Re:Physicists rewrite a quantum rule that clashes with our u...
by Maro on Tuesday September 27, 2022 @08:43AM
(#32994593)
Classically, isn't the reverse program just (?):
X = 5
X = 4
I feel like 2 things are being mixed. In QM/QC, the operators must be unitary, which roughly means they "rotate" states and their inverse "rotation" exists, so (in principle) the reverse operation can be performed; so (in principle), we can construct the reverse operations, execute them, and kinda reverse the time evolution. But it doesn't mean that the quantum state (at time t) of the system encodes the time history (t'<t) of the state.
Re:Physicists rewrite a quantum rule that clashes with our u...
by whimsicalism on Tuesday September 27, 2022 @12:13PM
(#32997332)
> But it doesn't mean that the quantum state (at time t) of the system encodes the time history (t'<t) of the state.
it does if you take an everettian perspective on QM, the universal wavefunction at time T can always be unwound to time T'.
Re:Physicists rewrite a quantum rule that clashes with our u...
by currenciessfe on Tuesday September 27, 2022 @07:16PM
(#33002377)
I should have been more specific, the 4 and 5 values are dynamic runtime values, not constants known ahead of time.
In classical computers you can do:
In quantum computers this sequence of operations is impossible, because the program needs to respect unitarity and need to be able to be undone/run backwards.But you can't run this program backwards because the second operation (=5) completely erases the information from the first step (=4)