const c = circuit(3);
// prepare periodic state: period 2, nonzero at {0,2,4,6}
c.h(0); c.h(1);
// 3-qubit QFT
c.h(0);
c.cp(Math.PI / 2, 1, 0);
c.cp(Math.PI / 4, 2, 0);
c.h(1);
c.cp(Math.PI / 2, 2, 1);
c.h(2);
// bit-reversal SWAPs
c.swap(0, 2);
// measure all qubits
c.measure();
return c;