383 lines
14 KiB
Plaintext
383 lines
14 KiB
Plaintext
---
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title: SwapGate (v0.26)
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description: API reference for qiskit.circuit.library.SwapGate in qiskit v0.26
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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.SwapGate
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---
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<span id="qiskit-circuit-library-swapgate" />
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# qiskit.circuit.library.SwapGate
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<Class id="qiskit.circuit.library.SwapGate" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.17/qiskit/circuit/library/standard_gates/swap.py" signature="SwapGate(label=None)" modifiers="class">
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The SWAP gate.
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This is a symmetric and Clifford gate.
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**Circuit symbol:**
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```python
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q_0: ─X─
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│
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q_1: ─X─
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```
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**Matrix Representation:**
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$$
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\begin{split}SWAP =
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\begin{pmatrix}
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1 & 0 & 0 & 0 \\
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0 & 0 & 1 & 0 \\
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0 & 1 & 0 & 0 \\
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0 & 0 & 0 & 1
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\end{pmatrix}\end{split}
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$$
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The gate is equivalent to a state swap and is a classical logic gate.
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$$
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|a, b\rangle \rightarrow |b, a\rangle
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$$
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Create new SWAP gate.
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### \_\_init\_\_
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<Function id="qiskit.circuit.library.SwapGate.__init__" signature="__init__(label=None)">
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Create new SWAP gate.
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</Function>
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## Methods
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| ------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------ |
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| [`__init__`](#qiskit.circuit.library.SwapGate.__init__ "qiskit.circuit.library.SwapGate.__init__")(\[label]) | Create new SWAP gate. |
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| [`add_decomposition`](#qiskit.circuit.library.SwapGate.add_decomposition "qiskit.circuit.library.SwapGate.add_decomposition")(decomposition) | Add a decomposition of the instruction to the SessionEquivalenceLibrary. |
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| [`assemble`](#qiskit.circuit.library.SwapGate.assemble "qiskit.circuit.library.SwapGate.assemble")() | Assemble a QasmQobjInstruction |
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| [`broadcast_arguments`](#qiskit.circuit.library.SwapGate.broadcast_arguments "qiskit.circuit.library.SwapGate.broadcast_arguments")(qargs, cargs) | Validation and handling of the arguments and its relationship. |
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| [`c_if`](#qiskit.circuit.library.SwapGate.c_if "qiskit.circuit.library.SwapGate.c_if")(classical, val) | Add classical condition on register classical and value val. |
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| [`control`](#qiskit.circuit.library.SwapGate.control "qiskit.circuit.library.SwapGate.control")(\[num\_ctrl\_qubits, label, ctrl\_state]) | Return a (multi-)controlled-SWAP gate. |
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| [`copy`](#qiskit.circuit.library.SwapGate.copy "qiskit.circuit.library.SwapGate.copy")(\[name]) | Copy of the instruction. |
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| [`inverse`](#qiskit.circuit.library.SwapGate.inverse "qiskit.circuit.library.SwapGate.inverse")() | Return inverse Swap gate (itself). |
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| [`is_parameterized`](#qiskit.circuit.library.SwapGate.is_parameterized "qiskit.circuit.library.SwapGate.is_parameterized")() | Return True .IFF. |
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| [`mirror`](#qiskit.circuit.library.SwapGate.mirror "qiskit.circuit.library.SwapGate.mirror")() | DEPRECATED: use instruction.reverse\_ops(). |
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| [`power`](#qiskit.circuit.library.SwapGate.power "qiskit.circuit.library.SwapGate.power")(exponent) | Creates a unitary gate as gate^exponent. |
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| [`qasm`](#qiskit.circuit.library.SwapGate.qasm "qiskit.circuit.library.SwapGate.qasm")() | Return a default OpenQASM string for the instruction. |
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| [`repeat`](#qiskit.circuit.library.SwapGate.repeat "qiskit.circuit.library.SwapGate.repeat")(n) | Creates an instruction with gate repeated n amount of times. |
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| [`reverse_ops`](#qiskit.circuit.library.SwapGate.reverse_ops "qiskit.circuit.library.SwapGate.reverse_ops")() | For a composite instruction, reverse the order of sub-instructions. |
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| [`soft_compare`](#qiskit.circuit.library.SwapGate.soft_compare "qiskit.circuit.library.SwapGate.soft_compare")(other) | Soft comparison between gates. |
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| [`to_matrix`](#qiskit.circuit.library.SwapGate.to_matrix "qiskit.circuit.library.SwapGate.to_matrix")() | Return a Numpy.array for the gate unitary matrix. |
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| [`validate_parameter`](#qiskit.circuit.library.SwapGate.validate_parameter "qiskit.circuit.library.SwapGate.validate_parameter")(parameter) | Gate parameters should be int, float, or ParameterExpression |
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## Attributes
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| -------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------- |
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| [`decompositions`](#qiskit.circuit.library.SwapGate.decompositions "qiskit.circuit.library.SwapGate.decompositions") | Get the decompositions of the instruction from the SessionEquivalenceLibrary. |
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| [`definition`](#qiskit.circuit.library.SwapGate.definition "qiskit.circuit.library.SwapGate.definition") | Return definition in terms of other basic gates. |
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| [`duration`](#qiskit.circuit.library.SwapGate.duration "qiskit.circuit.library.SwapGate.duration") | Get the duration. |
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| [`label`](#qiskit.circuit.library.SwapGate.label "qiskit.circuit.library.SwapGate.label") | Return gate label |
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| [`params`](#qiskit.circuit.library.SwapGate.params "qiskit.circuit.library.SwapGate.params") | return instruction params. |
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| [`unit`](#qiskit.circuit.library.SwapGate.unit "qiskit.circuit.library.SwapGate.unit") | Get the time unit of duration. |
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### add\_decomposition
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<Function id="qiskit.circuit.library.SwapGate.add_decomposition" signature="add_decomposition(decomposition)">
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Add a decomposition of the instruction to the SessionEquivalenceLibrary.
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</Function>
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### assemble
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<Function id="qiskit.circuit.library.SwapGate.assemble" signature="assemble()">
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Assemble a QasmQobjInstruction
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**Return type**
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`Instruction`
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</Function>
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### broadcast\_arguments
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<Function id="qiskit.circuit.library.SwapGate.broadcast_arguments" signature="broadcast_arguments(qargs, cargs)">
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Validation and handling of the arguments and its relationship.
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For example, `cx([q[0],q[1]], q[2])` means `cx(q[0], q[2]); cx(q[1], q[2])`. This method yields the arguments in the right grouping. In the given example:
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```python
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in: [[q[0],q[1]], q[2]],[]
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outs: [q[0], q[2]], []
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[q[1], q[2]], []
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```
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The general broadcasting rules are:
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> * If len(qargs) == 1:
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>
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> ```python
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> [q[0], q[1]] -> [q[0]],[q[1]]
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> ```
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>
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> * If len(qargs) == 2:
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>
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> ```python
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> [[q[0], q[1]], [r[0], r[1]]] -> [q[0], r[0]], [q[1], r[1]]
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> [[q[0]], [r[0], r[1]]] -> [q[0], r[0]], [q[0], r[1]]
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> [[q[0], q[1]], [r[0]]] -> [q[0], r[0]], [q[1], r[0]]
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> ```
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>
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> * If len(qargs) >= 3:
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>
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> ```python
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> [q[0], q[1]], [r[0], r[1]], ...] -> [q[0], r[0], ...], [q[1], r[1], ...]
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> ```
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**Parameters**
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* **qargs** (`List`) – List of quantum bit arguments.
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* **cargs** (`List`) – List of classical bit arguments.
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**Return type**
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`Tuple`\[`List`, `List`]
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**Returns**
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A tuple with single arguments.
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**Raises**
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**CircuitError** – If the input is not valid. For example, the number of arguments does not match the gate expectation.
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</Function>
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### c\_if
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<Function id="qiskit.circuit.library.SwapGate.c_if" signature="c_if(classical, val)">
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Add classical condition on register classical and value val.
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</Function>
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### control
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<Function id="qiskit.circuit.library.SwapGate.control" signature="control(num_ctrl_qubits=1, label=None, ctrl_state=None)">
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Return a (multi-)controlled-SWAP gate.
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One control returns a CSWAP (Fredkin) 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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### copy
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<Function id="qiskit.circuit.library.SwapGate.copy" signature="copy(name=None)">
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Copy of the instruction.
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**Parameters**
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**name** (*str*) – name to be given to the copied circuit, if None then the name stays the same.
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**Returns**
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**a copy of the current instruction, with the name**
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updated if it was provided
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**Return type**
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[qiskit.circuit.Instruction](qiskit.circuit.Instruction "qiskit.circuit.Instruction")
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</Function>
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### decompositions
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<Attribute id="qiskit.circuit.library.SwapGate.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.SwapGate.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.SwapGate.duration">
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Get the duration.
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</Attribute>
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### inverse
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<Function id="qiskit.circuit.library.SwapGate.inverse" signature="inverse()">
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Return inverse Swap gate (itself).
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</Function>
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### is\_parameterized
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<Function id="qiskit.circuit.library.SwapGate.is_parameterized" signature="is_parameterized()">
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Return True .IFF. instruction is parameterized else False
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</Function>
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### label
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<Attribute id="qiskit.circuit.library.SwapGate.label">
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Return gate label
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**Return type**
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`str`
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</Attribute>
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### mirror
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<Function id="qiskit.circuit.library.SwapGate.mirror" signature="mirror()">
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DEPRECATED: use instruction.reverse\_ops().
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**Returns**
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**a new instruction with sub-instructions**
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reversed.
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**Return type**
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[qiskit.circuit.Instruction](qiskit.circuit.Instruction "qiskit.circuit.Instruction")
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</Function>
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### params
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<Attribute id="qiskit.circuit.library.SwapGate.params">
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return instruction params.
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</Attribute>
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### power
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<Function id="qiskit.circuit.library.SwapGate.power" signature="power(exponent)">
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Creates a unitary gate as gate^exponent.
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**Parameters**
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**exponent** (*float*) – Gate^exponent
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**Returns**
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To which to\_matrix is self.to\_matrix^exponent.
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**Return type**
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[qiskit.extensions.UnitaryGate](qiskit.extensions.UnitaryGate "qiskit.extensions.UnitaryGate")
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**Raises**
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**CircuitError** – If Gate is not unitary
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</Function>
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### qasm
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<Function id="qiskit.circuit.library.SwapGate.qasm" signature="qasm()">
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Return a default OpenQASM string for the instruction.
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Derived instructions may override this to print in a different format (e.g. measure q\[0] -> c\[0];).
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</Function>
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### repeat
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<Function id="qiskit.circuit.library.SwapGate.repeat" signature="repeat(n)">
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Creates an instruction with gate repeated n amount of times.
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**Parameters**
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**n** (*int*) – Number of times to repeat the instruction
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**Returns**
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Containing the definition.
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**Return type**
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[qiskit.circuit.Instruction](qiskit.circuit.Instruction "qiskit.circuit.Instruction")
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**Raises**
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**CircuitError** – If n \< 1.
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</Function>
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### reverse\_ops
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<Function id="qiskit.circuit.library.SwapGate.reverse_ops" signature="reverse_ops()">
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For a composite instruction, reverse the order of sub-instructions.
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This is done by recursively reversing all sub-instructions. It does not invert any gate.
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**Returns**
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**a new instruction with**
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sub-instructions reversed.
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**Return type**
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[qiskit.circuit.Instruction](qiskit.circuit.Instruction "qiskit.circuit.Instruction")
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</Function>
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### soft\_compare
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<Function id="qiskit.circuit.library.SwapGate.soft_compare" signature="soft_compare(other)">
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Soft comparison between gates. Their names, number of qubits, and classical bit numbers must match. The number of parameters must match. Each parameter is compared. If one is a ParameterExpression then it is not taken into account.
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**Parameters**
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**other** (*instruction*) – other instruction.
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**Returns**
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are self and other equal up to parameter expressions.
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**Return type**
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bool
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</Function>
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### to\_matrix
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<Function id="qiskit.circuit.library.SwapGate.to_matrix" signature="to_matrix()">
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Return a Numpy.array for the gate unitary matrix.
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**Returns**
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if the Gate subclass has a matrix definition.
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**Return type**
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np.ndarray
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**Raises**
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**CircuitError** – If a Gate subclass does not implement this method an exception will be raised when this base class method is called.
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</Function>
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### unit
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<Attribute id="qiskit.circuit.library.SwapGate.unit">
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Get the time unit of duration.
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</Attribute>
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### validate\_parameter
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<Function id="qiskit.circuit.library.SwapGate.validate_parameter" signature="validate_parameter(parameter)">
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Gate parameters should be int, float, or ParameterExpression
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</Function>
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</Class>
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