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---
title: iSwapGate (v0.26)
description: API reference for qiskit.circuit.library.iSwapGate in qiskit v0.26
in_page_toc_min_heading_level: 1
python_api_type: class
python_api_name: qiskit.circuit.library.iSwapGate
---
<span id="qiskit-circuit-library-iswapgate" />
# qiskit.circuit.library.iSwapGate
<Class id="qiskit.circuit.library.iSwapGate" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.17/qiskit/circuit/library/standard_gates/iswap.py" signature="iSwapGate" modifiers="class">
iSWAP gate.
A 2-qubit XX+YY interaction. This is a Clifford and symmetric gate. Its action is to swap two qubit states and phase the $|01\rangle$ and $|10\rangle$ amplitudes by i.
**Circuit Symbol:**
```python
q_0: ─⨂─
q_1: ─⨂─
```
**Reference Implementation:**
```python
┌───┐┌───┐ ┌───┐
q_0: ┤ S ├┤ H ├──■──┤ X ├─────
├───┤└───┘┌─┴─┐└─┬─┘┌───┐
q_1: ┤ S ├─────┤ X ├──■──┤ H ├
└───┘ └───┘ └───┘
```
**Matrix Representation:**
$$
\begin{split}iSWAP = R_{XX+YY}(-\frac{\pi}{2})
= exp(i \frac{\pi}{4} (X{\otimes}X+Y{\otimes}Y)) =
\begin{pmatrix}
1 & 0 & 0 & 0 \\
0 & 0 & i & 0 \\
0 & i & 0 & 0 \\
0 & 0 & 0 & 1
\end{pmatrix}\end{split}
$$
This gate is equivalent to a SWAP up to a diagonal.
$$
\begin{split}iSWAP =
\begin{pmatrix}
1 & 0 & 0 & 0 \\
0 & 0 & 1 & 0 \\
0 & 1 & 0 & 0 \\
0 & 0 & 0 & 1
\end{pmatrix}
. \begin{pmatrix}
1 & 0 & 0 & 0 \\
0 & i & 0 & 0 \\
0 & 0 & i & 0 \\
0 & 0 & 0 & 1
\end{pmatrix}\end{split}
$$
Create new iSwap gate.
### \_\_init\_\_
<Function id="qiskit.circuit.library.iSwapGate.__init__" signature="__init__()">
Create new iSwap gate.
</Function>
## Methods
| | |
| --------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------ |
| [`__init__`](#qiskit.circuit.library.iSwapGate.__init__ "qiskit.circuit.library.iSwapGate.__init__")() | Create new iSwap gate. |
| [`add_decomposition`](#qiskit.circuit.library.iSwapGate.add_decomposition "qiskit.circuit.library.iSwapGate.add_decomposition")(decomposition) | Add a decomposition of the instruction to the SessionEquivalenceLibrary. |
| [`assemble`](#qiskit.circuit.library.iSwapGate.assemble "qiskit.circuit.library.iSwapGate.assemble")() | Assemble a QasmQobjInstruction |
| [`broadcast_arguments`](#qiskit.circuit.library.iSwapGate.broadcast_arguments "qiskit.circuit.library.iSwapGate.broadcast_arguments")(qargs, cargs) | Validation and handling of the arguments and its relationship. |
| [`c_if`](#qiskit.circuit.library.iSwapGate.c_if "qiskit.circuit.library.iSwapGate.c_if")(classical, val) | Add classical condition on register classical and value val. |
| [`control`](#qiskit.circuit.library.iSwapGate.control "qiskit.circuit.library.iSwapGate.control")(\[num\_ctrl\_qubits, label, ctrl\_state]) | Return controlled version of gate. |
| [`copy`](#qiskit.circuit.library.iSwapGate.copy "qiskit.circuit.library.iSwapGate.copy")(\[name]) | Copy of the instruction. |
| [`inverse`](#qiskit.circuit.library.iSwapGate.inverse "qiskit.circuit.library.iSwapGate.inverse")() | Invert this instruction. |
| [`is_parameterized`](#qiskit.circuit.library.iSwapGate.is_parameterized "qiskit.circuit.library.iSwapGate.is_parameterized")() | Return True .IFF. |
| [`mirror`](#qiskit.circuit.library.iSwapGate.mirror "qiskit.circuit.library.iSwapGate.mirror")() | DEPRECATED: use instruction.reverse\_ops(). |
| [`power`](#qiskit.circuit.library.iSwapGate.power "qiskit.circuit.library.iSwapGate.power")(exponent) | Creates a unitary gate as gate^exponent. |
| [`qasm`](#qiskit.circuit.library.iSwapGate.qasm "qiskit.circuit.library.iSwapGate.qasm")() | Return a default OpenQASM string for the instruction. |
| [`repeat`](#qiskit.circuit.library.iSwapGate.repeat "qiskit.circuit.library.iSwapGate.repeat")(n) | Creates an instruction with gate repeated n amount of times. |
| [`reverse_ops`](#qiskit.circuit.library.iSwapGate.reverse_ops "qiskit.circuit.library.iSwapGate.reverse_ops")() | For a composite instruction, reverse the order of sub-instructions. |
| [`soft_compare`](#qiskit.circuit.library.iSwapGate.soft_compare "qiskit.circuit.library.iSwapGate.soft_compare")(other) | Soft comparison between gates. |
| [`to_matrix`](#qiskit.circuit.library.iSwapGate.to_matrix "qiskit.circuit.library.iSwapGate.to_matrix")() | Return a Numpy.array for the gate unitary matrix. |
| [`validate_parameter`](#qiskit.circuit.library.iSwapGate.validate_parameter "qiskit.circuit.library.iSwapGate.validate_parameter")(parameter) | Gate parameters should be int, float, or ParameterExpression |
## Attributes
| | |
| ---------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------- |
| [`decompositions`](#qiskit.circuit.library.iSwapGate.decompositions "qiskit.circuit.library.iSwapGate.decompositions") | Get the decompositions of the instruction from the SessionEquivalenceLibrary. |
| [`definition`](#qiskit.circuit.library.iSwapGate.definition "qiskit.circuit.library.iSwapGate.definition") | Return definition in terms of other basic gates. |
| [`duration`](#qiskit.circuit.library.iSwapGate.duration "qiskit.circuit.library.iSwapGate.duration") | Get the duration. |
| [`label`](#qiskit.circuit.library.iSwapGate.label "qiskit.circuit.library.iSwapGate.label") | Return gate label |
| [`params`](#qiskit.circuit.library.iSwapGate.params "qiskit.circuit.library.iSwapGate.params") | return instruction params. |
| [`unit`](#qiskit.circuit.library.iSwapGate.unit "qiskit.circuit.library.iSwapGate.unit") | Get the time unit of duration. |
### add\_decomposition
<Function id="qiskit.circuit.library.iSwapGate.add_decomposition" signature="add_decomposition(decomposition)">
Add a decomposition of the instruction to the SessionEquivalenceLibrary.
</Function>
### assemble
<Function id="qiskit.circuit.library.iSwapGate.assemble" signature="assemble()">
Assemble a QasmQobjInstruction
**Return type**
`Instruction`
</Function>
### broadcast\_arguments
<Function id="qiskit.circuit.library.iSwapGate.broadcast_arguments" signature="broadcast_arguments(qargs, cargs)">
Validation and handling of the arguments and its relationship.
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:
```python
in: [[q[0],q[1]], q[2]],[]
outs: [q[0], q[2]], []
[q[1], q[2]], []
```
The general broadcasting rules are:
> * If len(qargs) == 1:
>
> ```python
> [q[0], q[1]] -> [q[0]],[q[1]]
> ```
>
> * If len(qargs) == 2:
>
> ```python
> [[q[0], q[1]], [r[0], r[1]]] -> [q[0], r[0]], [q[1], r[1]]
> [[q[0]], [r[0], r[1]]] -> [q[0], r[0]], [q[0], r[1]]
> [[q[0], q[1]], [r[0]]] -> [q[0], r[0]], [q[1], r[0]]
> ```
>
> * If len(qargs) >= 3:
>
> ```python
> [q[0], q[1]], [r[0], r[1]], ...] -> [q[0], r[0], ...], [q[1], r[1], ...]
> ```
**Parameters**
* **qargs** (`List`) List of quantum bit arguments.
* **cargs** (`List`) List of classical bit arguments.
**Return type**
`Tuple`\[`List`, `List`]
**Returns**
A tuple with single arguments.
**Raises**
**CircuitError** If the input is not valid. For example, the number of arguments does not match the gate expectation.
</Function>
### c\_if
<Function id="qiskit.circuit.library.iSwapGate.c_if" signature="c_if(classical, val)">
Add classical condition on register classical and value val.
</Function>
### control
<Function id="qiskit.circuit.library.iSwapGate.control" signature="control(num_ctrl_qubits=1, label=None, ctrl_state=None)">
Return controlled version of gate. See [`ControlledGate`](qiskit.circuit.ControlledGate "qiskit.circuit.ControlledGate") for usage.
**Parameters**
* **num\_ctrl\_qubits** (`Optional`\[`int`]) number of controls to add to gate (default=1)
* **label** (`Optional`\[`str`]) optional gate label
* **ctrl\_state** (`Union`\[`int`, `str`, `None`]) The control state in decimal or as a bitstring (e.g. 111). If None, use 2\*\*num\_ctrl\_qubits-1.
**Returns**
Controlled version of gate. This default algorithm uses num\_ctrl\_qubits-1 ancillae qubits so returns a gate of size num\_qubits + 2\*num\_ctrl\_qubits - 1.
**Return type**
[qiskit.circuit.ControlledGate](qiskit.circuit.ControlledGate "qiskit.circuit.ControlledGate")
**Raises**
**QiskitError** unrecognized mode or invalid ctrl\_state
</Function>
### copy
<Function id="qiskit.circuit.library.iSwapGate.copy" signature="copy(name=None)">
Copy of the instruction.
**Parameters**
**name** (*str*) name to be given to the copied circuit, if None then the name stays the same.
**Returns**
**a copy of the current instruction, with the name**
updated if it was provided
**Return type**
[qiskit.circuit.Instruction](qiskit.circuit.Instruction "qiskit.circuit.Instruction")
</Function>
### decompositions
<Attribute id="qiskit.circuit.library.iSwapGate.decompositions">
Get the decompositions of the instruction from the SessionEquivalenceLibrary.
</Attribute>
### definition
<Attribute id="qiskit.circuit.library.iSwapGate.definition">
Return definition in terms of other basic gates.
</Attribute>
### duration
<Attribute id="qiskit.circuit.library.iSwapGate.duration">
Get the duration.
</Attribute>
### inverse
<Function id="qiskit.circuit.library.iSwapGate.inverse" signature="inverse()">
Invert this instruction.
If the instruction is composite (i.e. has a definition), then its definition will be recursively inverted.
Special instructions inheriting from Instruction can implement their own inverse (e.g. T and Tdg, Barrier, etc.)
**Returns**
a fresh instruction for the inverse
**Return type**
[qiskit.circuit.Instruction](qiskit.circuit.Instruction "qiskit.circuit.Instruction")
**Raises**
**CircuitError** if the instruction is not composite and an inverse has not been implemented for it.
</Function>
### is\_parameterized
<Function id="qiskit.circuit.library.iSwapGate.is_parameterized" signature="is_parameterized()">
Return True .IFF. instruction is parameterized else False
</Function>
### label
<Attribute id="qiskit.circuit.library.iSwapGate.label">
Return gate label
**Return type**
`str`
</Attribute>
### mirror
<Function id="qiskit.circuit.library.iSwapGate.mirror" signature="mirror()">
DEPRECATED: use instruction.reverse\_ops().
**Returns**
**a new instruction with sub-instructions**
reversed.
**Return type**
[qiskit.circuit.Instruction](qiskit.circuit.Instruction "qiskit.circuit.Instruction")
</Function>
### params
<Attribute id="qiskit.circuit.library.iSwapGate.params">
return instruction params.
</Attribute>
### power
<Function id="qiskit.circuit.library.iSwapGate.power" signature="power(exponent)">
Creates a unitary gate as gate^exponent.
**Parameters**
**exponent** (*float*) Gate^exponent
**Returns**
To which to\_matrix is self.to\_matrix^exponent.
**Return type**
[qiskit.extensions.UnitaryGate](qiskit.extensions.UnitaryGate "qiskit.extensions.UnitaryGate")
**Raises**
**CircuitError** If Gate is not unitary
</Function>
### qasm
<Function id="qiskit.circuit.library.iSwapGate.qasm" signature="qasm()">
Return a default OpenQASM string for the instruction.
Derived instructions may override this to print in a different format (e.g. measure q\[0] -> c\[0];).
</Function>
### repeat
<Function id="qiskit.circuit.library.iSwapGate.repeat" signature="repeat(n)">
Creates an instruction with gate repeated n amount of times.
**Parameters**
**n** (*int*) Number of times to repeat the instruction
**Returns**
Containing the definition.
**Return type**
[qiskit.circuit.Instruction](qiskit.circuit.Instruction "qiskit.circuit.Instruction")
**Raises**
**CircuitError** If n \< 1.
</Function>
### reverse\_ops
<Function id="qiskit.circuit.library.iSwapGate.reverse_ops" signature="reverse_ops()">
For a composite instruction, reverse the order of sub-instructions.
This is done by recursively reversing all sub-instructions. It does not invert any gate.
**Returns**
**a new instruction with**
sub-instructions reversed.
**Return type**
[qiskit.circuit.Instruction](qiskit.circuit.Instruction "qiskit.circuit.Instruction")
</Function>
### soft\_compare
<Function id="qiskit.circuit.library.iSwapGate.soft_compare" signature="soft_compare(other)">
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.
**Parameters**
**other** (*instruction*) other instruction.
**Returns**
are self and other equal up to parameter expressions.
**Return type**
bool
</Function>
### to\_matrix
<Function id="qiskit.circuit.library.iSwapGate.to_matrix" signature="to_matrix()">
Return a Numpy.array for the gate unitary matrix.
**Returns**
if the Gate subclass has a matrix definition.
**Return type**
np.ndarray
**Raises**
**CircuitError** If a Gate subclass does not implement this method an exception will be raised when this base class method is called.
</Function>
### unit
<Attribute id="qiskit.circuit.library.iSwapGate.unit">
Get the time unit of duration.
</Attribute>
### validate\_parameter
<Function id="qiskit.circuit.library.iSwapGate.validate_parameter" signature="validate_parameter(parameter)">
Gate parameters should be int, float, or ParameterExpression
</Function>
</Class>