133 lines
3.0 KiB
Plaintext
133 lines
3.0 KiB
Plaintext
---
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title: XGate (v0.29)
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description: API reference for qiskit.circuit.library.XGate in qiskit v0.29
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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.circuit.library.XGate
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---
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# XGate
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<Class id="qiskit.circuit.library.XGate" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.18/qiskit/circuit/library/standard_gates/x.py" signature="XGate(label=None)" modifiers="class">
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Bases: `qiskit.circuit.gate.Gate`
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The single-qubit Pauli-X gate ($\sigma_x$).
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**Matrix Representation:**
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$$
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\begin{split}X = \begin{pmatrix}
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0 & 1 \\
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1 & 0
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\end{pmatrix}\end{split}
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$$
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**Circuit symbol:**
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```python
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┌───┐
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q_0: ┤ X ├
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└───┘
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```
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Equivalent to a $\pi$ radian rotation about the X axis.
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<Admonition title="Note" type="note">
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A global phase difference exists between the definitions of $RX(\pi)$ and $X$.
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$$
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\begin{split}RX(\pi) = \begin{pmatrix}
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0 & -i \\
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-i & 0
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\end{pmatrix}
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= -i X\end{split}
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$$
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</Admonition>
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The gate is equivalent to a classical bit flip.
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$$
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\begin{split}|0\rangle \rightarrow |1\rangle \\
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|1\rangle \rightarrow |0\rangle\end{split}
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$$
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Create new X gate.
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## Methods Defined Here
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<span id="qiskit-circuit-library-xgate-control" />
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### control
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<Function id="qiskit.circuit.library.XGate.control" signature="XGate.control(num_ctrl_qubits=1, label=None, ctrl_state=None)">
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Return a (multi-)controlled-X gate.
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One control returns a CX gate. Two controls returns a CCX gate.
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**Parameters**
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* **num\_ctrl\_qubits** (*int*) – number of control qubits.
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* **label** (*str or None*) – An optional label for the gate \[Default: None]
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* **ctrl\_state** (*int or str or None*) – control state expressed as integer, string (e.g. ‘110’), or None. If None, use all 1s.
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**Returns**
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controlled version of this gate.
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**Return type**
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[ControlledGate](qiskit.circuit.ControlledGate "qiskit.circuit.ControlledGate")
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</Function>
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<span id="qiskit-circuit-library-xgate-inverse" />
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### inverse
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<Function id="qiskit.circuit.library.XGate.inverse" signature="XGate.inverse()">
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Return inverted X gate (itself).
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</Function>
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## Attributes
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### decompositions
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<Attribute id="qiskit.circuit.library.XGate.decompositions">
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Get the decompositions of the instruction from the SessionEquivalenceLibrary.
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</Attribute>
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### definition
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<Attribute id="qiskit.circuit.library.XGate.definition">
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Return definition in terms of other basic gates.
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</Attribute>
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### duration
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<Attribute id="qiskit.circuit.library.XGate.duration">
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Get the duration.
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</Attribute>
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### label
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<Attribute id="qiskit.circuit.library.XGate.label">
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Return instruction label
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**Return type**
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`str`
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</Attribute>
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### params
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<Attribute id="qiskit.circuit.library.XGate.params">
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return instruction params.
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</Attribute>
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### unit
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<Attribute id="qiskit.circuit.library.XGate.unit">
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Get the time unit of duration.
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</Attribute>
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</Class>
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