Quantum error correction decoders tested with new validation methods
Capability-Gated Conformance Testing of Quantum Error-Correction Decoder Libraries
Hardware Architecture
Summary
Quantum computers rely on software called decoders to fix errors in their calculations, but checking if these decoders work right is tricky. The authors propose new ways to test decoders that do not need a reference answer and can catch problems that traditional checks miss. They tested several existing decoders and found some rarely reported issues in how corrections are chosen and documented. Their work helps make sure quantum error correction software is more reliable and transparent for users.
quantum error correctiondecodersyndromelogical observableminimum-weight correctionbounded-distance correctnessoracleconformance testingverificationlogical parity
Authors
Jiachen Shen, Hui Zhong
Abstract
A quantum error correction decoder is a library other people's results depend on, judged in one dominant way. Sample errors, decode, and count wrong logical observables. We ask what else can be checked there. Our conformance contract needs no oracle. One check asks that a returned correction explain the syndrome in the caller's index space. The other hands a decoder one instance under two presentations differing only in bookkeeping, where two feasible corrections of different weight prove the heavier is not minimum-weight. Verdicts are gated on what each library declares, so a firing contradicts a published guarantee. Nine configurations from five public libraries give three results. Documentation answers 4 of 54 capability questions. Bounded-distance correctness, the property callers most depend on, has a direct declaration yield of 0.0%, though its hypotheses hold in 62.1% of cases. Presentation sensitivity is real but shallow. One solver moved to a 26% heavier correction under a different numbering, which reaches the logical class at most once in twenty thousand shots. Established evaluation misses corruptions that preserve logical parity, while one summation over the caller's weights catches every one we injected. All 639 certificates ship as bundles a standalone verifier re-derives from first principles.