419 lines
15 KiB
Plaintext
419 lines
15 KiB
Plaintext
---
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title: ControlledGate
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description: API reference for qiskit.circuit.ControlledGate
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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.ControlledGate
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---
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# ControlledGate
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<Class id="qiskit.circuit.ControlledGate" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.25/qiskit/circuit/controlledgate.py" signature="qiskit.circuit.ControlledGate(name, num_qubits, params, label=None, num_ctrl_qubits=1, definition=None, ctrl_state=None, base_gate=None)" modifiers="class">
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Bases: [`Gate`](qiskit.circuit.Gate "qiskit.circuit.gate.Gate")
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Controlled unitary gate.
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Create a new ControlledGate. In the new gate the first `num_ctrl_qubits` of the gate are the controls.
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**Parameters**
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* **name** ([*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.12)")) – The name of the gate.
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* **num\_qubits** ([*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.12)")) – The number of qubits the gate acts on.
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* **params** ([*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.12)")) – A list of parameters for the gate.
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* **label** (*Optional\[*[*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.12)")*]*) – An optional label for the gate.
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* **num\_ctrl\_qubits** (*Optional\[*[*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.12)")*]*) – Number of control qubits.
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* **definition** (*Optional\['QuantumCircuit']*) – A list of gate rules for implementing this gate. The elements of the list are tuples of ([`Gate()`](qiskit.circuit.Gate "qiskit.circuit.Gate"), \[qubit\_list], \[clbit\_list]).
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* **ctrl\_state** (*Optional\[Union\[*[*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.12)")*,* [*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.12)")*]]*) – The control state in decimal or as a bitstring (e.g. ‘111’). If specified as a bitstring the length must equal num\_ctrl\_qubits, MSB on left. If None, use 2\*\*num\_ctrl\_qubits-1.
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* **base\_gate** (*Optional\[*[*Gate*](qiskit.circuit.Gate "qiskit.circuit.Gate")*]*) – Gate object to be controlled.
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**Raises**
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* [**CircuitError**](circuit#qiskit.circuit.CircuitError "qiskit.circuit.CircuitError") – If `num_ctrl_qubits` >= `num_qubits`.
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* [**CircuitError**](circuit#qiskit.circuit.CircuitError "qiskit.circuit.CircuitError") – ctrl\_state \< 0 or ctrl\_state > 2\*\*num\_ctrl\_qubits.
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Examples:
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Create a controlled standard gate and apply it to a circuit.
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```python
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from qiskit import QuantumCircuit, QuantumRegister
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from qiskit.circuit.library.standard_gates import HGate
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qr = QuantumRegister(3)
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qc = QuantumCircuit(qr)
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c3h_gate = HGate().control(2)
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qc.append(c3h_gate, qr)
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qc.draw('mpl')
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```
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Create a controlled custom gate and apply it to a circuit.
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```python
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from qiskit import QuantumCircuit, QuantumRegister
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from qiskit.circuit.library.standard_gates import HGate
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qc1 = QuantumCircuit(2)
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qc1.x(0)
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qc1.h(1)
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custom = qc1.to_gate().control(2)
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qc2 = QuantumCircuit(4)
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qc2.append(custom, [0, 3, 1, 2])
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qc2.draw('mpl')
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```
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## Attributes
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### condition\_bits
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<Attribute id="qiskit.circuit.ControlledGate.condition_bits">
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Get Clbits in condition.
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</Attribute>
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### ctrl\_state
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<Attribute id="qiskit.circuit.ControlledGate.ctrl_state">
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Return the control state of the gate as a decimal integer.
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</Attribute>
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### decompositions
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<Attribute id="qiskit.circuit.ControlledGate.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.ControlledGate.definition">
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Return definition in terms of other basic gates. If the gate has open controls, as determined from self.ctrl\_state, the returned definition is conjugated with X without changing the internal \_definition.
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</Attribute>
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### duration
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<Attribute id="qiskit.circuit.ControlledGate.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.ControlledGate.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.ControlledGate.name">
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Get name of gate. If the gate has open controls the gate name will become:
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> \<original\_name\_o\<ctrl\_state>
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where \<original\_name> is the gate name for the default case of closed control qubits and \<ctrl\_state> is the integer value of the control state for the gate.
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</Attribute>
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### num\_clbits
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<Attribute id="qiskit.circuit.ControlledGate.num_clbits">
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Return the number of clbits.
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</Attribute>
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### num\_ctrl\_qubits
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<Attribute id="qiskit.circuit.ControlledGate.num_ctrl_qubits">
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Get number of control qubits.
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**Returns**
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The number of control qubits for the gate.
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**Return type**
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[int](https://docs.python.org/3/library/functions.html#int "(in Python v3.12)")
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</Attribute>
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### num\_qubits
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<Attribute id="qiskit.circuit.ControlledGate.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.ControlledGate.params">
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Get parameters from base\_gate.
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**Returns**
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List of gate parameters.
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**Return type**
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[list](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.12)")
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**Raises**
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[**CircuitError**](circuit#qiskit.circuit.CircuitError "qiskit.circuit.CircuitError") – Controlled gate does not define a base gate
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</Attribute>
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### unit
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<Attribute id="qiskit.circuit.ControlledGate.unit">
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Get the time unit of duration.
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</Attribute>
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## Methods
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### add\_decomposition
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<Function id="qiskit.circuit.ControlledGate.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.ControlledGate.assemble" signature="assemble()">
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Assemble a QasmQobjInstruction
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</Function>
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### broadcast\_arguments
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<Function id="qiskit.circuit.ControlledGate.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*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.12)")) – List of quantum bit arguments.
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* **cargs** ([*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.12)")) – List of classical bit arguments.
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**Returns**
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A tuple with single arguments.
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**Raises**
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[**CircuitError**](circuit#qiskit.circuit.CircuitError "qiskit.circuit.CircuitError") – If the input is not valid. For example, the number of arguments does not match the gate expectation.
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**Return type**
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[*Iterable*](https://docs.python.org/3/library/typing.html#typing.Iterable "(in Python v3.12)")\[[tuple](https://docs.python.org/3/library/stdtypes.html#tuple "(in Python v3.12)")\[[list](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.12)"), [list](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.12)")]]
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</Function>
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### c\_if
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<Function id="qiskit.circuit.ControlledGate.c_if" signature="c_if(classical, val)">
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Set a classical equality condition on this instruction between the register or cbit `classical` and value `val`.
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<Admonition title="Note" type="note">
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This is a setter method, not an additive one. Calling this multiple times will silently override any previously set condition; it does not stack.
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</Admonition>
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</Function>
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### control
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<Function id="qiskit.circuit.ControlledGate.control" signature="control(num_ctrl_qubits=1, label=None, ctrl_state=None)">
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Return controlled version of gate. See [`ControlledGate`](#qiskit.circuit.ControlledGate "qiskit.circuit.ControlledGate") for usage.
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**Parameters**
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* **num\_ctrl\_qubits** ([*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.12)")) – number of controls to add to gate (default: `1`)
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* **label** ([*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.12)") *| None*) – optional gate label
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* **ctrl\_state** ([*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.12)") *|*[*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.12)") *| None*) – The control state in decimal or as a bitstring (e.g. `'111'`). If `None`, use `2**num_ctrl_qubits-1`.
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**Returns**
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Controlled version of gate. This default algorithm uses `num_ctrl_qubits-1` ancilla qubits so returns a gate of size `num_qubits + 2*num_ctrl_qubits - 1`.
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**Return type**
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[qiskit.circuit.ControlledGate](#qiskit.circuit.ControlledGate "qiskit.circuit.ControlledGate")
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**Raises**
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[**QiskitError**](exceptions#qiskit.exceptions.QiskitError "qiskit.exceptions.QiskitError") – unrecognized mode or invalid ctrl\_state
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</Function>
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### copy
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<Function id="qiskit.circuit.ControlledGate.copy" signature="copy(name=None)">
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Copy of the instruction.
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**Parameters**
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**name** ([*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.12)")) – 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 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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### inverse
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<Function id="qiskit.circuit.ControlledGate.inverse" signature="inverse()">
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Invert this gate by calling inverse on the base gate.
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**Return type**
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[*ControlledGate*](#qiskit.circuit.ControlledGate "qiskit.circuit.controlledgate.ControlledGate")
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</Function>
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### is\_parameterized
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<Function id="qiskit.circuit.ControlledGate.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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### power
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<Function id="qiskit.circuit.ControlledGate.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*](https://docs.python.org/3/library/functions.html#float "(in Python v3.12)")) – 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**](circuit#qiskit.circuit.CircuitError "qiskit.circuit.CircuitError") – If Gate is not unitary
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</Function>
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### qasm
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<Function id="qiskit.circuit.ControlledGate.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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<Admonition title="Deprecated since version 0.25.0" type="danger">
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The method `qiskit.circuit.instruction.Instruction.qasm()` is deprecated as of qiskit-terra 0.25.0. It will be removed no earlier than 3 months after the release date. Correct exporting to OpenQASM 2 is the responsibility of a larger exporter; it cannot safely be done on an object-by-object basis without context. No replacement will be provided, because the premise is wrong.
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</Admonition>
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</Function>
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### repeat
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<Function id="qiskit.circuit.ControlledGate.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*](https://docs.python.org/3/library/functions.html#int "(in Python v3.12)")) – 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**](circuit#qiskit.circuit.CircuitError "qiskit.circuit.CircuitError") – If n \< 1.
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</Function>
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### reverse\_ops
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<Function id="qiskit.circuit.ControlledGate.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.ControlledGate.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](https://docs.python.org/3/library/functions.html#bool "(in Python v3.12)")
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</Function>
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### to\_matrix
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<Function id="qiskit.circuit.ControlledGate.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**](circuit#qiskit.circuit.CircuitError "qiskit.circuit.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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### validate\_parameter
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<Function id="qiskit.circuit.ControlledGate.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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