Glossary
Every technical term this platform uses, with what it means and — the part that is harder to find elsewhere — the mistake it prevents. On this subject the intuitive reading is often the wrong one, so each entry says what a reader would otherwise get wrong.
Error correction
- Logical qubit
One qubit's worth of protected information, stored across many physical qubits so that errors can be detected and undone.
Easy to get wrong: The count of logical qubits is not the size of the machine. A single logical qubit at code distance 11 occupies 242 physical qubits, and routing space and magic-state factories are on top of that.
Seen in use on /workbench
- Code distancealso distance, d
The smallest number of physical errors that can corrupt the encoded information without being noticed.
Easy to get wrong: Distance d corrects only (d−1)/2 errors, not d. A distance-3 code corrects one error and *miscorrects* two — the correction itself introduces the failure.
Seen in use on /qec/syndromes