61 lines
5.1 KiB
Plaintext
61 lines
5.1 KiB
Plaintext
---
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title: XXDecomposer
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description: API reference for qiskit.synthesis.XXDecomposer
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in_page_toc_min_heading_level: 1
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python_api_type: class
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python_api_name: qiskit.synthesis.XXDecomposer
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---
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# XXDecomposer
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<Class id="qiskit.synthesis.XXDecomposer" isDedicatedPage={true} github="https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/synthesis/two_qubit/xx_decompose/decomposer.py#L55-L324" signature="qiskit.synthesis.XXDecomposer(basis_fidelity=1.0, euler_basis='U', embodiments=None, backup_optimizer=None)" modifiers="class">
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Bases: [`object`](https://docs.python.org/3/library/functions.html#object "(in Python v3.12)")
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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 $alpha$).
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**Parameters**
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* **basis\_fidelity** ([*dict*](https://docs.python.org/3/library/stdtypes.html#dict "(in Python v3.12)") *|*[*float*](https://docs.python.org/3/library/functions.html#float "(in Python v3.12)")) – 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}`.
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* **euler\_basis** ([*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.12)")) – Basis string provided to [`OneQubitEulerDecomposer`](qiskit.synthesis.OneQubitEulerDecomposer "qiskit.synthesis.OneQubitEulerDecomposer") for 1Q synthesis. Defaults to `"U"`.
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* **embodiments** ([*dict*](https://docs.python.org/3/library/stdtypes.html#dict "(in Python v3.12)")*\[*[*float*](https://docs.python.org/3/library/functions.html#float "(in Python v3.12)")*,* [*QuantumCircuit*](qiskit.circuit.QuantumCircuit "qiskit.circuit.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`](qiskit.circuit.library.CXGate "qiskit.circuit.library.CXGate").
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* **backup\_optimizer** (*Callable\[...,* [*QuantumCircuit*](qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit")*] | None*) – If supplied, defers synthesis to this callable when [`XXDecomposer`](#qiskit.synthesis.XXDecomposer "qiskit.synthesis.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.
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<Admonition title="Note" type="note">
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If `embodiments` is not passed, or if an entry is missing, it will be populated as needed using the method `_default_embodiment`.
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</Admonition>
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### \_\_call\_\_
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<Function id="qiskit.synthesis.XXDecomposer.__call__" github="https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/synthesis/two_qubit/xx_decompose/decomposer.py#L228-L324" signature="__call__(unitary, basis_fidelity=None, approximate=True, use_dag=False)">
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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.
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**Parameters**
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* **unitary** ([*Operator*](qiskit.quantum_info.Operator "qiskit.quantum_info.Operator") *or ndarray*) – $4 \times 4$ unitary to synthesize.
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* **basis\_fidelity** ([*dict*](https://docs.python.org/3/library/stdtypes.html#dict "(in Python v3.12)") *or*[*float*](https://docs.python.org/3/library/functions.html#float "(in Python v3.12)")) – 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.
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* **approximate** ([*bool*](https://docs.python.org/3/library/functions.html#bool "(in Python v3.12)")) – Approximates if basis fidelities are less than 1.0 .
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* **use\_dag** ([*bool*](https://docs.python.org/3/library/functions.html#bool "(in Python v3.12)")) – If true a [`DAGCircuit`](qiskit.dagcircuit.DAGCircuit "qiskit.dagcircuit.DAGCircuit") is returned instead of a `QuantumCircuit` when this class is called.
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**Returns**
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Synthesized circuit.
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**Return type**
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[QuantumCircuit](qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit")
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</Function>
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## Methods
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### num\_basis\_gates
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<Function id="qiskit.synthesis.XXDecomposer.num_basis_gates" github="https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/synthesis/two_qubit/xx_decompose/decomposer.py#L185-L201" signature="num_basis_gates(unitary)">
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Counts the number of gates that would be emitted during re-synthesis.
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<Admonition title="Note" type="note">
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This method is used by [`ConsolidateBlocks`](qiskit.transpiler.passes.ConsolidateBlocks "qiskit.transpiler.passes.ConsolidateBlocks").
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</Admonition>
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</Function>
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</Class>
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