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
- Stabilizer
A measurement a code makes repeatedly that returns the same answer as long as nothing has gone wrong.
Easy to get wrong: Stabilizers never measure the stored data — doing so would destroy the superposition. They only report whether they were disturbed.
Seen in use on /qec/syndromes
- Syndrome
The pattern of which stabilizers were disturbed: the only information a decoder gets about an error.
Easy to get wrong: An all-zero syndrome does not mean nothing happened. An error heavy enough to commute with every stabilizer is applied silently, which is exactly what a code's distance limits.
Seen in use on /qec/syndromes
- Decoder
The algorithm that reads a syndrome and decides what correction to apply.
Easy to get wrong: A decoder succeeds when its guess differs from the real error by a stabilizer, not when it guesses correctly. Scoring by exact match reports failures on codes that in fact corrected everything.
Seen in use on /decoders