> On 14 Oct 2019, at 17:11, Alan Grayson <[email protected]> wrote: > > > > On Monday, October 14, 2019 at 3:40:01 AM UTC-6, Philip Thrift wrote: > > > On Sunday, October 13, 2019 at 11:10:58 PM UTC-5, Alan Grayson wrote: > > > On Sunday, October 13, 2019 at 5:50:35 PM UTC-6, Brent wrote: > > > On 10/13/2019 1:08 PM, Alan Grayson wrote: > > What are YOU talking about? I just made a GUESS about the decoherence > > time! Whatever it is, it doesn't change my conclusion. If there's a > > uncertainty in time, are you claiming the cat can be alive and dead > > during any duration? Is this what decoherence theory offers? AG > > Yes, part of the cat can be alive and part dead over a period seconds. > Or looked at another way, there is a transistion period in which the cat > is both alive and dead. > > But the main point is that this time had nothing to do with > Schroedinger's argument (he knew perfectly well the time of death was > vague); his argument was that Bohr's interpretation implied that the cat > was in a super-position of alive and dead from the time the box was > closed until someone looked in. > > Brent > > Agreed. Without decoherence, the cat would be in a superposition of > alive and dead from the time the box was closed until someone opened > it. With decoherence, it would be in that superposition for a very short > time, the decoherence time, when it would be in state, |decayed>|dead> > or |undecayed> |alive> before the box was opened, provided it was > opened after the decoherence time. So, as I see it, decoherence just > moves the "collapse" earlier, before the box is opened, and does not > resolve S's problem with superposition. The cause of the problem, or > paradox if you will, is the superposition interpretation of the radioactive > source. AG > > > > How would you describe the "states" of qubits in IBM's Q (quantum computer)? > > @philipthrift > > I am not familiar with the theory on which quantum computers are based, so I > cannot answer this question. AG
A quantum computer is just that, a computer that you can put in superposition state. You can put any bit in any arbitrary superposition state, like being 0 and 1 “simultaneously”. You can put the whole processor in a superposition state, even in the on/off superposition state. With a 64 quit computer, you can do 2^64 computations simultaneously, and then you can make a Fourier transform of all results, and get some information. Shor’s algorithm, to factorise large number, use such large superposition. David Deutsch invented it mainly to illustrate that we have to take the superposition state seriously, but of course e know this since at least Dirac. The technical difficulty is to get those stable, but progress have shown that it is possible, notably through quantum correction code (software solution) or through topological quantum computing (by squeezing electron in some way, we can build very stable superposition, unfortunately, the “squeezing apparatus” have to be huge, and this is not for tomorrow. But like Shannon theorem showed that we can transmit information on wires, the quantum correcting code technics refutes many impossibility statements once made in that field. That is why so many work on this. Bruno > > -- > 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 view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/589ff9a2-a63d-49c2-ac7b-291b2ba5bcd8%40googlegroups.com > > <https://groups.google.com/d/msgid/everything-list/589ff9a2-a63d-49c2-ac7b-291b2ba5bcd8%40googlegroups.com?utm_medium=email&utm_source=footer>. -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/8397FBDB-67D4-461A-B59C-7CED428D0E49%40ulb.ac.be.
