Multiple choice
For this circuit, what is the probability that measuring all 5 qubits yields exactly |11111⟩ (qubit 0 leftmost)?
const c = circuit(5); // 1. encode logical |+_L> c.h(0); c.cx(0, 1); c.cx(0, 2); // 2. inject bit-flip on the middle data qubit c.x(1); // 3. syndrome extraction: Z0Z1 -> ancilla 3, Z1Z2 -> ancilla 4 c.cx(0, 3); c.cx(1, 3); c.cx(1, 4); c.cx(2, 4); // 4. correction implied by syndrome (1,1): flip qubit 1 back c.x(1); return c;
Commit your prediction for P(|11111⟩) — then run it.