Quadratic-norm proof of the Heisenberg uncertainty relation (source code)

= Quadratic-norm proof of the Heisenberg uncertainty relation

For a state with zero position and momentum means, positivity of $\lVert(p-isx)\psi\rVert^2$ for every real $s$ gives
$$
(\Delta p)^2+s^2(\Delta x)^2-s\hbar\geq0.
$$
The discriminant is nonpositive, hence $\Delta x\,\Delta p\geq\hbar/2$.