
When can Quantum Annealing win? - runesoerensen
http://googleresearch.blogspot.com/2015/12/when-can-quantum-annealing-win.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+blogspot/gJZg+(Official+Google+Research+Blog)
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ivan_ah
> from the paper
> [http://arxiv.org/abs/1512.02206](http://arxiv.org/abs/1512.02206) : _we
> report the total computational effort of QMC in standard units of time per
> single core._

That's an interesting way to compare quantum and classical computer
"substrates" on the same footing: running time.

> _Based on the results presented here, one cannot claim a quantum speedup
> [...] as this would require that the quantum processor [to] outperform the
> best known classical algorithm. This is not the case... because a variety of
> heuristic classical algorithms can solve most instances of Chimera
> structured problems much faster than SA, QMC, and the D-Wave 2X_

So no quantum revolution yet, but potentially for larger problems and when the
quantum "substrate" becomes more expressive, we'll see classical heuristics
fail and quantum annealing win.

~~~
nickpsecurity
I'll add that I could cram a bunch of ASIC's with accelerators for annealing
problems in a machine the size of D-Wave. You'd see magnitude-higher speedup
without anything quantum at all. I'm not sure if they looked inside of one to
see exactly what's running in it but I'd rule out classical acceleration
methods first.

~~~
eveningcoffee
I base my speculation on this comparison:
[http://bitcoin.stackexchange.com/questions/36412/what-is-
the...](http://bitcoin.stackexchange.com/questions/36412/what-is-the-
difference-in-speed-between-a-gpu-and-an-asic-per-dollar-of-cost) between GPU
and ASIC bitcoin mining and on [https://en.bitcoin.it/wiki/Non-
specialized_hardware_comparis...](https://en.bitcoin.it/wiki/Non-
specialized_hardware_comparison) for GPU and CPU comparison.

From this the difference between between GPU and ASIC solution is about 10^4.

Google tested against Intel(R) Xeon(R) CPU E5-1650 single core, so it would be
roughly 10^3 slower than GPU.

So one could say that ASIC solution for bitcoin mining is about 10^7 times
faster than single core CPU solution.

So in this sense parents claim checks out.

Now I do not know if it is possible to generalize these finding to the problem
in question.

~~~
eveningcoffee
It looks like the actual difference is 10^6.

------
mikeyouse
Since I didn't know the naming scheme for D-Wave products, they are testing
the "D-Wave 2x" which is the latest generation, 1,000 qubit quantum annealer,
from the press release when it was launched (Which I just noticed was also
linked in the Google post..):

    
    
        In addition to scaling beyond 1000 qubits, the new
        system incorporates other major technological and
        scientific advancements. These include an
        operating temperature below 15 millikelvin, near
        absolute zero and 180 times colder than interstellar
        space. With over 128,000 Josephson tunnel
        junctions, the new processors are believed to be
        the most complex superconductor integrated circuits
        ever successfully used in production systems.
        Increased control circuitry precision and a 50% 
        reduction in noise also contribute to faster
        performance and enhanced reliability. 
    

[http://www.dwavesys.com/blog/2015/08/announcing-d-
wave-2x-qu...](http://www.dwavesys.com/blog/2015/08/announcing-d-
wave-2x-quantum-computer)

------
koobz
Curious what effect a doubling in the DWave machine's "qubits" would have on
this factor and how soon that's likely to be achieved. Does the complexity /
cost of building such a machine scale linearly with the number of qubits
involved?

Are there problems that are reducible to quantum annealing that become
attractive with such a performance improvement?

------
eveningcoffee
I guess it is good time to recall this news:
[http://phys.org/news/2014-11-largest-factored-quantum-
device...](http://phys.org/news/2014-11-largest-factored-quantum-device.html)

