Physics · Quantum Mechanics

For a spin-1/2 particle placed in a magnetic field B along the y-axis, the Hamiltonian is H = -γBSy = -ωSy, where Sy is the y-component of the spin operator. The state of the system at time t = 0 is |ψ(t=0)> = |+>, where Sz|±> = ±(ℏ/2)|±>. If Sz is measured at a later time t, what is the probability of obtaining the value -ℏ/2?