data(calibration): add IQM Emerald calibration snapshot (2026-06-06)

[PlayerPlanet]

Live calibration snapshot pulled from IQM Resonance via iqm_client (iqm.qiskit_iqm.IQMProvider + backend.metrics.get_gate_fidelity).

What this adds

• iqm_utils/calibration_data/emerald_calibration_2026-06-06T09-24-08Z.json (23 KB, schema v1.0)
• 54 qubits (PRX fidelity, all calibrated)
• 86 couplers (CZ fidelity, 1 missing: QB50-QB51)
• Mean PRX fidelity: 0.9992 (min 0.9937)
• Mean CZ fidelity: 0.9875 (min 0.7990)

Notable for surface-code layout

The worst coupler by a wide margin is QB38-QB46 with CZ fidelity 0.7990 — the next-worst is QB20-QB12 at 0.9215. When build_emerald_qubit_map_optimizing chooses a 5x5 patch for the distance-3 rotated code, it should explicitly avoid this edge; the snapshot here is the data source for that decision.

Reproducibility

Re-fetch with the standard IQMProvider call:

from iqm.qiskit_iqm import IQMProvider
import os

provider = IQMProvider(
    "https://resonance.meetiqm.com",
    quantum_computer="emerald",
    token=os.environ["IQM_API_KEY"],
)
backend = provider.get_backend(use_metrics=True)
# Then iterate backend.architecture.qubits / gates["cz"].loci and call
# backend.metrics.get_gate_fidelity(...)

Tokens are not embedded in the JSON (the source block only records URL and method). Server-side warnings about Missing fidelity for cz.crf_crf.QB50__QB51 are expected and reflected in the missing and warnings blocks of the snapshot.