Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

D-Wave: Truth finally starts to emerge

scottaaronson.com

Post reply on HN
Print view View original

21–30 of 97 posts

Re: D-Wave: Truth finally starts to emerge

#21

Post by kstop »

JanezStupar wrote: post #3
gadetron wrote: post #2

Holy Quantum Annealing Qubits Batman! That article was not for the faint of geek.

I understand some of the words, but the article itself seems to me as ancient Greek. Can someone explain to me what the hell the whole story is about?

A company that claimed to have built a general-purpose quantum computer, which would speed up a lot of computationally-intensive tasks, may have actually built a weaker device that does something called quantum annealing, which allows it to solve only a subset of problems - those that involve finding the lowest value state in a field of lots of values.

Furthermore, it doesn't look like the device solves those problems any faster than well-optimized code running on normal computers. Which cost about 10k times less.

Re: D-Wave: Truth finally starts to emerge

#22

Post by shawabawa3 »

nraynaud wrote: post #9

Is there a SDK? I'd like to port a NES simulator. (there is a conjecture that anything remotely able to do an addition will be used for emulating a Nintendo console)

I can try to give it a shot, however, I'm no expert and everything I write may be completely wrong.

Quantum annealing is essentially a quantum algorithm for searching in O(n^0.5) (as opposed to classical computing's O(n) )

D-Wave is attempting to build hardware that can perform quantum annealing

The news is that D-wave managed to perform quantum annealing

The author is sceptical that this is as impressive as it sounds because there is no evidence D-Wave actually did quantum annealing with a O(n^0.5) algorithm, and in fact it appears that it was in fact slower than simulated quantum annealing (that is, a classical machine attempting the quantum algorithm, which of course can be no faster than O(n))

Re: D-Wave: Truth finally starts to emerge

#23

Post by amalcon »

Zarathust wrote: post #7

Can anyone attempt to explain this in layman terms? I can't even figure out if this is a real paper or not!

I'm not an expert on quantum computing, but it looks like two points to me:

1) D-Wave devices have finally been proven to meet a fundamental requirement to do quantum computing. This is a significant scientific advancement.

2) Despite this, they don't seem to answer any computational questions more quickly than commodity electronic computers.

Again, I'm not an expert. The author's reasoning does seem sound. Still, I'm not qualified to assess either of those claims directly.

Re: D-Wave: Truth finally starts to emerge

#24

Post by sbierwagen »

varelse wrote: post #17

A really long time ago when I was in grad school playing with genetic algorithms and simulated annealing, I implemented something that seems awfully similar to quantum adiabatic annealing. It worked as follows: 1. Assign all states of each variable equal probability. 2. Sample the living crap out of the search space with some sort of energy function for every possible configuration, scoring the discrete values of the…

http://en.wikipedia.org/wiki/Quantum_Monte_Carlo ?

Re: D-Wave: Truth finally starts to emerge

#25

Post by danbruc »

sbierwagen wrote: post #14
JanezStupar wrote: post #3

Earlier quoted context omitted.

I understand some of the words, but the article itself seems to me as ancient Greek. Can someone explain to me what the hell the whole story is about?

QC is hard because it requires that the qbits be entangled with each other, but not interacting at all with the rest of the universe. This is comparable to trying to eat rice without a fork, or chopsticks, or allowing air to touch the rice. QC is very, very hard. It is entirely possible we won't see useful QC machines for decades, or even centuries. D-Wave has attracted scepticism because in the many press releases t…

Quantum annealing can be used to factor integers [1] (if those guys are correct) but the current D-Wave machines are probably unable to factor any interesting number. Here are some more hints [2] what is possible or not.

[1] http://physics.stackexchange.com/questions/11063/can-quantum...

[2] http://physics.stackexchange.com/questions/10496/what-can-th...

Re: D-Wave: Truth finally starts to emerge

#26

Post by bnegreve »

For the ones that don't want to read the whole post, the Truth is that the 3600 speedup claimed in this article: Commercial quantum computer leaves PC in the dust [1](HN discussion: [2]) isn't worth much.

Quoting Scott Aaronson's post: As I said above, at the time McGeoch and Wang’s paper was released to the media [...] the “highly tuned implementation” of simulated annealing that they ask for had already been written and tested, and the result was that it outperformed the D-Wave machine on all instance sizes tested. In other words, their comparison to CPLEX had already been superseded by a much more informative comparison—one that gave the “opposite” result—before it ever became public. For obvious reasons, most press reports have simply ignored this fact.

[1] http://www.newscientist.com/article/dn23519-commercial-quant...

[2] https://news.ycombinator.com/item?id=5697619

Re: D-Wave: Truth finally starts to emerge

#27

Post by kruhft »

I like that he addresses that his main fear that, if D-Wave does not succeed after riding the marketing hype-machine, a "QC Winter" would likely happen, not unlike the "AI Winter" (http://en.wikipedia.org/wiki/AI_winter) that occurred in the late 80's. The AI Winter was caused by a huge amount of over hyped claims and promises by the companies taking part which were never (and could never be) met, leading to the eventual collapse of the whole industry which is now only starting to see a practical recovery with the resurgence of Machine Learning.

D-Wave might be the belle of the ball today, but once the crowd turns, it could ruin an entire industry for a very long time. That's why skepticism is important when it comes to their claims.

Re: D-Wave: Truth finally starts to emerge

#28

Post by amalcon »

mikecane wrote: post #20

OK, so the problem D-Wave has itself defined can be run faster on classical machinery. Does this also hold true for other problems run on the D-Wave?

The way one solves other problems on the D-Wave is by reducing them to the D-Wave problem, so save in extraordinary circumstances the answer will be "Yes."

Re: D-Wave: Truth finally starts to emerge

#30

Post by prawks »

sbierwagen wrote: post #24
varelse wrote: post #17

A really long time ago when I was in grad school playing with genetic algorithms and simulated annealing, I implemented something that seems awfully similar to quantum adiabatic annealing. It worked as follows: 1. Assign all states of each variable equal probability. 2. Sample the living crap out of the search space with some sort of energy function for every possible configuration, scoring the discrete values of the…

http://en.wikipedia.org/wiki/Quantum_Monte_Carlo ?

Sounds an awful lot like Monte Carlo to me as well.
Post reply on HN