Fixing Fragile Qubits

Quantum error correction

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Error correction spreads one logical qubit across many physical qubits.
• A 3-qubit code turns error rate $p$ into about $3p^2$, if $p < \frac12$.
• Parity (syndrome) measurements find errors without reading the data.

Steps

1. Noise everywhere
2. Three are safer than one
3. A big improvement
4. Checking without looking
5. The overhead
6. Below threshold