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.
Measurement
- Shots
How many times a circuit is run to build up statistics from its measurements.
Easy to get wrong: Every quantity estimated from shots carries roughly 1/√N of noise. Doubling precision costs four times the shots.
Seen in use on /workbench
- Standard error
How much an estimate would wobble if you repeated the whole experiment.
Easy to get wrong: A number without one is not a measurement. Two results whose error bars overlap have not been shown to differ.
Seen in use on /leaderboard
- Mitigationalso zero-noise extrapolation, ZNE
Post-processing noisy results to estimate what a noiseless machine would have produced.
Easy to get wrong: It buys accuracy with variance and shots, never for free. Zero-noise extrapolation can make a result worse when the extra uncertainty exceeds the bias it removed.
Seen in use on /workbench
- Expectation value
The average of a measurement over many shots, rather than any single outcome.
Easy to get wrong: Two very different states can share an expectation value. A Bell pair and two independent coin flips give identical single-qubit averages and differ only in their correlations.
Seen in use on /workbench