Can you help me with this problem from Sakurai:
A particle of mass m in one dimension is bound to a fixed center by an attractive delta-function potential:
$$V(x) ~= ~-a\delta(x) , \qquad a>0.$$
At $t = 0$, the potential is suddenly switched off (that is, $V = 0$ for $t > 0$). Find the wave function for $t > 0$.