[ExI] D-Wave's Quantum Computer

[Tomaz Kristan]

Don't ask me about MWI. I think it's just a religion like Global Warming.
Not be cause it is too weird, be cause it is too ilogical.

But since you've asked.

The real question here is, do we have a quantum computer now? Even if we
have, it is nothing more than an analog computer of a sort. I've always
admired them.


On Thu, May 23, 2013 at 9:11 AM, Giulio Prisco <giulio at gmail.com> wrote:

> On Thu, May 23, 2013 at 8:17 AM, Anders Sandberg <anders at aleph.se> wrote:
> > On 2013-05-22 22:22, Kelly Anderson wrote:
>
> > As far as I understand, they can be general purpose. You just use gates
> that
> > implement universal reversible operations. I don't think they would be
> > amazingly effective, but they could do it.
> >
> > Incidentally, since we are talking quantum computation. I have been
> trying
> > to track down a proper source on minimum energy dissipation for it. As
> far
> > as I get it, by virtue of reversibility QCs can run with no dissipation -
> > they do not erase bits, so the Landauer limit doesn't apply. But error
> > correction will be necessary, and error correction schemes involve
> dirtying
> > ancilla bits - these bits will have to be erased, at a thermodynamic
> cost.
>
> Can't the extra bits be just stored?
>
> BTW what do you guys think of this?
> It seems sort of plausible that the universe may be optimally
> energy-efficient. So it should be a reversible computer. But
> apparently it isn't because information is irreversibly erased in
> wavefunction collapse. But if the information is just stored away
> instead of destroyed, the universe can still be a reversible computer.
> Assuming the MWI interpretation, the lost information is, indeed,
> still available. So the MWI follows from Landauer theorem with some
> plausible assumptions.
>
> I am sure somebody must have written about this in much more details.
>
> > Does anybody know a paper placing bounds on how many ancillas are
> necessary?
> > I know there are theorems stating that if the error probability per gate
> is
> > under a certain constant in-the-large fault-tolerant computation is
> > possible, but most of these constructions seem to have huge numbers of
> gates
> > (literally millions per bit). Does anybody know a paper that instead
> > minimizes the number of expected erasures?
> >
> > Oh, and while still quantum:
> >
> http://news.sciencemag.org/sciencenow/2013/05/physicists-create-quantum-link-b.html?ref=hp
> > Entanglement between particles separated in time. Unsurprising, yet
> totally
> > rad.
> >
> > --
> > Dr Anders Sandberg
> >
> > Future of Humanity Institute
> > Oxford Martin School
> > Oxford University
> >
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