Optimizations

class Configuration.Optimizations

Options that influence which circuit optimizations are applied during pre-processing.

property backpropagate_output_permutation

Backpropagate the output permutation to the input permutation. Defaults to False since this might mess up the initially given input permutation. Can be helpful for dynamic quantum circuits that have been transformed to a static circuit by enabling the transform_dynamic_circuit optimization.

property elide_permutations

Elide permutations from the circuit by permuting the qubits in the circuit and eliminating SWAP gates from the circuits. Defaults to True as this typically boosts performance.

property fix_output_permutation_mismatch

Try to fix potential mismatches in output permutations. This is experimental and, hence, defaults to False.

property fuse_single_qubit_gates

Fuse consecutive single-qubit gates by grouping them together. Defaults to True as this typically increases the performance of the subsequent equivalence check.

property reconstruct_swaps

Try to reconstruct SWAP gates that have been decomposed (into a sequence of 3 CNOT gates) or optimized away (as a consequence of a SWAP preceded or followed by a CNOT on the same qubits). Defaults to True since this reconstruction enables the efficient tracking of logical to physical qubit permutations throughout circuits that have been mapped to a target architecture.

property remove_diagonal_gates_before_measure

Remove any diagonal gates at the end of the circuit. This might be desirable since any diagonal gate in front of a measurement does not influence the probabilities of the respective states. Defaults to False since, in general, circuits differing by diagonal gates at the end should still be considered non-equivalent.

property reorder_operations

The operations of a circuit are stored in a sequential container. This introduces some dependencies in the order of operations that are not naturally present in the quantum circuit. As a consequence, two quantum circuits that contain exactly the same operations, list their operations in different ways, also apply there operations in a different order. This optimization pass established a canonical ordering of operations by, first, constructing a directed, acyclic graph for the operations and, then, traversing it in a breadth-first fashion. Defaults to True.

property transform_dynamic_circuit

Circuits containing dynamic circuit primitives such as mid-circuit measurements, resets, or classically-controlled operations cannot be verified in a straight-forward fashion due to the non-unitary nature of these primitives, which is why this setting defaults to False. By enabling this optimization, any dynamic circuit is first transformed to a circuit without non-unitary primitives by, first, substituting qubit resets with new qubits and, then, applying the deferred measurement principle to defer measurements to the end.