
HPE's New Chip Marks a Milestone in Optical Computing - jonbaer
http://spectrum.ieee.org/semiconductors/processors/hpes-new-chip-marks-a-milestone-in-optical-computing
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jpmattia
One of their papers (pdf):
[https://icrc2016.exordo.com/files/papers/45/final_draft/ID04...](https://icrc2016.exordo.com/files/papers/45/final_draft/ID045_ICRC2016_finalpaper.pdf)

Not exclusively silicon-based work, btw.

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dekhn
The underlying technology is awesome and neat but I can't see this exceeding
whatever required threshold to be useful, compared to modern computers. That's
simply because modern computers based on ICs have 40+ years of R&D behind them
to make them do what programmers want, really fast.

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forgotpwagain
An advantage of the silicon photonics (over other on-chip optical
technologies) is that we can leverage a lot of the experience that we have
with silicon to fabricate these devices. There are still large technological
challenges, since we often need to introduce new types of materials, etc, but
we're not _totally_ out of luck -- there's useful knowledge that can be
carried over.

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dekhn
it's pretty clear what's being built here is outside of what typical fabs can
build. You need a research fab with top of line equipment. The article
basically says they _had_ to do chip-style architecture to get the optical
paths to be stable enough to do reliable computing.

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SolarNet
Talk about scientific illiteracy in science media.

> “traveling salesman problem”

They quoted it - which means they obviously don't know what they are talking
about - and then go on to talk about esoteric things (Ising machine) as if
that's some sort of justification.

An Ising machine is also a Turing machine and the traveling salesman problem
is NP complete. Which means no breakthroughs. It can however, maybe, be more
performant at certain kind of problems (like statistical solutions to
optimization problems... like the traveling salesman problem). Like a GPU is
more performant at doing lots of floating point operations at once; but not
that it will be any faster, in the large scale, at solving _hard_ problems
like the traveling salesman problem.

And they present it with a vague description which makes it sound like it
might just be some sort of quantum system. It isn't. The failure to provide
facts, to challenge assertions and claims, to actually know, in our news media
is super annoying.

And the clickbait, uggh.

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dvdkhlng
Sorry to be nit-picking, but:

* the travelling salesman problem is NP hard, not NP complete (i.e. verification of the optimal solution is not in P).

* An Ising machine is not a turing machine, AFAIU, and it may not be turing complete (but not sure about that). AFAICS that machine merely implements search for an approximate optimum on some quadratic function of discretely valued variables. Maybe similar or even equivalent to the closest lattice point problem ([https://en.wikipedia.org/wiki/Lattice_problem#Closest_vector...](https://en.wikipedia.org/wiki/Lattice_problem#Closest_vector_problem_.28CVP.29)).

One could optimistically say, that this is a very special purpose machine.
Pessimistically I would say this is the only remotely usable "computation"
that can be implemented when you only have unreliable (non-deterministic)
components. So the fact that they did not implement a proper turing-complete
circuit may be more a bug than a feauture.

[edit] one may view their chip as a very fast hardware-accelerated
implementation of a very simple (i.e. slow) algorithm.

[edit2] Obviously, if the Ising machine is capable to find an exact solution
to an arbitrary NP-hard optimization problem, then that machine must be turing
complete (but still may take exponential time even for problems in P).
However, with an imperfect Ising machine (that does not implement perfect
annealing or retains an error rate even at lowest temperature) it is pretty
difficult to assess turing completeness.

