Corpus & leaderboard

Beyond your own runs, QuantumLedger maintains a public calibration corpus: a cross-vendor, longitudinal record of how real quantum hardware behaves over time. It powers the State of Quantum Hardware leaderboard at /leaderboard.

The corpus

The corpus is a collection of calibration snapshots normalized to the open qlprov/calibration/1.0 schema, so an IBM device and an IonQ device can be compared on the same axes. Snapshots are content-addressed, so identical captures are stored once and referenced many times.

The crawler

The quantumledger-crawler package collects vendor calibration data, normalizes it, applies each vendor's terms-of-service redistribution policy, deduplicates, and ingests it into the corpus. It has two sources:

• FixtureSource (default, offline) — reads representative payloads from fixtures/{vendor}/*.json. This is what the demo and tests use; no network required.
• LiveSource (optional) — a skeleton for calling real vendor APIs (IBM BackendProperties, IonQ characterization, Amazon Braket device properties).

A ToS gate governs what may be redistributed, so the public corpus respects each vendor's terms.

The leaderboard

/leaderboard ranks devices across vendors by calibration quality. You can switch the ranking metric:

• median two-qubit gate error,
• T1 / T2 coherence times,
• readout fidelity.

Because snapshots are time-stamped, the corpus also exposes trends per device:

GET /api/v1/backends/<provider>/<backend_id>/trend

— a time series of a backend's calibration quality, so you can see a device improving or degrading over weeks and months.

Why it exists

The corpus turns one-off calibration captures into a shared, comparable, historical view of the quantum hardware fleet — the empirical backdrop against which your own runs and reproductions can be judged.

Next: Product tour.