I have an (undergraduate) degree in physics, or will at the end of the semester, and either I don’t fully understand the paper after a second read-through, or it is wrong. The claimed contradiction doesn’t seem to be particularly damning: if the measured state is excluded from being in a |0>|0> initial state, that doesn’t mean that the two cannot have started in a different state, and the excluded state will change in later measurements anyway, so the measurement is not telling you anything new.
(Motl’s explanation is harsh and caustic, but here I agree with him in interpreting the paper.)
Edit: I agree with Motl’s explanation of why the exclusion of 1 of the 4 combined states is not problematic.
Motl’s explanation is completely off-base because he’s trying to defend QM from attack when the paper is not trying to attack QM, but trying to distinguish QM from hidden-variables theories.
Of course P(i) = Tr( L | Z(i) >< Z(i) |) … that’s what QM says!
What they’ve just shown is that hidden variables theories that can’t do that, because the ‘real state’ L has specific values, and not a quantum nature.
I have an (undergraduate) degree in physics, or will at the end of the semester, and either I don’t fully understand the paper after a second read-through, or it is wrong. The claimed contradiction doesn’t seem to be particularly damning: if the measured state is excluded from being in a |0>|0> initial state, that doesn’t mean that the two cannot have started in a different state, and the excluded state will change in later measurements anyway, so the measurement is not telling you anything new.
(Motl’s explanation is harsh and caustic, but here I agree with him in interpreting the paper.)
Edit: I agree with Motl’s explanation of why the exclusion of 1 of the 4 combined states is not problematic.
Motl’s explanation is completely off-base because he’s trying to defend QM from attack when the paper is not trying to attack QM, but trying to distinguish QM from hidden-variables theories.
Of course P(i) = Tr( L | Z(i) >< Z(i) |) … that’s what QM says!
What they’ve just shown is that hidden variables theories that can’t do that, because the ‘real state’ L has specific values, and not a quantum nature.