
Quantum computer calculates exact energy of molecular hydrogen - acangiano
http://www.eurekalert.org/pub_releases/2010-01/hu-qcc010810.php
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rw
_When a quantum computer is put to work on a problem, it considers all
possible answers by simultaneously arranging its qubits into every combination
of "zeroes" and "ones."_

This has _got_ to stop.

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joe_the_user
What do you mean?

Quantum mechanics is indeed a different viewpoint

As I recall, the Feynman diagram approach assumes that every conceivable
interaction between particles that could happen does happen with a given
probability depending on the interaction's complexity.

Indeed, the Heisenberg Uncertainty Principle is quite a mind fuck - if you
know the exact speed of a particle, the location of particle become _utterly_
uncertain to the point that it could be anywhere in the _universe_.

So what _specifically_ is your problem with the above quote?

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rw
Your comment is painfully embarrassing to read. Instead of attacking what I
said (or me), try asking: "could you elaborate on what you think the article
is misrepresenting?".

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RK
This is an example of quantum simulation, which is considered significantly
easier to achieve than general quantum computing.

Several quantum systems can be modeled with other, unrelated quantum systems,
to solve the dynamics of those systems. The cannot unfortunately be used for
general quantum gate operations that you hear about.

And as usual, for QC stuff, I'll defer any real comments to Michael Nielsen,
if he happens to see this submission.

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acangiano
This is arguably one of the most important breakthroughs ever in the field of
computing.

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joe_the_user
If it scale and lives up to the general description it will be. Whether it
will do that it another question.

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rms
[http://www.nature.com/nchem/journal/vaop/ncurrent/abs/nchem....](http://www.nature.com/nchem/journal/vaop/ncurrent/abs/nchem.483.html)

~~~
polynomial
How can I read the full article?

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mmastrac
After reading the paper here: <http://arxiv.org/pdf/0905.0887>, I think that
this wasn't actually done on a quantum computer, but rather simulated via
PyQuante: <http://pyquante.sourceforge.net/#>

It's still impressive, but goes to show that we're a long way from practical
quantum computing.

~~~
jackfoxy
I don't have the time right now to slog through what is probably a very
interesting paper, but this did catch my eye "We perform a key algorithmic
step the iterative phase estimation algorithm in full, achieving a high level
of precision and robustness to error. We implement other algorithmic steps
with assistance from a classical computer and explain how this non-scalable
approach could be avoided."

It sounds like they claim at least part of it they did with real quantum
computing. Scanning the paper I think they did some calculations on "real" one
and two qubit systems.

~~~
mmastrac
Ah yeah, I'm pretty sure you are correct after re-reading that part.

