---
title: OrGate (v1.4)
description: API reference for qiskit.circuit.library.OrGate in qiskit v1.4
source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/qiskit/1.4/qiskit.circuit.library.OrGate
---

# OrGate

*class* `qiskit.circuit.library.OrGate(num_variable_qubits, flags=None)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.4/qiskit/circuit/library/boolean_logic/quantum_or.py#L110-L206)

Bases: [`Gate`](/docs/api/qiskit/1.4/qiskit.circuit.Gate "qiskit.circuit.gate.Gate")

A gate representing the logical OR operation on a number of qubits.

For the OR operation the state $|1\rangle$ is interpreted as `True`. The result qubit is flipped, if the state of any variable qubit is `True`. The OR is implemented using a multi-open-controlled X gate (i.e. flips if the state is $|0\rangle$) and applying an X gate on the result qubit. Using a list of flags, qubits can be skipped or negated.

The OrGate gate without special flags:

![Diagram illustrating the previously described circuit.](https://eu-de.quantum.cloud.ibm.com/docs/images/api/qiskit/1.4/qiskit-circuit-library-OrGate-1.avif)

Using flags we can negate qubits or skip them. For instance, if we have 5 qubits and want to return `True` if the first qubit is `False` or one of the last two are `True` we use the flags `[-1, 0, 0, 1, 1]`.

![Diagram illustrating the previously described circuit.](https://eu-de.quantum.cloud.ibm.com/docs/images/api/qiskit/1.4/qiskit-circuit-library-OrGate-2.avif)

**Parameters**

- **num\_variable\_qubits** ([*int*](https://docs.python.org/3/library/functions.html#int)) – The qubits of which the OR is computed. The result will be written into an additional result qubit.
- **flags** ([*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[*[*int*](https://docs.python.org/3/library/functions.html#int)*] | None*) – A list of +1/0/-1 marking negations or omissions of qubits.

## Attributes

### base\_class

Get the base class of this instruction. This is guaranteed to be in the inheritance tree of `self`.

The “base class” of an instruction is the lowest class in its inheritance tree that the object should be considered entirely compatible with for \_all\_ circuit applications. This typically means that the subclass is defined purely to offer some sort of programmer convenience over the base class, and the base class is the “true” class for a behavioral perspective. In particular, you should *not* override [`base_class`](#qiskit.circuit.library.OrGate.base_class "qiskit.circuit.library.OrGate.base_class") if you are defining a custom version of an instruction that will be implemented differently by hardware, such as an alternative measurement strategy, or a version of a parametrized gate with a particular set of parameters for the purposes of distinguishing it in a [`Target`](/docs/api/qiskit/1.4/qiskit.transpiler.Target "qiskit.transpiler.Target") from the full parametrized gate.

This is often exactly equivalent to `type(obj)`, except in the case of singleton instances of standard-library instructions. These singleton instances are special subclasses of their base class, and this property will return that base. For example:

```python
>>> isinstance(XGate(), XGate)
True
>>> type(XGate()) is XGate
False
>>> XGate().base_class is XGate
True
```

In general, you should not rely on the precise class of an instruction; within a given circuit, it is expected that `Instruction.name` should be a more suitable discriminator in most situations.

### condition

The classical condition on the instruction.

> **Deprecated since version 1.3.0**
>
> The property `qiskit.circuit.instruction.Instruction.condition` is deprecated as of qiskit 1.3.0. It will be removed in 2.0.0.

### condition\_bits

Get Clbits in condition.

> **Deprecated since version 1.3.0**
>
> The property `qiskit.circuit.instruction.Instruction.condition_bits` is deprecated as of qiskit 1.3.0. It will be removed in 2.0.0.

### decompositions

Get the decompositions of the instruction from the SessionEquivalenceLibrary.

### definition

Return definition in terms of other basic gates.

### duration

Get the duration.

> **Deprecated since version 1.3.0**
>
> The property `qiskit.circuit.instruction.Instruction.duration` is deprecated as of qiskit 1.3.0. It will be removed in Qiskit 2.0.0.

### label

Return instruction label

### mutable

Is this instance is a mutable unique instance or not.

If this attribute is `False` the gate instance is a shared singleton and is not mutable.

### name

Return the name.

### num\_clbits

Return the number of clbits.

### num\_qubits

Return the number of qubits.

### params

The parameters of this `Instruction`. Ideally these will be gate angles.

### unit

Get the time unit of duration.

> **Deprecated since version 1.3.0**
>
> The property `qiskit.circuit.instruction.Instruction.unit` is deprecated as of qiskit 1.3.0. It will be removed in Qiskit 2.0.0.

## Methods

### inverse

`inverse(annotated=False)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.4/qiskit/circuit/library/boolean_logic/quantum_or.py#L187-L199)

Return inverted OR gate (itself).

**Parameters**

**annotated** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – when set to `True`, this is typically used to return an [`AnnotatedOperation`](/docs/api/qiskit/1.4/qiskit.circuit.AnnotatedOperation "qiskit.circuit.AnnotatedOperation") with an inverse modifier set instead of a concrete [`Gate`](/docs/api/qiskit/1.4/qiskit.circuit.Gate "qiskit.circuit.Gate"). However, for this class this argument is ignored as this gate is self-inverse.

**Returns**

inverse gate (self-inverse).

**Return type**

[OrGate](#qiskit.circuit.library.OrGate "qiskit.circuit.library.OrGate")