

The Golden Age Of Quantum Computing, Once We Solve These Tiny Problems - jonbaer
http://www.fastcompany.com/3045708/big-tiny-problems-for-quantum-computing

======
semi-extrinsic
From the article: "How molecules interact at the quantum level, for example,
is difficult to study in a laboratory and impossible to simulate on a
classical computer."

Sorry, but that's just flat-out wrong, and this fact is a quick google search
away:

"Density functional theory (DFT) is a computational quantum mechanical
modelling method used in physics, chemistry and materials science to
investigate the electronic structure (principally the ground state) of many-
body systems, in particular atoms, molecules, and the condensed phases."[1]

[1]
[http://en.m.wikipedia.org/wiki/Density_functional_theory](http://en.m.wikipedia.org/wiki/Density_functional_theory)

~~~
hyperbovine
Next sentence:

"With this theory, the properties of a many-electron system can be determined
by using functionals, i.e. functions of another function, which in this case
is the spatially dependent electron density."

The object of study in DFT is the distribution of particles in the system
rather than the particles themselves. Which is all well and good, but the
article is technically correct in that exactly simulating n-body systems is
currently out of reach (in all problem domains) if n is huge.

~~~
semi-extrinsic
Sure, there's a limit to how large you can go, but people have recently been
doing DFT e.g. for the interaction between DNA bases and graphene sheets,
which is quite respectable. Quantum computing may offer better scaling at
large n, but since quantum computing is still largely unproven in practice,
and in particular since quantum hardware gets much harder to design and
implement as you increase the system size, it's quite probable that classical
computing will remain faster for the next 50 or 100 years.

You can compare it with matrix multiplication: we know of several algorithms
that are better than the naïve O(n^3), but they're essentially never used in
practice.

~~~
kolinko
Correct me if I'm wrong, but interaction with graphene sheets might me
relatively simple due to a simple structure of those.

Once we begin to deal with anything more complicated (e.g. two enzymes,
protein folding, etc) we very quickly reach a boundary of what traditional
computers can do.

~~~
semi-extrinsic
Well, you have to keep your tounge straight here. We're a very very far way
from doing DFT of protein folding, that's correct. But we have little reason
to believe that DFT is useful for studying the interactions of macromolecules;
these interactions are dominated by typical van der Waals forces, along with
repulsion and electrostatics, and this doesn't need a quantum mechanical
treatment. Then you're in the world of molecular dynamics etc., where we have
no problems simulating two enzymes interacting. See this paper where they did
fully atomistic simulations of an entire HIV capsule back in 2013:
[http://www.nature.com/nature/journal/v497/n7451/full/nature1...](http://www.nature.com/nature/journal/v497/n7451/full/nature12162.html)

------
mixedmath
Also from the article: "A quantum computer could also crack the most
sophisticated encryption in use today."

I think this gives the impression that all encryption methods known today fail
in the face of a quantum computer. But this is not true. There are a wide
array of "post-quantum cryptography algorithms" [1], or encryption schemes
thought to be secure against quantum attacks.

I suppose the author might have a particular scheme in mind which he considers
the "most sophisticated."

[1]: [http://en.wikipedia.org/wiki/Post-
quantum_cryptography](http://en.wikipedia.org/wiki/Post-quantum_cryptography)

~~~
kolinko
To elaborate on this. There's a whole group of quantum-safe algorithms, like
SHA-2 (used in Bitcoin among other things).

The best quantum computers can achieve is 2x increase in speed.

------
appden
This was a really good science piece by Fast Company. I do wonder how "factors
of a prime number" gets by editorial. You don't need a quantum computer to
tell you those. :)

------
SoftwareMaven
_Mark Ritter, who oversees scientists and engineers at IBM’s T.J. Watson
Research Laboratory, wrote: "I believe we’re entering what will come to be
seen as the golden age of quantum computing research."_

Golden age of quantum computing _research_. That's a very different thing from
a golden age of quantum computing.

