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arXiv · 2110.04285

Calibrated decoders for experimental quantum error correction

Edward H. Chen·Theodore J. Yoder·Youngseok Kim·Neereja Sundaresan·Srikanth Srinivasan·Muyuan Li·Antonio D. Córcoles·Andrew W. Cross·Maika Takita
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Abstract

Arbitrarily long quantum computations require quantum memories that can be repeatedly measured without being corrupted. Here, we preserve the state of a quantum memory, notably with the additional use of flagged error events. All error events were extracted using fast, mid-circuit measurements and resets of the physical qubits. Among the error decoders we considered, we introduce a perfect matching decoder that was calibrated from measurements containing up to size-4 correlated events. To compare the decoders, we used a partial post-selection scheme shown to retain ten times more data than full post-selection. We observed logical errors per round of $2.2\pm0.1\times10^{-2}$ (decoded without post-selection) and $5.1\pm0.7\times10^{-4}$ (full post-selection), which was less than the physical measurement error of $7\times10^{-3}$ and therefore surpasses a pseudo-threshold for repeated logical measurements.

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Edward H. Chen, Theodore J. Yoder, Youngseok Kim, Neereja Sundaresan, Srikanth Srinivasan, Muyuan Li, Antonio D. Córcoles, Andrew W. Cross, Maika Takita. 2021-10-08. Calibrated decoders for experimental quantum error correction. https://doi.org/10.1103/physrevlett.128.110504

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