

D-Wave Defies World of Critics With ‘First Quantum Cloud’ - raghavsethi
http://www.wired.com/wiredenterprise/2012/02/dwave-quantum-cloud/all/1

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julian37
_The classic example is figuring out the most efficient route for a traveling
salesman going to multiple destinations. [...] For example, if you have six
destinations, there are 64 possible combinations. If you have 20 destinations,
there are 1,048,576 possible combinations._

That's incorrect, the number of combinations for N destinations is N!, not
2^N. So for 6 destinations there are 720 combinations and for 20 there are
2.43290201 × 10^18.

[http://en.wikipedia.org/wiki/Permutation#Counting_sequences_...](http://en.wikipedia.org/wiki/Permutation#Counting_sequences_without_repetition)

~~~
dljsjr
Only using naive algorithms. You can get it down to 2^n time complexity by
increasing the space complexity and applying dynamic programming techniques.

[https://en.wikipedia.org/wiki/Travelling_salesman_problem#Ex...](https://en.wikipedia.org/wiki/Travelling_salesman_problem#Exact_algorithms)

~~~
julian37
Just like the article I didn't say anything about space or time complexity,
only about the number of combinations (permutations) of visiting N
destinations. That number is constant regardless of how sophisticated your
algorithm is :-)

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dustingetz
> That same month, mega defense contractor Lockheed Martin bought a D-Wave
> quantum computer and a support contract for $10 million.

lol, i used to work at LM advanced research, LM consistently blows 10 mil over
3 ears on stupid dead end projects and nobody even blinks. This is not a
criticism of LM so much as it gives us insight into the size of budget and
scope of projects the work with. they did 45bn revenue in 2011 per wikipedia.
this d-wave project looks like a toy that some kids in a lab bought.

but it doesn't matter how it looks to us. quantum computing is a weapon, and
as such is highly classified. i'm not sure we can draw any conclusions at all
about the state of quantum computing from information in the public domain and
if LM had a larger relationship with d-wave or similar companies, we wouldn't
know.

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loboman
Are you saying that Lockheed had 45bn revenue in 2011 from wikipedia? how does
that work?

~~~
aaronblohowiak
The parent is citing wikipedia. Saying "per wikipedia" is using "per" to mean
"according to", not using it to mean "for each"

<http://en.wikipedia.org/wiki/Lockheed_martin>

~~~
loboman
Thank you for the clarification. I didn't know that.

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algolicious
Scott Aaronson recently wrote an informative article about his trip to D-Wave:
<http://www.scottaaronson.com/blog/?p=954>

Most interesting to me: "Geordie presented graphs that showed D-Wave’s quantum
annealer solving its Ising spin problem “faster” than classical simulated
annealing and tabu search (where “faster” means ignoring the time for cooling
the annealer down, which seemed fair to me). Unfortunately, the data didn’t go
up to large input sizes, while the data that did go up to large input sizes
only compared against complete classical algorithms rather than heuristic
ones. (Of course, all this is leaving aside the large blowups that would
likely be incurred in practice, from reducing practical optimization problems
to D-Wave’s fixed Ising spin problem.) In summary, while the observed speedup
is certainly interesting, it remains unclear exactly what to make of it, and
especially, whether or not quantum coherence is playing a role."

~~~
ihnorton
for folks in the Boston area, this meetup might be of interest:
[http://www.meetup.com/Theoretical-Computer-Science-
Problem-S...](http://www.meetup.com/Theoretical-Computer-Science-Problem-
Solving/events/51447842/)

~~~
davorak
I went, he is an enthusiastic speaker defiantly worth attending.

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adrianN
This article is full of bullshit claims about the power of quantum computers.
There are no known quantum algorithms for NP-complete problems like the
travelling salesman problem mentioned in the article that run faster than
exponential time. Quantum computers in general don't consider an exponential
number of possible solutions, or if they do, you can't extract the true
solution from the quantum state.

~~~
Tossrock
There seems to be a general misunderstanding of what quantum computers are
capable of in the public mind, or at least that slice of it that is even aware
of quantum computers' existence. I was just reading Hominids by Robert J
Sawyer and it involves a quantum computer. He describes how it 'checks every
possible answer simultaneously' to find the prime factors of a number
instantaneously...which of course is not how Shor's algorithm actually works.

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sharkbot
In a nice instance of synchronicity, I was just reading a paper by Scott
Aaronson, "NP-Complete Problems and Physical Reality" [1]. The paper talks a
little bit about the quantum adiabatic method, which seems to be similar to
simulated annealing, with similar limitations (on specially chosen SAT
problems, the method can have difficulty overcoming local optima; see page 6
for discussion).

So, D-Wave may be selling an expensive simulated annealing hardware
implementation, rather than a quantum computer.

1: <http://www.scottaaronson.com/papers/npcomplete.pdf>

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brimpa
It seems that every time I read articles about quantum computing, the increase
in computing power is described with gaping hole:

1\. Qubits can be 1 and 0 at the same time

2\. ...

3\. Solve hard problems!

Can someone provide a link that fills in the middle somewhat? Preferably,
aimed at an audience with something closer to undergrad engineering degree and
than a PhD?

~~~
smallblacksun
[http://michaelnielsen.org/blog/quantum-computing-for-the-
det...](http://michaelnielsen.org/blog/quantum-computing-for-the-determined/)

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davorak
> On some level, Rose understands the criticism. “It’s the same basic human
> reaction that everybody has to something that someone says that sounds
> outrageous,”

I think it less about it being outrageous and more about the fact that he and
the company's press releases sound more like infomercials then technological
descriptions. Which historically seems to happen with pseudoscience based
companies.

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pcvarmint
_"The great mathematician and founding figure of computer science, Alan
Turing, showed that it is impossible to eliminate all errors from software."_

Oh? I thought he only proved that it's impossible for an algorithm to
determine whether an arbitrary program will halt -- not whether all errors can
be eliminated from software.

~~~
lubutu
Indeed, it was the Curry–Howard correspondence which led to the realisation
that software could be proven correct: a function's type can be seen as a
proposition, the function itself a proof of that proposition.

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jgw
Quantum computing is here!

No, wait, it's over there!

One thing is for sure - we're uncertain where quantum computing is right now.

(yes, bad joke. It seems to work on a couple of different levels, though)

~~~
TeMPOraL
But for sure it's moving very fast!

(even worse follow-up on a bad quantum joke)

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lucaspiller
PDF for the Google paper mentioned in the article:
<http://arxiv.org/pdf/0912.0779v1.pdf>

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swordswinger12
To add to the myriad criticisms, I would only point out that quantum
computation was first proposed in 1982 by the late great Richard Feynman, not
by Deutsch.

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Devilboy
This is a terrible article, which is to be expected from Wired I guess.

