Pauli Gates

The Pauli gates are fundamental single-qubit operations in quantum computing. They correspond to 180° rotations around the X, Y, and Z axes of the Bloch sphere.

Definitions:

  • X gate (bit-flip / NOT):
    • Action: swaps |0⟩ → |1⟩
    • Think: 180° rotation around the Bloch sphere's x-axis
  • Z gate (phase-flip):
    • Action: |0⟩ stays |0⟩, |1⟩ → -|1⟩ (adds a π phase to |1⟩)
    • Think: 180° rotation around the z-axis
  • Y gate (bit + phase flip):
    • Action: |0⟩ → i|1⟩, |1⟩ → -i|0⟩
    • Think: 180° rotation around the y-axis (like X followed by Z, up to a phase)
Pauli Gates Visualization
Visualization of Pauli-X, Pauli-Y, and Pauli-Z gates on their Bloch sphere axes.
XYZ
|0⟩
|1⟩
|-⟩
|+⟩
|-i⟩
|i⟩
Pauli-X
XYZ
|0⟩
|1⟩
|-⟩
|+⟩
|-i⟩
|i⟩
Pauli-Y
XYZ
|0⟩
|1⟩
|-⟩
|+⟩
|-i⟩
|i⟩
Pauli-Z