
World's Largest Quantum Computation Uses 84 Qubits - llambda
http://www.technologyreview.com/blog/arxiv/27483/
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sbierwagen
Sure wish I could still flag submissions.

As maggit points out, (exactly as I did 228 days ago[1]) D-Wave has a long,
long history of writing press releases that sound very interesting; then
completely failing to follow them up.

An Arxiv preprint is a step up from a press release, but it's still not a
_peer reviewed paper._ I haven't read it, nor do I know enough number theory
to comment intelligently on its contents, but judging from D-Wave's past
history of behavior, this paper is almost certainly fraudulent.

Extraordinary claims require extraordinary evidence. This is not extraordinary
evidence.

1: <http://news.ycombinator.com/item?id=2593323>

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malvosenior
You can purchase a working D-Wave machine today. I'm not sure how that
qualifies as "failing to follow them up".

~~~
Dylan16807
Easy, I'll quote the end of the article.

 _The company's approach to computing, known as adiabatic quantum computing,
has been heavily criticised. Various physicists have said that the theory
behind the machine is flawed and that the company has shown little evidence of
the kind of improvement expected over classical computers._

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maggit
There seems to be some controversy as to whether or not the D-Wave machines
actually are quantum computers. I don't understand this fully myself (so
please elaborate if you can!), but it seems incredible that this 84 qubit
quantum computer would just pop out of nowhere when the state of the art seems
to be just a few qubits.

<http://en.wikipedia.org/wiki/D-Wave_Systems#Criticism>

~~~
waqf
My very limited understanding is that they have built a kind of analog
computer that solves minimization problems. They claim it's an "adiabatic
quantum computer" (a relatively-recently theorized implementation of quantum
computing) but the skeptics think that it works by some classical method such
as simulated annealing and therefore will never outperform classical
computers.

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hessenwolf
Can somebody elaborate? I am waiting for the day I get to wet myself with glee
and shamelessly create arbitrarily complex Bayesian statistical models and
brute force the parameter estimates with MCMC on a quantum PC... that will
change things.

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lifeisstillgood
A good friend of mine with a PhD in this stuff points out that to do any
useful work (ie breaking 3DES) you need a qubit for every bit in the
factor(key), and all must be super-positioned at the same time - and that
getting each extra bit superpositioned seems to be getting exponentially
harder - in short quantum computing is looking to be technically much much
harder than hoped. Kind of next century harder.

~~~
stcredzero
Yes, but I'd bet that lots of real world cryptosystems have bugs in them that
reduce their effective entropy to 84 bits or less.

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noodly
I would like it to be true, but apart from computing known values of Ramsey
numbers, they should have computed unknown values of Ramsey numbers, to make
their research more valuable.

As the bounds of small Ramsey numbers are known, it would provide more
evidence of correctness of their computation.

