Advanced Quantum Mechanics Problems
Set 1
1) An electron of mass m is confined in a container with box boundary conditions of length
L1 in the x direction, periodic boundary conditions of length L2 in the y direction and a
Simple Harmonic Oscillator potential in the z direction with spring constant γ . Write
down the expression for all the energy levels and the ground state wave function (lowest
energy eigenstate).
2 marks
2) Demonstrate the commutation relation [ xˆ , pˆ ] = ih in the position and in the momentum
representation by applying it to the appropriate wavefunction. Write down the one
dimensional Schrödinger equation in both representations when the potential is given by
V ( x ) = kx .
2 marks
3) Consider a particle of mass m in a simple harmonic oscillator potential with spring
constant γ . Find the expectation values of the position and the momentum operators if
the system is in its lowest energy state.
2 marks
4) How does quantum mechanics predict the measurement outcome of an experiment?
Demonstrate that by taking as an observable the momentum operator p̂ when the
particle is at an eigenstate of the momentum.
2 marks
p2 h2 d 2
5) Show that the kinetic energy operator =− is a Hermitian operator for a
2m 2m dx 2
particle confined in a box.
2 marks