Deriving the mean energy.

  1. A one dimensional quantum harmonic oscillator is initially in the state, nx, = A (—nk/r4)11 4 ( .17u x +1)2 e-nt (a) Derive the mean energy. (E) of the osvillator. (b) Write down the time evolved wave function, tli(x, t). (c) Now derive the mean momentum of the oscillator, (p).
    (6 Marks)
  2. Consider a free particle anywhere on the x-axis given by the wave function, 111(x) - a o E C and 8> 0. (a) Compute and sketch the wave function in the momentum space, ir(k). (b) Does the uncertainty product, Az Ak depend on the parameters, a and 0? Prove this. (6 Marks)
  3. Consider the delta function barrier, V(x) = a 6(x), a > 0 (a) Do bound states exist? Explain your answer. (b) Derive the reflection coefficient R and sketch it as a function of particle energy. (4 Marks) 4. Let A be a Hermitian operator with eigenkets (1a1)} corresponding to distinct eigenvalues (a) Prove that
    is a null operator. (b) Explain the physical significance of
    H(A -
    rr (A - ai) isi (a • - ai)
    Hint: It gets easy if you take A = 5: of a spin 1/2 system.
    (4 Marks)