XXDecomposer
class qiskit.synthesis.XXDecomposer(basis_fidelity=1.0, euler_basis='U', embodiments=None, backup_optimizer=None)
Bases: object
A class for optimal decomposition of 2-qubit unitaries into 2-qubit basis gates of XX type (i.e., each locally equivalent to for a possibly varying ).
Parameters
- basis_fidelity (dict |float) – available strengths and fidelity of each. Can be either (1) a dictionary mapping
XXangle values to fidelity at that angle; or (2) a single floatf, interpreted as{pi: f, pi/2: f/2, pi/3: f/3}. - euler_basis (str) – Basis string provided to
OneQubitEulerDecomposerfor 1Q synthesis. Defaults to"U". - embodiments (dict[float, QuantumCircuit] | None) – A dictionary mapping interaction strengths alpha to native circuits which embody the gate . Strengths are taken so that represents the class of a full
CXGate. - backup_optimizer (Callable[..., QuantumCircuit] | None) – If supplied, defers synthesis to this callable when
XXDecomposerhas no efficient decomposition of its own. Useful for special cases involving 2 or 3 applications of , in which case standard synthesis methods provide lower 1Q gate count.
If embodiments is not passed, or if an entry is missing, it will be populated as needed using the method _default_embodiment.
__call__
__call__(unitary, basis_fidelity=None, approximate=True, use_dag=False)
Fashions a circuit which (perhaps approximately) models the special unitary operation unitary, using the circuit templates supplied at initialization as embodiments. The routine uses basis_fidelity to select the optimal circuit template, including when performing exact synthesis; the contents of basis_fidelity is a dictionary mapping interaction strengths (scaled so that corresponds to ) to circuit fidelities.
Parameters
- unitary (Operator or ndarray) – unitary to synthesize.
- basis_fidelity (dict orfloat) – Fidelity of basis gates. Can be either (1) a dictionary mapping
XXangle values to fidelity at that angle; or (2) a single floatf, interpreted as{pi: f, pi/2: f/2, pi/3: f/3}. If given, overrides the basis_fidelity given at init. - approximate (bool) – Approximates if basis fidelities are less than 1.0 .
- use_dag (bool) – If true a
DAGCircuitis returned instead of aQuantumCircuitwhen this class is called.
Returns
Synthesized circuit.
Return type
Methods
num_basis_gates
num_basis_gates(unitary)
Counts the number of gates that would be emitted during re-synthesis.
This method is used by ConsolidateBlocks.