Recent content by JBlue

Thanks, vanhees71, for walking through the example. I had a silly confusion that is now perfectly cleared up!

HUP for spins reads $$\langle\sigma_z^2\rangle\langle\sigma_x^2\rangle \ge \frac{1}{4}|\langle\sigma_y\rangle|^2$$ Right after measuring ##\sigma_z##, we know it exactly, and so ##\langle\sigma_z^2\rangle=0##. However, HUP then implies that ##\langle\sigma_y^2\rangle=\infty## Even if we say...