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;