# MCXGate

*class *`MCXGate(num_ctrl_qubits, label=None, ctrl_state=None, _name='mcx')`

Bases: `qiskit.circuit.controlledgate.ControlledGate`

The general, multi-controlled X gate.

Can be applied to a `QuantumCircuit`

with the `mcx()`

method.

Create new MCX gate.

## Methods Defined Here

### control

`MCXGate.control(num_ctrl_qubits=1, label=None, ctrl_state=None)`

Return a multi-controlled-X gate with more control lines.

**Parameters**

**num_ctrl_qubits**(*int*) – number of control qubits.**label**(*str or None*) – An optional label for the gate [Default: None]**ctrl_state**(*int or str or None*) – control state expressed as integer, string (e.g. ‘110’), or None. If None, use all 1s.

**Returns**

controlled version of this gate.

**Return type**

### get_num_ancilla_qubits

*static *`MCXGate.get_num_ancilla_qubits(num_ctrl_qubits, mode='noancilla')`

Get the number of required ancilla qubits without instantiating the class.

This staticmethod might be necessary to check the number of ancillas before creating the gate, or to use the number of ancillas in the initialization.

**Return type**

`int`

### inverse

`MCXGate.inverse()`

Invert this gate. The MCX is its own inverse.

## Attributes

### condition_bits

### ctrl_state

Return the control state of the gate as a decimal integer.

**Return type**

`int`

### decompositions

Get the decompositions of the instruction from the SessionEquivalenceLibrary.

### definition

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.

**Return type**

`List`

### duration

Get the duration.

### label

Return instruction label

**Return type**

`str`

### name

Get name of gate. If the gate has open controls the gate name will become:

<original_name_o<ctrl_state>

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.

**Return type**

`str`

### num_ancilla_qubits

The number of ancilla qubits.

### num_clbits

Return the number of clbits.

### num_ctrl_qubits

Get number of control qubits.

**Returns**

The number of control qubits for the gate.

**Return type**

int

### num_qubits

Return the number of qubits.

### params

Get parameters from base_gate.

**Returns**

List of gate parameters.

**Return type**

list

**Raises**

**CircuitError** – Controlled gate does not define a base gate

### unit

Get the time unit of duration.