const c = circuit(2);
// uniform superposition
c.h(0); c.h(1);
// oracle: phase-flip |01⟩ (q0=0, q1=1)
// flip qubit 0 so |01⟩ becomes |11⟩, apply CZ, flip qubit 0 back
c.x(0);
c.cz(0, 1);
c.x(0);
// diffuser: 2|s><s| - I = H X CZ X H
c.h(0); c.h(1);
c.x(0); c.x(1);
c.cz(0, 1);
c.x(0); c.x(1);
c.h(0); c.h(1);
return c;