# CZGate

*class *`CZGate(label=None, ctrl_state=None)`

Bases: `qiskit.circuit.controlledgate.ControlledGate`

Controlled-Z gate.

This is a Clifford and symmetric gate.

Can be applied to a `QuantumCircuit`

with the `cz()`

method.

**Circuit symbol:**

```
q_0: ─■─
│
q_1: ─■─
```

**Matrix representation:**

In the computational basis, this gate flips the phase of the target qubit if the control qubit is in the $|1\rangle$ state.

Create new CZ gate.

## Methods Defined Here

### inverse

`CZGate.inverse()`

Return inverted CZ gate (itself).

## 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_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.