Quantum Mechanics: Concepts and Applications · Problem 3.21

One-Dimensional Problems — Nouredine Zettili

Physics — Quantum Mechanics · time-evolution-energy-csco

Problem

Consider a system which is initially in a state ∣ψ(0)⟩|\psi(0)\rangle and having a Hamiltonian H^\hat{H}, where ∣ψ(0)⟩=(4−i−2+5i3+2i),H=12(0−i0i33030).|\psi(0)\rangle = \begin{pmatrix} 4-i \\ -2+5i \\ 3+2i \end{pmatrix}, \quad H = \frac{1}{\sqrt{2}} \begin{pmatrix} 0 & -i & 0 \\ i & 3 & 3 \\ 0 & 3 & 0 \end{pmatrix}. (a) If a measurement of HH is carried out, what values will we obtain and with what probabilities? (b) Find the state of the system at a later time tt; you may need to expand ∣ψ(0)⟩|\psi(0)\rangle in terms of the eigenvectors of HH. (c) Find the total energy of the system at time t=0t = 0 and any later time tt; are these values different? (d) Does H^\hat{H} form a complete set of commuting operators?

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