Quantum volume per Cross et al. 2019: finite-shot heavy outputs, the 2-sigma pass rule, per-width intervals, achieved QV and a report.
Officially provided by KetQat — method by Cross et al. (2019), Aaronson and Chen (2017) and others. KetQat prepares, verifies and maintains this product; it does not claim to have invented the method. Read the origin statement.
Runs the quantum volume protocol of Cross, Bishop, Sheldon, Nation and Gambetta (2019) on a simulated device over a list of widths. For every width it draws the square model circuits of Haar-random SU(4) layers (the open SDK's circuits and ideal distributions), mixes each ideal output distribution toward uniform with the depolarizing rate, samples a finite number of shots per circuit and counts heavy outcomes, those above the ideal median. The certification applies the protocol's rule exactly: the mean heavy-output probability over circuits must exceed 2/3 by two binomial standard deviations, h - 2 sqrt(h(1-h)/n_c) > 2/3. Beside that rule it reports a 95% interval from the empirical spread across circuits and a bootstrap interval, the mean ideal and exact noisy heavy-output probabilities for reference, the achieved quantum volume 2^(largest passing width) with a flag saying whether every smaller tested width also passes, whether the circuit count meets the protocol's minimum of 100, and a Markdown report.
For people who want the certification rule applied as published, with its statistics visible, as a reference for a device run or for teaching.
This is a KetQat Pro product: it runs locally like every catalog product, from a signed bundle installed with ketqat pro install under a time-limited entitlement. Its implementation is not part of the open SDK.
Installs the KetQat SDK from commit 2cedabbd814f, the exact version whose product definition this page shows. The SDK is not on PyPI yet, so pip install ketqat alone will not work.
pip install "ketqat[pro,qinfo] @ git+https://github.com/ketqat/ketqat-sdk@2cedabbd814fd199b1989c8ceb1e9efa1744c2c0#subdirectory=python" && ketqat pro login && ketqat pro install [email protected]Save it as example.py and run python example.py. Or use the CLI: ketqat catalog run [email protected].
import json
from ketqat_runner import catalog
record = catalog.run("[email protected]", seed=2026, widths=[2, 3], circuits_per_width=100, shots=500, depolarizing_rate=0.05)
result = record.result
print(json.dumps({
"status": record.status,
"achieved_quantum_volume": result["achieved_quantum_volume"],
"all_smaller_widths_pass": result["certification"]["all_smaller_widths_pass"],
"every_width_above_two_thirds": all(w["certification"]["heavy_output_probability"] > 2 / 3 for w in result["per_width"]),
}))
{
"status": "succeeded",
"achieved_quantum_volume": 8,
"all_smaller_widths_pass": true,
"every_width_above_two_thirds": true
}Verified with
No verification run of this example is recorded in its definition. Pro examples need an entitlement, which the public SDK CI does not have.
ketqat report RUN_ID sends an opt-in usage report: product, version, succeeded/failed, time and SDK version only. It shows you the exact payload first and needs an API token from Settings. Nothing is sent unless you run it.
This is a Pro product
The open SDK already builds quantum volume model circuits with Haar-random SU(4), computes their exact ideal and depolarized heavy-output probabilities and, at one width, applies a 2-sigma bound from the empirical spread across circuits (quantum_volume.py). Nothing of that moves behind Pro, and this product calls those functions. Pro adds the certification as one catalog run: finite-shot sampling of heavy outcomes per circuit, the protocol's binomial 2-sigma rule as published, empirical and bootstrap intervals beside it, several widths with the achieved quantum volume and a monotonicity flag, the circuit-count minimum check, and a Markdown report.
ketqat pro loginketqat pro install [email protected]ketqat catalog run [email protected]ketqat pro login stores a signed entitlement valid for up to 7 days; runs start offline while it is valid. Cancelling stops new Pro runs and updates after it expires. Your results are never deleted, and Free products are unaffected. This is not DRM.
| Name | Type | Default | Allowed values | Description |
|---|---|---|---|---|
| widths | integer[] | [2,3,4] | maxItems: 6; minItems: 1; itemMaximum: 12; itemMinimum: 2; uniqueItems: true | Circuit widths m (and depths, since the model circuits are square), distinct. |
| circuits_per_width | integer | 100 | maximum: 2000; minimum: 2 | Random model circuits per width; the protocol runs at least 100. |
| shots | integer | 500 | maximum: 100000; minimum: 1 | Measurements sampled per circuit. |
| depolarizing_rate | number | 0.05 | maximum: 1; minimum: 0 | Weight with which each circuit's ideal output distribution is mixed toward uniform (global depolarizing); 1 is a fully depolarized device. |
| Name | Type | Description |
|---|---|---|
| achieved_quantum_volume | integer | 2^(largest tested width that passes the rule); null when no tested width passes. |
| certification | object | passing_widths, failing_widths, max_passing_width, all_smaller_widths_pass, tested_widths and an interpretation sentence. |
| per_width | object[] | Per width: the rule's heavy_output_probability, binomial sigma, two_sigma_lower_bound and passed; empirical and bootstrap 95% intervals; mean ideal and exact noisy heavy-output probabilities; per-circuit heavy counts and seeds. |
| meets_protocol_minimum_circuits | boolean | true when circuits_per_width is at least 100. |
| report | string | Markdown report with the per-width table, the achieved quantum volume and caveats. |
Not generated in the open SDK: running this product needs a Pro entitlement and bundle, which this repository's CI does not have. Maintainer run of the private bundle with the defaults (widths 2, 3, 4; 100 circuits; 500 shots; depolarizing rate 0.05; seed 2026): heavy-output probabilities 0.7638, 0.8373 and 0.8254 with rule lower bounds 0.6789, 0.7635 and 0.7494, all passing; achieved quantum volume 16 with every smaller width passing; mean ideal heavy-output probabilities 0.7792, 0.8546 and 0.8408 (the asymptote (1 + ln 2)/2 = 0.8466 is not reached at width 2). At depolarizing rate 0.1 on the same seed width 2 fails marginally (bound 0.6641) while 3 and 4 pass, and the result says so.
No validation tests are recorded for this product
Read the limitations above before relying on its results.1.0.01 Nov 2026currentShown on this page
Needs SDK 0.3.0 or later with extras: pro, qinfo.
KetQat implementation of published methods
Quantum volume, its model circuits and its pass rule are due to Cross, Bishop, Sheldon, Nation and Gambetta (2019); heavy-output generation follows Aaronson and Chen (2017); Haar-random unitaries are drawn by the QR method of Mezzadri (2007). The circuits and ideal distributions come from the open SDK's quantum_volume.py, and the sampling and statistics use NumPy. KetQat wrote the certification workflow: finite-shot heavy counts, the rule and intervals, the multi-width aggregation, the report and this catalog entry. KetQat did not invent the protocol or the rule.
LicenseRef-KetQat-Pro — the KetQat Pro license. See Licensing.
People credited for this product. KetQat publishes and maintains it; contributors are credited for their work and are not sellers.
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Computed 10 Nov 2026, 17:34 UTC.
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