which doesn't mean you lack information about the state of the particle.
Yes it does. Quantum observations (sometimes called "collapse of the wave function") are not time symmetric. Once you've experienced one you can't derive where you were before it. Otherwise you wouldn't be using the word "probability".
This inability to recover a previous state is, by definition, the loss of information.
Yes it does. Quantum observations (sometimes called "collapse of the wave function") are not time symmetric. Once you've experienced one you can't derive where you were before it. Otherwise you wouldn't be using the word "probability".
This inability to recover a previous state is, by definition, the loss of information.