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Glossary

Quantum glossary

Pauli gates (X, Y, Z)

Also: pauli x, pauli y, pauli z, bit flip, phase flip

The three basic single-qubit operations: X flips the bit, Z flips the phase, Y does both.

On the Bloch sphere each is a half-turn about its axis. Any single-qubit error can be written as a combination of them, which is why error-correcting codes only need to catch X and Z errors.

X|0⟩ = |1⟩, Z|1⟩ = −|1⟩, Y = iXZ

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Related terms

  • Bloch sphere — A sphere on which every pure state of a single qubit is one point, and every single-qubit gate is a rotation.
  • Quantum error correction — Encoding quantum information redundantly so errors can be detected and fixed without measuring — and destroying — the data.