A two-level system with states a and , whose energy levels differ by Eb - Ea = hwo, is initially in the state a. It is then exposed to two short pulses, V'(t) = Vo[8(t) + 8(t - T)], (3) where T> 0 is a constant. Using first-order time- dependent perturbation theory, derive the probability that the system is in the state , after the second pulse. What choice of T maximizes the probability?