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
- Surface code
The most studied way to build a logical qubit, laying physical qubits on a two-dimensional grid where only neighbours interact.
Easy to get wrong: It only suppresses errors below its threshold. Above that, adding more qubits makes the logical error rate worse, not better.
Seen in use on /qec
- Logical error rate
How often the protected information is corrupted despite error correction, per round or per computation.
Easy to get wrong: Zero observed failures is not a rate of zero. Zero failures in 10,000 shots bounds the rate below roughly 3.8×10⁻⁴ and says nothing about whether it is 10⁻⁵ or 3×10⁻⁴.
Seen in use on /leaderboard