Separability does not certify zero-noise extrapolation: Factorial diagnostics in dynamic quantum circuits
Abstract
Separately amplifying gate, latency, and mid-circuit measurement errors can simplify zero-noise extrapolation, but a weak interaction between amplification knobs does not establish an accurate zero-noise limit. We distinguish observable separability, response-model adequacy, and calibration of that limit, and test them in a pre-specified 23 factorial experiment on three IBM dynamic circuits. For the primary echoed spectator observable, the latency-measurement coefficient is bLM=+0.0007 with a nominal 95% bootstrap interval [−0.0033,+0.0049]. A separately planned follow-up meets a ±0.005 equivalence criterion and recovers two injected interactions; both repeat runs nevertheless trigger the drift rule. Multi-knob extrapolations have smaller median absolute errors than the single-knob comparisons, yet all five original strategies exclude the known ideal value for three of six observables. Duration controls support a model-dependent contribution to the spectator deficit from unequal decay rates in native padding and added delay. We give an explicit construction showing why measurements at two measurement-knob levels cannot identify the extrapolated limit without response assumptions. A post-hoc precision analysis and an additive full-factorial estimator expose a further bias-variance trade-off hidden by point-error comparisons. The experiment provides a diagnostic of the implemented response surface, not a certification of physical channel independence or mitigation accuracy.
Related
BibTeX
@misc{kumar2026separability,
title = {{Separability does not certify zero-noise extrapolation: Factorial diagnostics in dynamic quantum circuits}},
author = {Aryan Kumar},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.28705},
eprint = {2610.28705},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.28705},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Separability does not certify zero-noise extrapolation: Factorial diagnostics in dynamic quantum circuits
AU - Aryan Kumar
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.28705
UR - https://arxiv.org/abs/2610.28705
AB - Separately amplifying gate, latency, and mid-circuit measurement errors can simplify zero-noise extrapolation, but a weak interaction between amplification knobs does not establish an accurate zero-noise limit. We distinguish observable separability, response-model adequacy, and calibration of that limit, and test them in a pre-specified 2^3 factorial experiment on three IBM dynamic circuits. For the primary echoed spectator observable, the latency-measurement coefficient is b_LM=+0.0007 with a nominal 95% bootstrap interval [−0.0033,+0.0049]. A separately planned follow-up meets a ±0.005 equivalence criterion and recovers two injected interactions; both repeat runs nevertheless trigger the drift rule. Multi-knob extrapolations have smaller median absolute errors than the single-knob comparisons, yet all five original strategies exclude the known ideal value for three of six observables. Duration controls support a model-dependent contribution to the spectator deficit from unequal decay rates in native padding and added delay. We give an explicit construction showing why measurements at two measurement-knob levels cannot identify the extrapolated limit without response assumptions. A post-hoc precision analysis and an additive full-factorial estimator expose a further bias-variance trade-off hidden by point-error comparisons. The experiment provides a diagnostic of the implemented response surface, not a certification of physical channel independence or mitigation accuracy.
ER -