申論題

15. (20 pts) Consider the spin state of a proton. Recall that the spin operators arewhere i =. Suppose that a static external magnetic field is applied along the y direction, so that the hamiltonian is where B is the magnetic field strength, and is a real constant. Denote the spin up state a and the spin down stateβ as

(c) (2 pts) Suppose that at t = O the proton is at the state Calculate the normalization constant N.