147 lines
3.7 KiB
Plaintext
147 lines
3.7 KiB
Plaintext
---
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title: MCXRecursive
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description: API reference for qiskit.circuit.library.MCXRecursive
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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.MCXRecursive
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---
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# MCXRecursive
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<Class id="qiskit.circuit.library.MCXRecursive" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.19/qiskit/circuit/library/standard_gates/x.py" signature="MCXRecursive(num_ctrl_qubits, label=None, ctrl_state=None)" modifiers="class">
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Bases: `qiskit.circuit.library.standard_gates.x.MCXGate`
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Implement the multi-controlled X gate using recursion.
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Using a single ancilla qubit, the multi-controlled X gate is recursively split onto four sub-registers. This is done until we reach the 3- or 4-controlled X gate since for these we have a concrete implementation that do not require ancillas.
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Create new MCX gate.
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## Methods Defined Here
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### get\_num\_ancilla\_qubits
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<Function id="qiskit.circuit.library.MCXRecursive.get_num_ancilla_qubits" signature="MCXRecursive.get_num_ancilla_qubits(num_ctrl_qubits, mode='recursion')" modifiers="static">
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Get the number of required ancilla qubits.
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</Function>
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### inverse
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<Function id="qiskit.circuit.library.MCXRecursive.inverse" signature="MCXRecursive.inverse()">
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Invert this gate. The MCX is its own inverse.
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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.MCXRecursive.condition_bits">
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Get Clbits in condition.
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**Return type**
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`List`\[`Clbit`]
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</Attribute>
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### ctrl\_state
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<Attribute id="qiskit.circuit.library.MCXRecursive.ctrl_state">
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Return the control state of the gate as a decimal integer.
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**Return type**
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`int`
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</Attribute>
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### decompositions
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<Attribute id="qiskit.circuit.library.MCXRecursive.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.MCXRecursive.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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**Return type**
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`List`
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</Attribute>
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### duration
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<Attribute id="qiskit.circuit.library.MCXRecursive.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.MCXRecursive.label">
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Return instruction label
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**Return type**
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`str`
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</Attribute>
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### name
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<Attribute id="qiskit.circuit.library.MCXRecursive.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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**Return type**
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`str`
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</Attribute>
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### num\_ancilla\_qubits
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<Attribute id="qiskit.circuit.library.MCXRecursive.num_ancilla_qubits">
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The number of ancilla qubits.
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</Attribute>
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### num\_ctrl\_qubits
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<Attribute id="qiskit.circuit.library.MCXRecursive.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
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</Attribute>
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### params
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<Attribute id="qiskit.circuit.library.MCXRecursive.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
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**Raises**
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**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.library.MCXRecursive.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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