Completing or Refusing Low-Dimensional Records of Structured Quantum Circuits: Measurement Loss, Compression Loss, and Hardware Drift

Abstract

Structured quantum circuits are often represented by low-dimensional records such as occupation numbers or constraint feasibility rather than by full outcome distributions. A record loses control-dependent information when it merges outcomes whose probabilities respond differently to circuit parameters. We assess this loss without assuming a parametric hardware-noise model. Quantum Fisher information bounds premeasurement sensitivity; Fisher metrics of measurements and recorded statistics describe device-attainable sensitivity. For finite control changes, a Hellinger residual measures the response removed by a record, while its local quadratic term is the conditional covariance of the full-outcome score. Simultaneous confidence bounds support approval, refusal, or deferral. We prove a finite-library completion theorem: executable augmentations terminate either with a record preserving every declared response or with proof that no library augmentation removes the loss. For an analytic control germ, integral closures characterize preservation along every analytic control arc, and finitely many Rees valuations detect failure. This connects the state--measurement--record chain to an executable completion-or-refusal procedure, an attainable-Fisher kernel criterion, and finite-sample decisions. A three-qubit calculation separates measurement loss from record loss. Prospectively fixed IBM Kingston and Marrakesh experiments test decisions in four-qubit fixed-particle-number and GHZ families, including negative controls. In two-epoch IQM Garnet data, median record-level drift is 0.0797 times full-distribution drift, but a significant residual remains in 35 of 36 settings. On these circuits, the rules detect loss and approve records only within stated tolerances; they do not establish universal compression performance or device quantum Fisher information.