The Rotation Gap Is Not An Error: Ternary Structure in IBM Quantum Hardware

• URL: http://arxiv.org/abs/2604.11963v1
• Date: Mon, 13 Apr 2026 18:54:39 GMT
• Title: The Rotation Gap Is Not An Error: Ternary Structure in IBM Quantum Hardware
• Abstract summary: Quantum error correction assumes that all syndrome activations represent errors requiring correction.<n>We present evidence from 756 QEC runs across three IBM Eagle r3 processors that this assumption is wrong.<n> Hardware exhibits sub-Poissonian syndrome statistics, indicating that a fraction of syndrome events are not random noise but structured cooperative transitions.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Quantum error correction assumes that all syndrome activations represent errors requiring correction. We present evidence from 756 QEC runs across three IBM Eagle r3 processors that this assumption is wrong. The hardware exhibits sub-Poissonian syndrome statistics (Fano factor F = 0.856, t = -131 against Poisson, zero dependence on code distance), indicating that a fraction of syndrome events are not random noise but structured cooperative transitions. We introduce a regime classifier decoder that distinguishes binary errors (which should be corrected) from ternary transitions (which should not). On a mixed binary/ternary error model calibrated to IBM hardware statistics, the classifier reduces logical error rates by 7-19% at static detection depth (tau = 1) across all cell sizes, with statistical significance p < 0.05 in 7 of 8 test conditions (p < 0.0001 in all four tau = 1 conditions). The improvement mechanism is selective abstention: the classifier correctly identifies 75-98% of ternary transitions and leaves them uncorrected (75-81% at tau = 1, 88-98% at tau = 5), whereas a standard decoder miscorrects them, introducing errors that would not otherwise exist. A cross-platform control on Google's 105-qubit Willow processor (420 experiments, d = 3, 5, 7) shows the opposite: super-Poissonian statistics (F = 2.42), super-linear burst scaling, and positive spatial correlation -- confirming that the sub-Poissonian signal is absent from standard surface-code circuits that lack the P-gate asymmetry. The result demonstrates that standard QEC actively destroys quantum information by correcting valid ternary states, and that less correction produces better performance when the hardware has cooperative error structure.

Related papers

• Absent, Not Faint: Fisher-Information Limits and a Logarithmic Measurement-Design Cure for Passive Characterization of Coherent Qubit Noise [18.420138629160196]
  A coherent over-rotation is a small systematic gate miscalibration.<n>A fixed, logarithmically small set of extra settings makes every such fault visible.<n>We prove the impossibility and cure, confirm both in exact simulation, and observe a 3-5x bias gap on IBM Heron hardware as a consistency check.
  arXiv  Detail & Related papers  (2026-07-23T00:46:29Z)
• Amplifying, Not Learning: Fine-Tuned AI Text Detectors Amplify a Pretrained Direction [51.56484100374058]
  Text detectors amplify a pretrained typicality axis; they do not construct an AI-vs-human boundary.<n>On raw encoders before any task supervision, projecting onto centroid(AI)-centroid(HC3) achieves NYT-vs-HC3 AUROC 0.806/0.944/0.834 across three architectures.<n>On RoBERTa-base, raw projection exceeds fine-tuning; on RoBERTa-base, full fine-tuning reduces discrimination below raw on both fluent-formal populations tested.
  arXiv  Detail & Related papers  (2026-05-20T19:08:38Z)
• Decodable but Not Corrected by Fixed Residual-Stream Linear Steering: Evidence from Medical LLM Failure Regimes [4.738949927143789]
  We investigate whether linearly decodable failure signals in hidden states can be leveraged to correct those failures.<n>We find that decodable failure structure supports post-generation reliability estimation even when the fixed linear steering family cannot exploit it for correction.
  arXiv  Detail & Related papers  (2026-05-07T05:58:38Z)
• ERRORQUAKE: Heavy-Tailed Error Severity Distributions in Open-Weight Large Language Models [0.0]
  Hallucination benchmarks report a single error count and treat all errors as equivalent, yet a wrong date and a fabricated court ruling differ by orders of magnitude.<n>We introduce Errorquake-10k, a benchmark scoring each response on a continuous 0-4 severity scale across 8 domains and 5 difficulty tiers.
  arXiv  Detail & Related papers  (2026-04-15T09:22:46Z)
• The Verification Tax: Fundamental Limits of AI Auditing in the Rare-Error Regime [0.0]
  Most cited calibration result in deep learning -- post-temperature-scaling ECE of 0.012 on CIFAR-100 -- is below the statistical noise floor.<n>We prove this is not a failure of the experiment but a law: the minimax rate for estimating calibration error with model error rate epsilon is Theta((Lepsilon/m)2/3), and no estimator can beat it.
  arXiv  Detail & Related papers  (2026-04-14T16:48:24Z)
• PAEMS: Precise and Adaptive Error Model for Superconducting Quantum Processors [6.599826548609388]
  This paper introduces PAEMS: a precise and adaptive qubit error model.<n> Experiments on IBM's QPUs have demonstrated a 19.5$times$, 9.3$times$, and 5.2$times$ reduction in timelike, spacelike, and spacetime error correlation.<n>It also outperforms the accuracy of Google's SI$71000 error model by 58$sim3% on multiple quantum platforms.
  arXiv  Detail & Related papers  (2026-03-31T08:46:18Z)
• A biased-erasure cavity qubit with hardware-efficient quantum error detection [19.031335768368475]
  Erasure qubits are beneficial for quantum error correction due to their relaxed threshold requirements.<n>We realize a hardware-efficient biased-erasure qubit encoded in the vacuum and two-photon Fock states of a single microwave cavity.
  arXiv  Detail & Related papers  (2026-01-29T12:19:59Z)
• Demonstrating dynamic surface codes [118.67046728951689]
  We experimentally demonstrate three time-dynamic implementations of the surface code.<n>First, we embed the surface code on a hexagonal lattice, reducing the necessary couplings per qubit from four to three.<n>Second, we walk a surface code, swapping the role of data and measure qubits each round, achieving error correction with built-in removal of accumulated non-computational errors.<n>Third, we realize the surface code using iSWAP gates instead of the traditional CNOT, extending the set of viable gates for error correction without additional overhead.
  arXiv  Detail & Related papers  (2024-12-18T21:56:50Z)
• Scaling and logic in the color code on a superconducting quantum processor [109.61104855764401]
  We present a demonstration of the color code on a superconducting processor, achieving logical error suppression and performing logical operations.<n>We inject magic states, a key resource for universal computation, achieving fidelities exceeding 99% with post-selection.<n>This work establishes the color code as a compelling research direction to realize fault-tolerant quantum computation on superconducting processors.
  arXiv  Detail & Related papers  (2024-12-18T19:00:05Z)
• Error mitigation, optimization, and extrapolation on a trapped ion testbed [0.05185707610786576]
  A form of error mitigation called zero noise extrapolation (ZNE) can decrease an algorithm's sensitivity to these errors without increasing the number of required qubits. We explore different methods for integrating this error mitigation technique into the Variational Quantum Eigensolver (VQE) algorithm. Our results show that the efficacy of this error mitigation technique depends on choosing the correct implementation for a given device architecture.
  arXiv  Detail & Related papers  (2023-07-13T19:02:39Z)
• Witnessing entanglement in trapped-ion quantum error correction under realistic noise [41.94295877935867]
  Quantum Error Correction (QEC) exploits redundancy by encoding logical information into multiple physical qubits. We present a detailed microscopic error model to estimate the average gate infidelity of two-qubit light-shift gates used in trapped-ion platforms. We then apply this realistic error model to quantify the multipartite entanglement generated by circuits that act as QEC building blocks.
  arXiv  Detail & Related papers  (2022-12-14T20:00:36Z)
• Validation tests of GBS quantum computers give evidence for quantum advantage with a decoherent target [62.997667081978825]
  We use positive-P phase-space simulations of grouped count probabilities as a fingerprint for verifying multi-mode data. We show how one can disprove faked data, and apply this to a classical count algorithm.
  arXiv  Detail & Related papers  (2022-11-07T12:00:45Z)
• Fault-tolerant parity readout on a shuttling-based trapped-ion quantum computer [64.47265213752996]
  We experimentally demonstrate a fault-tolerant weight-4 parity check measurement scheme. We achieve a flag-conditioned parity measurement single-shot fidelity of 93.2(2)%. The scheme is an essential building block in a broad class of stabilizer quantum error correction protocols.
  arXiv  Detail & Related papers  (2021-07-13T20:08:04Z)
• Exponential suppression of bit or phase flip errors with repetitive error correction [56.362599585843085]
  State-of-the-art quantum platforms typically have physical error rates near $10-3$. Quantum error correction (QEC) promises to bridge this divide by distributing quantum logical information across many physical qubits. We implement 1D repetition codes embedded in a 2D grid of superconducting qubits which demonstrate exponential suppression of bit or phase-flip errors.
  arXiv  Detail & Related papers  (2021-02-11T17:11:20Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.