Yes. X² = I. Apply X twice and you're back to the original state.

Pauli-X Gate (Quantum NOT): Interactive Explainer

Q: Is Pauli-X the same as a quantum NOT?

Yes. Pauli-X flips |0⟩ to |1⟩ and |1⟩ to |0⟩, which is exactly what a NOT gate does in classical logic.

The Pauli-X gate

The quantum NOT. Flips |0⟩ and |1⟩.

Sohum Thakkar · CEO, Qolour

May 8, 2026

The Pauli-X gate swaps |0⟩ with |1⟩. It's the quantum equivalent of a classical NOT gate, and people often call it that. On the Bloch sphere, X is a 180° rotation about the x-axis.

Pauli-Y: 180° rotation about y.
Pauli-Z: 180° rotation about z (phase flip).
Hadamard gate: the gate that creates superposition.
What is a quantum gate? The umbrella concept.

Frequently asked questions

Is Pauli-X the same as a quantum NOT?

Yes. Pauli-X flips |0⟩ ↔ |1⟩, which is exactly the classical NOT operation. The two names are interchangeable.

Is X self-inverse?

Yes. X² = I. Apply X twice and you're back where you started.