Spectral Detection of Correlated Errors on Superconducting Quantum Hardware via Parity-Circuit Canaries

Abstract

Version 7 - revised and extended technical preprint.This record contains Version 7 of Spectral Detection of Correlated Errors on Superconducting Quantum Hardware via Parity-Circuit Canaries.The manuscript studies pairwise excess joint-error probabilities using lightweight parity-circuit canaries executed on IBM Quantum superconducting hardware. The direct hardware experiments report statistically significant deviations from a pairwise-independence null in the tested two-qubit canary circuits. The work further examines controls for isolated readout, simultaneous single-qubit control pulses, measurement batching, repeated entangling operations, parameterized controlled rotations, and candidate mechanisms associated with the implementation of two-qubit gates Version 7 revises the interpretation of earlier versions while preserving the underlying reported measurements. In particular, the eigenvalue-based violation score is treated as a normalization-dependent, exploratory summary statistic rather than a definitive calibration-free test. The primary evidentiary quantity is the measured excess joint-error probability relative to a pairwise-independence null. The parameterized CRY sweep is interpreted as a dependence on rotation angle and compiled gate implementation; for the computational-basis preparation used in that sweep, it does not itself demonstrate a dependence on generated entanglement. Spatial and cross-device interpretations obtained before explicit physical-layout verification are retained with an explicit provisional qualification.The record is part of a versioned public research history. Earlier versions document the development of the hypothesis and analysis; this version provides the current corrected technical interpretation of the reported IBM hardware results. The file in this record is the manuscript PDF. Raw job data and analysis scripts are not included in this deposit.