const s = 0.5;
// Ground state of H(s) = -(1-s)X - sZ has Bloch vector along (1-s, 0, s).
// RY(theta)|0> produces Bloch (sin theta, 0, cos theta), so:
const theta = Math.atan2(1 - s, s);
const c = circuit(1);
c.ry(theta, 0);
return c;