BasisTranslator¶

class
BasisTranslator
(*args, **kwargs)[source]¶ Bases:
qiskit.transpiler.basepasses.TransformationPass
Translates gates to a target basis by searching for a set of translations from a given EquivalenceLibrary.
This pass operates in several steps:
Determine the source basis from the input circuit.
Perform an A* search over basis sets, starting from the source basis and targeting the device’s target_basis, with edges discovered from the provided EquivalenceLibrary. The heuristic used by the A* search is the number of distinct circuit basis gates not in the target_basis, plus the number of distinct device basis gates not used in the current basis.
The found path, as a set of rules from the EquivalenceLibrary, is composed into a set of gate replacement rules.
The composed replacement rules are applied inplace to each op node which is not already in the target_basis.
If the target keyword argument is specified and that
Target
objects contains operations which are nonglobal (i.e. they are defined only for a subset of qubits), as calculated byget_non_global_operation_names()
, this pass will attempt to match the output translation to those constraints. For 1 qubit operations this is straightforward, the pass will perform a search using the union of the set of global operations with the set of operations defined solely on that qubit. For multiqubit gates this is a bit more involved, while the behavior is initially similar to the single qubit case, just using all the qubits the operation is run on (where order is not significant) isn’t sufficient. We also need to consider any potential local qubits defined on subsets of the quantum arguments for the multiqubit operation. This means the target used for the search of a nonglobal multiqubit gate is the union of global operations, nonglobal multiqubit gates sharing the same qubits, and any nonglobal gates defined on any subset of the qubits used.Note
In the case of nonglobal operations it is possible for a single execution of this pass to output an incomplete translation if any nonglobal gates are defined on qubits that are a subset of a larger multiqubit gate. For example, if you have a
u
gate only defined on qubit 0 and anx
gate only on qubit 1 it is possible when translating a 2 qubit operation on qubit 0 and 1 that the output might haveu
on qubit 1 andx
on qubit 0. Typically running this pass a second time will correct these issues.Initialize a BasisTranslator instance.
 Parameters
equivalence_library (EquivalenceLibrary) – The equivalence library which will be used by the BasisTranslator pass. (Instructions in this library will not be unrolled by this pass.)
target_basis (list[str]) – Target basis names to unroll to, e.g. [‘u3’, ‘cx’].
target (Target) – The backend compilation target
Methods
Return the name of the pass.
Translate an input DAGCircuit to the target basis.
Attributes

is_analysis_pass
¶ Check if the pass is an analysis pass.
If the pass is an AnalysisPass, that means that the pass can analyze the DAG and write the results of that analysis in the property set. Modifications on the DAG are not allowed by this kind of pass.

is_transformation_pass
¶ Check if the pass is a transformation pass.
If the pass is a TransformationPass, that means that the pass can manipulate the DAG, but cannot modify the property set (but it can be read).