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---
title: RCCXGate (v0.26)
description: API reference for qiskit.circuit.library.RCCXGate in qiskit v0.26
in_page_toc_min_heading_level: 1
python_api_type: class
python_api_name: qiskit.circuit.library.RCCXGate
---
<span id="qiskit-circuit-library-rccxgate" />
# qiskit.circuit.library.RCCXGate
<Class id="qiskit.circuit.library.RCCXGate" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.17/qiskit/circuit/library/standard_gates/x.py" signature="RCCXGate(label=None)" modifiers="class">
The simplified Toffoli gate, also referred to as Margolus gate.
The simplified Toffoli gate implements the Toffoli gate up to relative phases. This implementation requires three CX gates which is the minimal amount possible, as shown in [https://arxiv.org/abs/quant-ph/0312225](https://arxiv.org/abs/quant-ph/0312225). Note, that the simplified Toffoli is not equivalent to the Toffoli. But can be used in places where the Toffoli gate is uncomputed again.
This concrete implementation is from [https://arxiv.org/abs/1508.03273](https://arxiv.org/abs/1508.03273), the dashed box of Fig. 3.
Create a new simplified CCX gate.
### \_\_init\_\_
<Function id="qiskit.circuit.library.RCCXGate.__init__" signature="__init__(label=None)">
Create a new simplified CCX gate.
</Function>
## Methods
| | |
| ------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------ |
| [`__init__`](#qiskit.circuit.library.RCCXGate.__init__ "qiskit.circuit.library.RCCXGate.__init__")(\[label]) | Create a new simplified CCX gate. |
| [`add_decomposition`](#qiskit.circuit.library.RCCXGate.add_decomposition "qiskit.circuit.library.RCCXGate.add_decomposition")(decomposition) | Add a decomposition of the instruction to the SessionEquivalenceLibrary. |
| [`assemble`](#qiskit.circuit.library.RCCXGate.assemble "qiskit.circuit.library.RCCXGate.assemble")() | Assemble a QasmQobjInstruction |
| [`broadcast_arguments`](#qiskit.circuit.library.RCCXGate.broadcast_arguments "qiskit.circuit.library.RCCXGate.broadcast_arguments")(qargs, cargs) | Validation and handling of the arguments and its relationship. |
| [`c_if`](#qiskit.circuit.library.RCCXGate.c_if "qiskit.circuit.library.RCCXGate.c_if")(classical, val) | Add classical condition on register classical and value val. |
| [`control`](#qiskit.circuit.library.RCCXGate.control "qiskit.circuit.library.RCCXGate.control")(\[num\_ctrl\_qubits, label, ctrl\_state]) | Return controlled version of gate. |
| [`copy`](#qiskit.circuit.library.RCCXGate.copy "qiskit.circuit.library.RCCXGate.copy")(\[name]) | Copy of the instruction. |
| [`inverse`](#qiskit.circuit.library.RCCXGate.inverse "qiskit.circuit.library.RCCXGate.inverse")() | Invert this instruction. |
| [`is_parameterized`](#qiskit.circuit.library.RCCXGate.is_parameterized "qiskit.circuit.library.RCCXGate.is_parameterized")() | Return True .IFF. |
| [`mirror`](#qiskit.circuit.library.RCCXGate.mirror "qiskit.circuit.library.RCCXGate.mirror")() | DEPRECATED: use instruction.reverse\_ops(). |
| [`power`](#qiskit.circuit.library.RCCXGate.power "qiskit.circuit.library.RCCXGate.power")(exponent) | Creates a unitary gate as gate^exponent. |
| [`qasm`](#qiskit.circuit.library.RCCXGate.qasm "qiskit.circuit.library.RCCXGate.qasm")() | Return a default OpenQASM string for the instruction. |
| [`repeat`](#qiskit.circuit.library.RCCXGate.repeat "qiskit.circuit.library.RCCXGate.repeat")(n) | Creates an instruction with gate repeated n amount of times. |
| [`reverse_ops`](#qiskit.circuit.library.RCCXGate.reverse_ops "qiskit.circuit.library.RCCXGate.reverse_ops")() | For a composite instruction, reverse the order of sub-instructions. |
| [`soft_compare`](#qiskit.circuit.library.RCCXGate.soft_compare "qiskit.circuit.library.RCCXGate.soft_compare")(other) | Soft comparison between gates. |
| [`to_matrix`](#qiskit.circuit.library.RCCXGate.to_matrix "qiskit.circuit.library.RCCXGate.to_matrix")() | Return a Numpy.array for the gate unitary matrix. |
| [`validate_parameter`](#qiskit.circuit.library.RCCXGate.validate_parameter "qiskit.circuit.library.RCCXGate.validate_parameter")(parameter) | Gate parameters should be int, float, or ParameterExpression |
## Attributes
| | |
| -------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------- |
| [`decompositions`](#qiskit.circuit.library.RCCXGate.decompositions "qiskit.circuit.library.RCCXGate.decompositions") | Get the decompositions of the instruction from the SessionEquivalenceLibrary. |
| [`definition`](#qiskit.circuit.library.RCCXGate.definition "qiskit.circuit.library.RCCXGate.definition") | Return definition in terms of other basic gates. |
| [`duration`](#qiskit.circuit.library.RCCXGate.duration "qiskit.circuit.library.RCCXGate.duration") | Get the duration. |
| [`label`](#qiskit.circuit.library.RCCXGate.label "qiskit.circuit.library.RCCXGate.label") | Return gate label |
| [`params`](#qiskit.circuit.library.RCCXGate.params "qiskit.circuit.library.RCCXGate.params") | return instruction params. |
| [`unit`](#qiskit.circuit.library.RCCXGate.unit "qiskit.circuit.library.RCCXGate.unit") | Get the time unit of duration. |
### add\_decomposition
<Function id="qiskit.circuit.library.RCCXGate.add_decomposition" signature="add_decomposition(decomposition)">
Add a decomposition of the instruction to the SessionEquivalenceLibrary.
</Function>
### assemble
<Function id="qiskit.circuit.library.RCCXGate.assemble" signature="assemble()">
Assemble a QasmQobjInstruction
**Return type**
`Instruction`
</Function>
### broadcast\_arguments
<Function id="qiskit.circuit.library.RCCXGate.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.RCCXGate.c_if" signature="c_if(classical, val)">
Add classical condition on register classical and value val.
</Function>
### control
<Function id="qiskit.circuit.library.RCCXGate.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.RCCXGate.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.RCCXGate.decompositions">
Get the decompositions of the instruction from the SessionEquivalenceLibrary.
</Attribute>
### definition
<Attribute id="qiskit.circuit.library.RCCXGate.definition">
Return definition in terms of other basic gates.
</Attribute>
### duration
<Attribute id="qiskit.circuit.library.RCCXGate.duration">
Get the duration.
</Attribute>
### inverse
<Function id="qiskit.circuit.library.RCCXGate.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.RCCXGate.is_parameterized" signature="is_parameterized()">
Return True .IFF. instruction is parameterized else False
</Function>
### label
<Attribute id="qiskit.circuit.library.RCCXGate.label">
Return gate label
**Return type**
`str`
</Attribute>
### mirror
<Function id="qiskit.circuit.library.RCCXGate.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.RCCXGate.params">
return instruction params.
</Attribute>
### power
<Function id="qiskit.circuit.library.RCCXGate.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.RCCXGate.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.RCCXGate.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.RCCXGate.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.RCCXGate.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.RCCXGate.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.RCCXGate.unit">
Get the time unit of duration.
</Attribute>
### validate\_parameter
<Function id="qiskit.circuit.library.RCCXGate.validate_parameter" signature="validate_parameter(parameter)">
Gate parameters should be int, float, or ParameterExpression
</Function>
</Class>