\,{\rm{s}}\right)$</EquationSource> <EquationSource Format="MATHML"><math> <mn>1</mn> <mo>/</mo> <mfenced close=")" open="("> <mrow> <mn>592</mn> <mtable> <mtr> <mtd columnalign="center"> <mo>+</mo> <mn>48</mn> </mtd> </mtr> <mtr> <mtd columnalign="center"> <mo>−</mo> <mn>41</mn> </mtd> </mtr> </mtable> <mspace width="0.25em" /> <mi mathvariant="normal">s</mi> </mrow> </mfenced> </math></EquationSource> </InlineEquation>, accounting for 17.1 ± 1.3% of all such events. Our qubits responded to essentially all of the cosmic rays and their secondary particles incident on the chip, consistent with the independently measured arrival flux. Moreover, we observed that the landscape of the superconducting gap in proximity to the Josephson junctions dramatically impacts the qubit response to cosmic rays. Given the practical difficulties associated with shielding cosmic rays, our results indicate the importance of radiation hardening—for example, superconducting gap engineering—to the realization of robust quantum error correction.</p>

Synchronous detection of cosmic rays and correlated errors in superconducting qubit arrays

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2025年7月11日

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Patrick M. Harrington,
Mingyu Li,
Max Hays,
Wouter Van De Pontseele,
Daniel Mayer,
H. Douglas Pinckney,
Felipe Contipelli,
Michael Gingras,
Bethany M. Niedzielski,
Hannah Stickler,
Jonilyn L. Yoder,
Mollie E. Schwartz,
Jeffrey A. Grover,
Kyle Serniak,
William D. Oliver,
Joseph A. Formaggio

摘要

Quantum information processing at scale will require sufficiently stable and long-lived qubits, likely enabled by error-correction codes. Several recent superconducting-qubit experiments, however, reported observing intermittent spatiotemporally correlated errors that would be problematic for conventional codes, with ionizing radiation being a likely cause. Here, we directly measured the cosmic-ray contribution to spatiotemporally correlated qubit errors. We accomplished this by synchronously monitoring cosmic-ray detectors and qubit energy-relaxation dynamics of 10 transmon qubits distributed across a 5 × 5 × 0.35 mm³ silicon chip. Cosmic rays caused correlated errors at a rate of $1/\left(592\begin{array}{c}+48\\ -41\end{array}\,{\rm{s}}\right)$ $1 / (592 \begin{matrix} + 48 \\ - 41 \end{matrix} s)$ , accounting for 17.1 ± 1.3% of all such events. Our qubits responded to essentially all of the cosmic rays and their secondary particles incident on the chip, consistent with the independently measured arrival flux. Moreover, we observed that the landscape of the superconducting gap in proximity to the Josephson junctions dramatically impacts the qubit response to cosmic rays. Given the practical difficulties associated with shielding cosmic rays, our results indicate the importance of radiation hardening—for example, superconducting gap engineering—to the realization of robust quantum error correction.