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One problem is the preferred basis. Why decoherence selects a particular basis? Another is that decoherence still does not explain the origin of probabilities.
by _0w8t 4y ago
One problem is the preferred basis. Why decoherence selects a particular basis?
Another is that decoherence still does not explain the origin of probabilities. I.e. there are models that shows how a pure classical system may arise. But we still have no explanation how a classical device interacting with a quantum system gets the value it measures.
- consilient 4y agoThe preferred basis is (roughly) the eigenbasis for the interaction term between the thermal environment responsible for decoherence and the decohering system in question, since those are the states that are robust to thermal noise. Outside the perturbative regime, there isn't a preferred basis because there aren't any classical observers.
- superposeur 4y agoTo add to this, the states robust to entanglement with environment were dubbed “pointer states” by Zurek since they are the quantum states most closely analogous to the “pointer” of a measuring apparatus showing one particular result.
- pdonis 4y ago> Why decoherence selects a particular basis? consilient answered this one. > decoherence still does not explain the origin of probabilities The amplitudes corresponding to each decoherent branch are the right ones to give the Born rule probabilities. Which, given that the Born rule is empirically observed to work, is probably as good as we're going to get unless (as I doubt will ever happen) someone manages to find a way to derive the Born rule from unitary dynamics.