This is a conceptual question that has to do with SG devices: You're given amplitudes for an electron for Sz. What will happen if that same electron is passed through a Z-apparatus? And then one in the x-direction? From my understanding the electron then has equal probabilities of spin up & spin down after the Z-apparatus, but the fact that amplitudes were first given in Sz & then were shot through a SG apparatus in the Sz direction confuses me. Any insight?