Correctness scope

Single-device circuits

Limbo is a faithful transport for circuits that fit on your chosen device. If circuit_qubits ≤ device_qubits, the SDK ingests, optionally pre-optimizes (Qiskit passes only), transpiles against the device's coupling map, and submits through the vendor's official SDK. The result is semantically identical to what Qiskit plus the vendor SDK would produce directly.

Multi-chip routing

Research-grade

When a circuit doesn't fit on one device and the SDK partitions it across several QPUs, the result is research-grade. No commercial cloud QPU exposes a multi-chip interconnect today, so the cross-chip operations the SDK emits can only be validated in simulation.

Don't send a num_qpus > 1 configuration to a single-chip cloud backend and expect correct results. The cross-chip entanglement won't be implemented by that hardware.

The multi-chip benchmark results are measured against TKET under a calibrated noise model. The method and its limits are in the preprint.