Multiple choice
After this circuit, what is P(|1011⟩) for the whole 4-qubit register measured together (qubit 0 leftmost)?
const c = circuit(4); c.x(0); c.h(1); c.cx(1, 2); // Entangle the control into A's ancilla, send the parity across the link. c.cx(0, 1); // Entangle B's ancilla into the target. c.cx(2, 3); // Feed-forward corrections (deferred-measurement form): c.cx(1, 3); // X correction on the target conditioned on q1 c.h(2); c.cz(2, 0); // Z correction on the control conditioned on q2 c.measure(); return c;
Commit your prediction for P(|1011⟩) — then run it.