XXDecomposer

qiskit.synthesis.XXDecomposer(basis_fidelity=1.0, euler_basis='U', embodiments=None, backup_optimizer=None)

Bases: object(opens in a new tab)

A class for optimal decomposition of 2-qubit unitaries into 2-qubit basis gates of XX type (i.e., each locally equivalent to $CAN(\alpha, 0, 0)$ for a possibly varying $alpha$ ).

Parameters

basis_fidelity (dict(opens in a new tab) |float(opens in a new tab)) – available strengths and fidelity of each. Can be either (1) a dictionary mapping XX angle values to fidelity at that angle; or (2) a single float f, interpreted as {pi: f, pi/2: f/2, pi/3: f/3}.
euler_basis (str(opens in a new tab)) – Basis string provided to OneQubitEulerDecomposer for 1Q synthesis. Defaults to "U".
embodiments (dict(opens in a new tab)[float(opens in a new tab), QuantumCircuit] | None) – A dictionary mapping interaction strengths alpha to native circuits which embody the gate $CAN(\alpha, 0, 0)$ . Strengths are taken so that $\pi/2$ represents the class of a full CXGate.
backup_optimizer (Callable[..., QuantumCircuit] | None) – If supplied, defers synthesis to this callable when XXDecomposer has no efficient decomposition of its own. Useful for special cases involving 2 or 3 applications of $XX(\pi/2)$ , in which case standard synthesis methods provide lower 1Q gate count.

Note

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)

GitHub

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 $CX = RZX(\pi/2)$ corresponds to $\pi/2$ ) to circuit fidelities.

Parameters

unitary (Operator or ndarray) – $4 \times 4$ unitary to synthesize.
basis_fidelity (dict(opens in a new tab) orfloat(opens in a new tab)) – Fidelity of basis gates. Can be either (1) a dictionary mapping XX angle values to fidelity at that angle; or (2) a single float f, interpreted as {pi: f, pi/2: f/2, pi/3: f/3}. If given, overrides the basis_fidelity given at init.
approximate (bool(opens in a new tab)) – Approximates if basis fidelities are less than 1.0 .

Returns

Synthesized circuit.

Return type

QuantumCircuit

Methods

num_basis_gates

num_basis_gates(unitary)

GitHub

Counts the number of gates that would be emitted during re-synthesis.

Note

This method is used by ConsolidateBlocks.

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