build_overlap_meta

build_overlap_meta(cost_circuit)

Build the compute-uncompute overlap circuit from a cost ansatz.

The forward block is the ansatz on its original parameters; the backward block is the ansatz inverted (QuantumCircuit.inverse() flips each rotation, e.g. RX(θ) → RX(-θ)) on a disjoint parameter namespace. The returned MetaCircuit measures all qubits as a probability distribution; its parameters are ordered (*θ_fwd, *θ_bwd) (each of length d), so binding a flat 2d vector [θ_fwd | θ_bwd] gives

\[P(0^n) = |\langle 0|U(\theta_\text{bwd})^\dagger U(\theta_\text{fwd})|0\rangle|^2 = F(\theta_\text{fwd}, \theta_\text{bwd}),\]

which is symmetric in its arguments. The result format is left unset — the probs MeasurementStage assigns it during expansion, as for the sample pipeline.

Return type:

MetaCircuit