I realise parents can be embarrased, in previouas generations superposition was done in private and entanglement was practically a taboo, the end result is people too embarrassed to talk about real problems, 58.567% of all left handed american men can’t sustain an entanglement long enough to satisfy their spouses. If you would still only emphasize: “but it is deterministic,” then, sorry, I would have nothing to add further w.r.t. this point.

I have not worked (or thought) through density matrices. I had gathered something about them when I read those topics in text-books, but being concerned more with the foundational issues, my reading was geared towards really understanding Schrodinger’s and Heisenberg’s “pictures” first, before anything else. (It precisely is the reason why I have kept studying relativistic QM in the waiting list for quite some time—even though it’s been years since I bought Dirac’s Principles book.) A pure state is not measurable, because the global phase cannot be measured, The global phase is absent for the description by the density matrix, and it turns out that the density matrix is indeed measurable (in a suitable sense). I think about the problem by taking a toy model of the universe like a cellular automata. It has a set of rules of physics that is classically deterministic. Now create a quantum version where initially all cells are in a superposition of their states. The universe is in a superposition of all possible states. That is the many worlds multiverse.In ppnl’s model, presumably, not just the updating rules but also the measurement rules which the observer cell uses in making its measurements, follow a classical, deterministic criterion. If the criterion is deterministic, it will impart a preferred basis. plan sequences of instructions to produce desired effects, test them out, decide how to change the instructions to improve their effect and then refine them as required and clearly describe the effect of their instruction sequences in a way that a non-expert can understand.

People who don’t know a lot but realize that QC is interesting but don’t oversell it. If they know enough they may thing that its likely SAT is not in BQP, though they may not know the terms.

Regardless of whether this tensor-network quantum state-space postulate is Platonically true, for a great many quantum engineering purposes it is effectively true, and this is is one strong motivation (among several) for the present-day flourishing of the literature on tensor-network state-spaces. People who don’t know a lot but think QC can do LOTS more than it can (or at least can now). The boy in your strip. People who do know a lot but think QC is not worth studying (Oded Goldreich might be in this category) Either this, or that, but not both. Equivalent to the XOR logic gate. Example: “Give me liberty, or give me death”