3 ms·
Yes, this is true for any unitary operation on a different subsystem, and is known as the no-signalling principle. But this doesn't let you remove the second sy
by irljf 11y ago
Yes, this is true for any unitary operation on a different subsystem, and is known as the no-signalling principle. But this doesn't let you remove the second system: you are still stuck with a mixed state on the first system, not a pure state (in your case the state is 1/2 |0><0| + 1/2 |1><1|).
- infparadox 11y agoWell, I still don't see any thing wrong with the math. Even the authors rewrite the equations as sum(|A_k>|C_k>) instead of sum(|C_k>) and apply I(x)M_x instead of applying only M_x on |C_k> alone, this will not change the following equations.