Suppose in a magnetic field which is in the z-direction we send a magnet with its N-pole directed in the x-direction. We know the magnet would rotate and become in line with the magnetic field. However, if we send a pure spin state \(\displaystyle |S_x,+>\) it can depart in the two opposite directions +z and -z, with the same probability without changing its state. If we simulate \(\displaystyle |S_x,+>\) with a magnet which its N-pole directed in the x-direction then we expect the spin also to rotate, in other words, change its state to \(\displaystyle |S_z,+>\). Could anyone please help me where I am wrong?