> On 17 Oct 2018, at 00:33, Bruce Kellett <[email protected]> wrote: > > From: <[email protected] <mailto:[email protected]>> >> >> On Monday, October 15, 2018 at 3:28:17 PM UTC, [email protected] >> <mailto:[email protected]> wrote: >> >> On Monday, October 15, 2018 at 11:17:56 AM UTC, Bruce wrote: >> >> >> The state is still the original state until decoherence kicks in and then, >> because of einselection of a preferred basis, we can say that the separate >> states are "real" -- namely orthogonal, so that one other other is chosen. >> Until that time, the only state around is the original state, as can be >> demonstrated by the possibility of recoherence, in which case you recover >> just the initial state and nothing else. >> >> Aren't the component states orthogonal prior to decoherence? IIUC, they must >> be if they have distinct eigenvalues. AG >> >> I conclude that not every superposition has components that are eigenvectors >> of the operator for the observable. So these components are not orthogonal. >> But there is always an expansion whose components are eigenvectors and thus >> are orthogonal. I don't think this has anything to do with decoherence. AG > > My use of the word "orthogonal" was careless -- basis vectors can be > orthogonal or not, it makes no difference to the state or the fact of > superposition. What I meant about decoherence was that it renders the density > matrix diagonal (FAPP), so that the superposed states no longer interfere. > >> What continues to puzzle me is why the alleged experts here of quantum >> computing (and I think Wiki as well) claim that qbits are in both states >> simultaneously, when we know this is not a correct interpretation of a >> superposition. Does the theory of quantum computing depend in any way on >> what appears to be an erroneous interpretation of a superposition? TIA, AG > > I leave quantum computing experts to comment on this, but I tend to think > that such language is misleading at best.
I might develop this when I have more time, and it is anything but easy. Let me say that it is hard for me to conceive that the superposition are not all real “in some sense” to understand how the quantum Fourier transform work. It is hard for me to conceive a non “many-things” theory to remain a bit realist on physics, and to grasp how a (quantum) computer can physically factorise a big number n (in polynomial time P(n)). That might be as complex as showing that P = NP. Bruno > > Bruce > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > To post to this group, send email to [email protected] > <mailto:[email protected]>. > Visit this group at https://groups.google.com/group/everything-list > <https://groups.google.com/group/everything-list>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
