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Commercial quantum computer leaves PC in the dust

newscientist.com

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Re: Commercial quantum computer leaves PC in the dust

#41

Post by ryan-c »

jwr wrote: post #40
pja wrote: post #16

Earlier quoted context omitted.

Pretty much: Quantum Computers (QCs) can factor numbers (Shor's algorithm) and calculate discrete logarithms in polynomial time. I don't know whether there's an algorithm for hash-calculation that will let someone dominate the BitCoin hashing chain with a QC though. On the other hand, no one actually knows whether it's possible to build a quantum computer with enough q-bits that will stay coherent for long enough to…

What about elliptic curves-based asymmetric cryptography?

Elliptic curve cryptography can also be broken with Shor's algorithm.

Re: Commercial quantum computer leaves PC in the dust

#42

Post by mtrimpe »

mtrimpe wrote: post #9
igul222 wrote: post #5

Earlier quoted context omitted.

Not exactly. D-Wave quantum computers (like the one in the article) use "adiabatic quantum computing", which is more limited than normal quantum computing (it can't run every quantum algorithm). We're still a little ways off from breaking RSA.

Indeed; you can't build a quantum CPU with D-Wave's system. It's conceptually more similar to a GPU which can solve a specific subset of (non-embarrassingly-parallel) problems in polynomial rather than exponential time, with the published number of qubits essentially being the amount of working memory available. In practice these machines would probably be found optimizing certain steps in machine learning algorithms…

edit: Just to be clear, it does seem that adiabatic quantum computing can do factorization in quadratic time [1]

http://arxiv.org/abs/0808.1935

Re: Commercial quantum computer leaves PC in the dust

#44

Post by NamTaf »

I wrote a bunch of words about this [1] when it surfaced 4 days ago, but this NS article contains a bit more info. I'm really excited to see this presentation now.

Yes they've talked themselves up previously but if they're willing to front up with the evidence that they have something going on, I'm willing to give them the benefit of the doubt. After all, there's something to be said when the combined intellect of Google is willing to sink money in to your device.

[1]: https://news.ycombinator.com/item?id=5679278

Re: Commercial quantum computer leaves PC in the dust

#45

Post by easytiger »

Devilboy wrote: post #15
easytiger wrote: post #10

wouldn't it be more fair to compare to an FPGA solution for those problem sets?

Sure but that's not the point here. The important thing is that this quantum computer actually WORKS. In 2 years classical computers will be maybe 5 times faster. But this quantum computer will be 1000s of times faster (at these specific problems) so very soon any comparison will be irrelevant.

also i'm pretty sure if we used a computer of the same size as the quantum one (a fairly large room) it may also have been a different story)
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