b) If the wave packet width or variance in a) is initially squeezed, it will spread for a quarter of a cycle, then return to the squeezed value at the half-cycle, spread for another quarter of a cycle, and so on.
c) Squeezed vacuum state: the wave packet width or variance is oscillating in a simple harmonic oscillator potential well. The packet initially had a squeezed variance.
The paths traced by the oscillating packets as a function of time are also available as animations.
Expanded/Modified from: P. Meystre and M. Sargent III, Elements of Quantum Optics, Springer-Verlag, 1991.