
Researchers Prove Quantum Computers Are More Powerful Than Classical Computers - Osiris30
https://motherboard.vice.com/amp/en_us/article/evw93z/researchers-finally-proved-quantum-computers-are-more-powerful-than-classical-computers?__twitter_impression=true
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camillomiller
In case anyone's wondering: this is not Quantum Supremacy, yet. Just
theoretical proof of a quantum advantage of quantum calculators over binary
computer for some specific subset of problems. Very interesting nonetheless.

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thechao
Damn. And I just spent 10 minutes trying to explain quantum supremacy to 6
year old.

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quickthrower2
It sounds like a cross between a Bond and Bourne movie.

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mrhappyunhappy
Coming to theater near you.

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omazurov
[https://arxiv.org/abs/1704.00690](https://arxiv.org/abs/1704.00690)

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utopcell
Is it the case that a logarithmic gap is shown for a specific problem ? Why is
this a big deal ? Doesn't Grover's algorithm already demonstrate a sqrt(n) gap
?

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chowells
Only if you assume that the classical counterparts of it are optimal. There's
no proof of that.

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21
For Groover algorithm, which is applied to the problem of search you can prove
that there is no classical algorithm faster than O(N) - looking at each item
in the worst case scenario.

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wolfgke
> For Groover algorithm, which is applied to the problem of search you can
> prove that there is no classical algorithm faster than O(N) - looking at
> each item in the worst case scenario.

Assuming that you cannot "look into the black box of the oracle" (i.e. we are
only allowed to use a given oracle to evaluate an item at an index).

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21
You still have the case of a list of perfect random numbers. There is nothing
in the box then.

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wolfgke
But perfect random numbers cannot be evaluated by an algorithm. Evaluating the
black box/oracle must be done in a run of Grovers's algorithm.

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kakaorka
I don't think there are many doubts that quantum computers are more powerful
than classical in specific areas, or am I wrong?

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wolfgke
If you believe in the Cellular Automaton Interpretation of Quantum Mechanics
by the Nobel laureate Gerard 't Hooft (which is somewhat controversial among
physicists), building a sufficiently large quantum computer will probably be
impossible. His book is available for free:

>
> [https://link.springer.com/book/10.1007%2F978-3-319-41285-6](https://link.springer.com/book/10.1007%2F978-3-319-41285-6)

Simply read section 5.8.

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krastanov
While t Hooft is a genius, this particular work of his is not taken very
seriously by most researchers.

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wolfgke
> While t Hooft is a genius, this particular work of his is not taken very
> seriously by most researchers.

As I wrote: this work is controversial. For a very positive review, see for
example

>
> [https://physicstoday.scitation.org/doi/10.1063/PT.3.3629](https://physicstoday.scitation.org/doi/10.1063/PT.3.3629)

According to 't Hooft himself (source:
[https://physicstoday.scitation.org/do/10.1063/PT.6.4.2017071...](https://physicstoday.scitation.org/do/10.1063/PT.6.4.20170711a/full/))
"The response [by fellow researchers] has been very mixed. Many other
researchers are clearly very skeptical. They should be, because there are
important unanswered questions. Others have expressed their interest and
support. What concerns me is that I haven’t yet found colleagues who
completely understand my approach. And also, of course, I don’t know what they
say behind my back.".

~~~
akvadrako
Controversial is not the same as “not taken seriously”. It’s really fringe.

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adamnemecek
Everyone talks about qubit quantum computers but I'm really souped for
continuous variable quantum computers.
[https://en.wikipedia.org/wiki/Continuous-
variable_quantum_in...](https://en.wikipedia.org/wiki/Continuous-
variable_quantum_information)

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krastanov
This is more of a hardware implementation choice than anything else. On top of
such hardware we are still going to implement "digital" systems of qubits (or
qudits).

I work at the Yale Quantum Institute, and people here are some of the bigger
proponents of continuous variable quantum hardware. It is a fascinating design
choice, but the final goal is the same: make something error corrected and
qubit-like.

The reason for this is that you need to switch to digital if you want to be
able to scalably correct errors (there is no such thing as scalable analog
error correction).

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adamnemecek
I’m well aware. I just don’t think that we’ve given analog error correction
good enough of a shake.

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hexane360
Why don't we start with classical systems then?

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skeptic_69
I don't understand why you would publish this in nature instead of FOCs/STOC

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anon4738383
To be clear, Turing complete is Turing complete... quantum or classical, they
are both general purpose, eg, able to execute an instruction set operating on
fixed-sized integers. Certainly there will be improvements on classical code
using quantum algorithms, but those will be reasonably-simulatable on
classical computers... implying that quantum computers aren't necessarily
special in terms of functionality, only in potential runtime and, for now,
restriction to special-purpose acceleration of some classical operations.

Certainly, quantum computers will be advantaged in terms of theoretical and,
likely, practical runtime of algorithms and code compared to classical
computers.

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hadsed
Well i think that has a twinge of negativity to it. I think what people forget
is how important simulating quantum physical/chemical systems is. That's a
problem that is extremely intensive even with our large numbers of approximate
algorithms on supercomputers. At the moment you need almost a PhD in both high
performance computing and the science to get anywhere. But what if physicists
and engineers could simulate a complex quantum chemistry experiment in a
Mathematica notebook? I imagine it'll change industries (think about how many
engineers there are now that are effective with basic off the shelf AI tech
right now).

