We present QEU-Diagnostic, the world's first system for simultaneous parallel T1/T2 measurement and automated qubit quality grading. Experimental validation was performed on IBM ibm_torino (156 qubits). The system grades qubits from PERFECT to WTF based on delta-psi peak analysis. Patent: KR 10-2025-0180416Contact: jgch1234@icloud.com
We present QEU-Diagnostic, the world's first system for simultaneous parallel T1/T2 measurement and automated qubit quality grading. Experimental validation was performed on IBM ibm_torino (156 qubits). The system grades qubits from PERFECT to WTF based on delta-psi peak analysis. Patent: KR 10-2025-0180416Contact: jgch1234@icloud.com
We report the first experimental validation of a scalable, non-invasive quantum processor diagnostic system at 64-qubit scale. The TRUE Zigzag protocol characterizes T1 and T2 coherence properties of all target qubits simultaneously within a single job execution, producing a complete qubit health map from only three job submissions. Tested on IBM Quantum's ibm_fez backend (8,192 shots), the system graded all 64 qubits from EXCELLENT to UNSTABLE with baseline-to-after stability of 0.985→0.985, confirming non-invasive operation. Central discovery — Decreasing Scaling Law: Average diagnostic disturbance measured 0.252% at 8 qubits, 0.146% at 32 qubits, and 0.148% at 64 qubits, representing 92.7% improvement over linear scaling predictions. The 64Q/32Q ratio of 1.01× demonstrates plateau behavior, indicating no accuracy loss at arbitrarily larger scales. All three IBM Quantum Job IDs are publicly disclosed for independent verification. Full per-qubit data (CSV), experimental metadata (JSON), and visualization (PNG) are included. Patent: KR 10-2025-0180416
Abstract We introduce Quantum Diagnostic Intelligence (QDI), a five-layer decision-support architecture for inferring the operational state of quantum processing units from circuit-level measurements. Pulse-level calibration metrics — coherence times T₁ and T₂ measured through single-qubit Rabi and Ramsey sequences — are the dominant industry standard for certifying quantum hardware health. We demonstrate, through 191 circuit executions on three 156-qubit IBM Heron r2 processors, that circuit-level measurements contain diagnostic information that T₁/T₂ may not capture. On ibm_marrakesh between July 3 and July 5, 2026, IBM-reported T₂ improved from 303 to 340 µs (+ 12%), while circuit-level GHZ scaling yielded α = 3.811, a QDI health score of 37.8/100 [95% CI: 7.6, 67.9], and a circuit infidelity increase of 920% at n = 2 qubits. The QDI architecture formalizes this observation through four operators: a diagnostic state classifier D(χ), a health score H(χ), a recommendation generator R(χ), and a drift forecast F(χ, t). Rules trained on ibm_kingston correctly classified ibm_fez and both ibm_marrakesh sessions without retuning (3/3 held-out tests; n = 4 total — feasibility demonstration only). We identify three scientific limitations of the current framework: operators rely on expert-designed rules rather than learned statistical models; ground truth (algorithm success/failure) has not yet been collected; and diagnostic state labels have not been validated by clustering analysis. Prospective validation on n ≥ 50 independent sessions is required before statistical claims about generalization can be made. The dataset, code, and QDI system are openly available.
This publication presents a straightforward experimental study measuring the energy-relaxation time, or T1, of a superconducting qubit on IBM Quantum hardware. It explains the basic idea behind the test, preparing the qubit in the excited state, letting it sit for different delay times, and measuring how quickly it decays back toward the ground state, then fits the results to an exponential decay model that accounts for measurement imperfections. Using the ibm_torino backend on qubit Q0, the paper reports a measured T1 of about 132 microseconds, based on a single sweep of 25 delay values with 4096 shots per point. Along with the result, the publication includes the theoretical model, experimental setup, raw decay data, and discussion of limitations such as noise, drift, and fit-quality concerns, making it both a concise report of the measurement and a reproducible example for readers interested in quantum hardware characterization.
Pulse-level calibration metrics — coherence times T₁ and T₂ measured through single-qubit Rabi and Ramsey sequences — are the standard by which quantum hardware providers certify device health. We demonstrate, through 191 circuit executions on three 156-qubit IBM Heron r2 processors (ibm_kingston, ibm_fez, and ibm_marrakesh), that these pulse-level metrics can give opposite conclusions to circuit-level diagnostics on the same device at the same time. Specifically, between experimental sessions on July 3 and July 5, 2026, IBM reported ibm_marrakesh T₂ improved from 303 μs to 340 μs (a 12% improvement), while the K–R scaling exponent α measured from GHZ circuit scaling increased from 1.406 to 3.811 (a 171% increase in coherent error dominance) and GHZ n=2 infidelity rose from 0.018 to 0.204 — a 920% increase in circuit error. We further demonstrate that Ramsey circuit-context T₂ on qubit 0 is approximately 9–30 μs, compared to IBM-reported pulse-level T₂ of 32–340 μs — a discrepancy of 3–11×. We introduce five experimental demonstrations showing K–R circuit-level diagnostics detect degradation invisible to T₁/T₂, provide higher temporal sensitivity, enable algorithm failure prediction, and confirm the theoretical prediction αₜᵥₜᶜʰ + αₑₜₕₒ = 2 within 7% on real hardware. These findings establish circuit-level K–R diagnostics as a necessary complement to pulse-level calibration for operational quantum computing.
Abstract An efficient characterization of QND measurements is an important ingredient toward certifying and improving the performance and scalability of quantum processors. In this work, we introduce a parallel tomography of QND measurements that addresses single- and two-qubit readout on a multi-qubit quantum processor. We provide an experimental demonstration of the tomographic protocol on a 7-qubit IBM-Q device, characterizing the quality of conventional qubit readout as well as generalized measurements such as parity or measurement-and-reset schemes. Our protocol reconstructs the Choi matrices of the measurement processes, extracts relevant quantifiers—fidelity, QNDness, destructiveness—and identifies sources of errors that limit the performance of the device for repeated QND measurements. We also show how to quantify measurement crosstalk and use it to certify the quality of simultaneous readout on multiple qubits.