Animation of a wave packet tunneling through a barrier

This animation shows the probability density |psi|2 of a wave packet as it tunnels through a barrier at x=0. The width of the barrier is very small on the scale shown.


(1) Part of the wave packet is transmitted through the barrier and part is reflected from the barrier.

(2) Oscillations in |psi|2 are caused by interference between the incident and reflected wave packets.

(3) The wave packets become wider with time. This is due to the uncertainty in momentum which leads to increasingly uncertainty in position.