Multiple choice
After this circuit, what is P(|101⟩) for the whole 3-qubit register measured together (qubit 0 leftmost)?
const c = circuit(3); // 1. Encode |+_L>. c.h(0); c.cx(0, 1); c.cx(0, 2); // 2. Inject an X error on qubit 2. c.x(2); // 3. Decode (CNOT is self-inverse). c.cx(0, 1); c.cx(0, 2); // 4. Coherent majority correction onto the data qubit. c.ccx(2, 1, 0); return c;
Commit your prediction for P(|101⟩) — then run it.