2 ms·
>This is especially problematic because QM doesn't predict any particular decomposition of a quantum state into particular classical states. It does predict it
by GoblinSlayer 4y ago
>This is especially problematic because QM doesn't predict any particular decomposition of a quantum state into particular classical states.
It does predict it, this decomposition is called decoherence, where a classical state splits into a superposition of several different classical states.
- pdonis 4y ago> this decomposition is called decoherence, where a classical state splits into a superposition of several different classical states. No, that's not what decoherence is. Decoherence is the spread of entanglement over a very large number of untrackable degrees of freedom (usually referred to as the "environment"). This makes interference effects unobservable. But decoherence itself does not involve any "splitting"; the entanglement that decoherence spreads over a very large number of untrackable degrees of freedom has to already be there before decoherence can act on it.
- GoblinSlayer 4y agoAFAIK the largest molecule to show quantum behavior in experiments is somewhere at 100 atoms. I suppose that's all "environment" you need for a large number of degrees of freedom. And yes, spread of entanglement does mean splitting. Entangled state is not factorizable, because all states in it are split. This splitting is the result of splitting of the initial state.
- pdonis 4y ago> I suppose that's all "environment" you need for a large number of degrees of freedom. No. The 100 atoms is the largest molecule that we can do experiments on without having decoherence happen and ruining our attempts to observe interference. The number of degrees of freedom in the environment is many orders of magnitude larger, something like 10^30 or more for a typical experiment.