iqm.benchmarks.entanglement.ghz_optimal.select_ghz_tree

iqm.benchmarks.entanglement.ghz_optimal.select_ghz_tree(qubit_layout: Sequence[int], backend: IQMBackendBase, metrics: Mapping[str, Mapping[int | tuple[int, int], float]], num_qubits: int | None = None, options: TreeSearchOptions | None = None, rank: int = 0) → TreeCandidate

Choose the qubits, the tree and the gate order of the GHZ state.

Parameters:

• qubit_layout (Sequence[int]) – The subset of system-qubits used in the protocol, indexed from 0.

• backend (IQMBackendBase) – The backend whose coupling map defines the connectivity.

• metrics (Mapping[str, Mapping[int | tuple[int, int], float]]) – The metrics dictionary from extract_fidelities_unified().

• num_qubits (int | None) – Size of the GHZ state; None uses every qubit of the layout.

• options (TreeSearchOptions | None) – What the search minimizes; defaults to TreeSearchOptions.

• rank (int) – Which candidate of rank_ghz_trees() to use, 0 being the best-scoring one. A rank beyond the last candidate falls back to the last one with a warning, rather than failing a run that has already built its circuits.

Returns:

The chosen candidate.

Raises:

ValueError – If options.objective is not one of TREE_OBJECTIVES.

Return type:

TreeCandidate