155 lines
3.6 KiB
Plaintext
155 lines
3.6 KiB
Plaintext
---
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title: YGate
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description: API reference for qiskit.circuit.library.YGate
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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.YGate
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---
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# YGate
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<Class id="qiskit.circuit.library.YGate" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.24/qiskit/circuit/library/standard_gates/y.py" signature="YGate(label=None)" modifiers="class">
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Bases: [`Gate`](qiskit.circuit.Gate "qiskit.circuit.gate.Gate")
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The single-qubit Pauli-Y gate ($\sigma_y$).
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Can be applied to a [`QuantumCircuit`](qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit") with the [`y()`](qiskit.circuit.QuantumCircuit#y "qiskit.circuit.QuantumCircuit.y") method.
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**Matrix Representation:**
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$$
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\begin{split}Y = \begin{pmatrix}
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0 & -i \\
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i & 0
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\end{pmatrix}\end{split}
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$$
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**Circuit symbol:**
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```python
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┌───┐
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q_0: ┤ Y ├
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└───┘
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```
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Equivalent to a $\pi$ radian rotation about the Y axis.
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<Admonition title="Note" type="note">
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A global phase difference exists between the definitions of $RY(\pi)$ and $Y$.
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$$
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\begin{split}RY(\pi) = \begin{pmatrix}
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0 & -1 \\
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1 & 0
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\end{pmatrix}
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= -i Y\end{split}
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$$
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</Admonition>
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The gate is equivalent to a bit and phase flip.
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$$
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\begin{split}|0\rangle \rightarrow i|1\rangle \\
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|1\rangle \rightarrow -i|0\rangle\end{split}
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$$
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Create new Y gate.
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## Methods Defined Here
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<span id="qiskit-circuit-library-ygate-control" />
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### control
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<Function id="qiskit.circuit.library.YGate.control" signature="YGate.control(num_ctrl_qubits=1, label=None, ctrl_state=None)">
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Return a (multi-)controlled-Y gate.
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One control returns a CY 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-ygate-inverse" />
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### inverse
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<Function id="qiskit.circuit.library.YGate.inverse" signature="YGate.inverse()">
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Return inverted Y gate ($Y^{\dagger} = Y$)
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</Function>
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## Attributes
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### condition\_bits
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<Attribute id="qiskit.circuit.library.YGate.condition_bits">
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Get Clbits in condition.
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</Attribute>
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### decompositions
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<Attribute id="qiskit.circuit.library.YGate.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.YGate.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.YGate.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.YGate.label">
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Return instruction label
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</Attribute>
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### name
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<Attribute id="qiskit.circuit.library.YGate.name">
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Return the name.
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</Attribute>
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### num\_clbits
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<Attribute id="qiskit.circuit.library.YGate.num_clbits">
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Return the number of clbits.
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</Attribute>
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### num\_qubits
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<Attribute id="qiskit.circuit.library.YGate.num_qubits">
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Return the number of qubits.
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</Attribute>
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### params
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<Attribute id="qiskit.circuit.library.YGate.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.YGate.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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