in this problem we are interested in the time-evolution of the states in the infinite square...

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Physics

in this problem we are interested in the time-evolution of thestates in the infinite square potential well. The time-independentstationary state wave functions are denoted as ψn(x) (n = 1, 2, . ..).

(a) We know that the probability distribution for the particlein a stationary state is time-independent. Let us now prepare, attime t = 0, our system in a non-stationary state

Ψ(x, 0) = (1/√( 2)) (ψ1(x) + ψ2(x)).

Study the time-evolution of the probability density |Ψ(x, t)|^2for this state. Is it periodic in the sense that after some time Tit will return to its initial state at t = 0? If so, what is T?Sketch, better yet plot (by using some software), |Ψ(x, t)|^2 for 3or 4 moments of time t between 0 and T that would nicely displaythe qualitative features of the changes, if any.

(b) Let us now prepare the system in some arbitrarynon-stationary state Ψ(x, 0). Is it true that after some time T,the wave function will always return to its original spatialbehavior, that is,

Ψ(x, T) = Ψ(x, 0)

(perhaps with accuracy to an inconsequential overall phasefactor)? If so, what is this quantum revival time T? Compare to(a). And why do you think it was possible to have it in this systemfor an arbitrary state?

(c) Think now about the revival time for a classicalparticle of energy E bouncing between the walls. Assuming thepositive answer to (b), if we were to compare the classical revivalbehavior to the quantum revival behavior, when these times would beequal?

Need help with Part C!

Answer & Explanation Solved by verified expert
3.8 Ratings (685 Votes)
c The classical revival time is just the time period of aclassical particle moving in a box of length L with velocity vTo return to the same point the particle has to cover 2Ldistance with velocity v The classical time period is thenp mv is the momentumAlso the total    See Answer
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