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Introduction
What is QuantumLedger? Getting started
Concepts & workflows
Core concepts Capturing runs Reproduce & drift Result cards & badges Compliance & attestations Corpus & leaderboard
Using the app
Product tour (every page & button)
Libraries & reference
Libraries & downloads CLI reference API reference Frameworks reference Open schemas (qlprov) Deployment & self-hosting
Introduction

What is QuantumLedger?

QuantumLedger is the vendor-neutral system of record for quantum computing.

A quantum result is only meaningful alongside the exact hardware state that produced it. Devices drift hour to hour, transpilers change circuits, and every vendor reports calibration differently — so a raw bitstring histogram, on its own, is not reproducible, comparable, or auditable. QuantumLedger binds every run to the circuit, backend, and calibration snapshot that produced it, into one immutable, hash-chained record. That record is the "source of truth" that mature software has in every other data-intensive field, applied to the noisy, drifting world of quantum.

If you can't say which device state produced a result, you can't reproduce it, cite it, or attest to it. QuantumLedger makes that state a first-class, tamper-evident part of every result.

The six pillars

QuantumLedger is one product with six connected areas. Each has its own guide:

  1. Capture — a one-line @ql.capture decorator records your job locally, with no account required. → Capturing runs
  2. Provenance store — an immutable, content-addressed, Merkle-hashed ledger of runs. → Core concepts
  3. Reproduce & analyse — re-run a stored circuit against a drifted device state and score how much changed. → Reproduce & drift
  4. Trust artifacts — public, citable Result Cards and embeddable badges. → Result cards & badges
  5. Compliance — pick a standard (FAIR, IEEE P7131, …); evidence is auto-collected from the runs already in the record; issue signed, revocable attestations. → Compliance & attestations
  6. Public corpus — a cross-vendor, longitudinal corpus of calibration data powering the leaderboard. → Corpus & leaderboard

How the pieces fit together

your quantum job
   │  @ql.capture                         (open-source SDK, runs anywhere)
   ▼
local ledger (SQLite, offline)  ──ql push──►  hosted QuantumLedger
   │                                              │
   │ ql reproduce                                 ├─ Records + provenance
   ▼                                              ├─ Reproduce engine
 drift report                                     ├─ Result Cards + badges
 (Hellinger fidelity + diff)                      ├─ Compliance + attestations
                                                  └─ Public corpus + leaderboard

You can use QuantumLedger entirely offline (capture, list, reproduce), or push your runs to a hosted or self-hosted server to publish cards, run compliance, and compare across the public corpus.

Open core

The client SDK, vendor connectors, provenance schema, and the public Result Cards / badges are Apache-2.0. The hosted server (reproduce engine, analytics, compliance rule engine, governance) is source-available under BUSL-1.1. See Libraries & downloads.

What QuantumLedger is not

It is not quantum hardware or control electronics, not a circuit IDE or scheduler, not an error-mitigation product, and not a general MLOps platform. It is not an accredited auditor — it produces the evidence and signed attestations; your compliance team (or an auditor) verifies them.

Next steps