1.Show that one gets a 50% : 50% probability for deflection up and down in a y-Stern Gerlach measurement when atoms that are preselected as +x atoms or -x atoms are used as a source. What kind of the equation is it? Do we just need to find the coefficients and square them? 2.A source produces atoms is using z-basis as a matrix A (1 i) and moving along y-axis. then we know a magnetic field is applied to the atoms in +y direction to rotate the dipole moment by an angle(a) and we know the rotation matrix B (about a). For the mathematical description of the state after rotation is AB. Is that right? Thanks a lot.