Recent comments from SciRate

This looks like a wonderful paper: the questions are simple to state and natural, and the direction looks new and exciting.
From what I recall, there has been some concern among people that QPCP conjecture is hard to prove (or may be even false), because we have not identified the correct analogue

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Aram an answer to your question (quantitative setting) can be found here
http://arxiv.org/abs/1309.1472

What journal is that (Quant. Inf. Rev.)? First volume, first number, first pages... Is it his own journal, freshly established?

The framework is quite restricted/restrictive (only two qubits, a particular encoding, disallowing everything but qubit measurements in the "classical" case) and that is probably the reason why everything fits so well together. But I believe the approach goes in one interesting direction: taking adv

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Thanks, I should have used quotation marks in my one lazy attempt at Google...

Although the editorial board looks very good, I am afraid the journal started with the wrong step.

I believe the results presented in this paper are very similar or very closely related to those given in the appendix/supplementary material of http://arxiv.org/abs/1203.1268 in particular Theorem 3

At a closer inspection, although some of the equations and the framework are very similar, what considered here and in http://arxiv.org/abs/1203.1268 is quite different. In http://arxiv.org/abs/1203.1268, no initial entanglement is supposed to exist, and the structure of the states is not as general

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This result already follows from results of Beigi and Shor http://arxiv.org/abs/0709.2090 (not cited in this paper) by employing the Koashi-Winter relation.

Very nice how the math in the abstract renders on Scirate! I wonder if the arXiv will catch up...

This paper was recently accepted into PRA. I was a referee for it and the comments in my final report were left as optional by the editors after it was discovered that I coauthored a paper on a similar topic. Since the final published version of the paper still contains some problems and the authors

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What is a bosonic bat?

It would be interesting to hear machine learners view of this paper. Any AI folks lurking around scirate care to comment?

This paper only considers two party entanglement. If you move to three parties, then the entangled states in the GK theorem include the GHZ state and the measurements that you need in order to violate Bell inequalities for these states. Thus the argument in this paper seems to fall apart for n>2 q

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After equation (17), I believe the author means to measure in the x-basis?

I somehow missed Eric's Ph.D. thesis. For those who are interested it is: http://arxiv.org/abs/quant-ph/0503169

This is a very useful exposition and classification of entanglement witnesses, which I expect will prove very useful for those of us working in the field.

I must note that for future work, you may be interested in considering nonlinear witnesses as well, as they provide a generalization of linea

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Please consider the environment before printing this full version. :)

Very impressive. I wonder if this method can be extended to electrons, to develop an entanglement-enhanced electron microscope?

GHZ state is separable if you trace out any subsystem. Therefore I don't think you can violate Bell inequality with GHZ state.

Hi John,

Your comment made me reread our abstract, which I now see to be potentially misleading. It will need to be clarified in a future version. Thanks for that! That said, I would summarize the main points of the article thusly:

1. Adiabatic quantum computers/annealers/optimizers are robu

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Nice! :)

Wow, 33 cites. Congratulations to Toby and Ashley. Very nice results. BTW, is this a record high on Scirate?

Yes. It looks the same to me, the "y" in line 2 of equation 17 appears to be in the x-basis, not the computational basis, and so should also be should measured in the x-basis. It can't possibly be a z-basis measurement because then we'd just get x or x+a. Must be a small typo.

Hi Steve:
Thanks for the comments! I was not aware that the GK theorem implies that the Schrödinger and Heisenberg pictures are not computationally equivalent. Otherwise it is not clear that we are trying to say anything really new here but rather, as you said, something elementary. We wanted to, i

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The last RMP is also here: http://arxiv.org/abs/0812.0380

About GK theorem and Heisenberg picture : as a physicist, I understood this theorem when I made the link with with the Heisenberg picture. Using the GK algorithm is tracking the value of operators over the evolution of the circuit, exactly like calculation in the Heisenberg picture. And they show th

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This paper restates the problem of finding MUB vectors in terms of density matrices rather than pure states (see Prop. 2). The vectors w in Prop. 1 are just the generalized Bloch vectors of the corresponding states. I don't think this brings any new insight or makes the problem any easier to solve.

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This publishing company has other journals on highly specialized topics besides quantum information. For example, "Bahrain Student Research Journal" and "The Arabian Journal of Accounting":
http://naturalspublishing.com/Journals.asp

I wonder if a Mathgen paper would get accepted here. Here is a

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Indeed, the link to the editorial board's page has been removed from the menu bar. However, the page itself is still available:
http://naturalspublishing.com/show.asp?JorID=16&pgid=73

If you dig more, it just gets more and more interesting. For example, they organize conferences too:
http://con

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This one is an interesting read...

It provides a novel way of measuring the impact factor and h-index as a percentage. In this way we can compare different journals and authors on an absolute scale! The only drawback is that the new method works only for Arabic journals.

Needless to say, the p

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The Desperado puzzle in Fig. 4.1 is pretty cool. They even give a link to a YouTube video on how to solve it!

Here are some related results:
http://www.win.tue.nl/~gwoegi/P-versus-NP.htm

I wrote an intuitive summary of what this paper does:
http://marozols.wordpress.com/2013/05/29/sic-povm-sickness/

A similar result has already been obtained by Marcus Appleby: see Sect. 4 of
http://arxiv.org/abs/quant-ph/0611260

:)

I like this paper, so I wrote a blog post about it:
http://marozols.wordpress.com/2013/07/07/exact-quantum-query-algorithms/

Thanks should go to Noon Silk, who sent a patch to add MathJax support.

@Noon Silk. I do not know what to say about heuristic 3, but, in relation to your first question, let's assume that all heuristics are valid and apply theorem 2 to solve the Discrete Logarithm over Z_q*, where q is prime. As far as I understood (someone please correct me if I am wrong) the algorithm

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"the entangled states in the GK theorem include the GHZ state and the measurements that you need in order to violate Bell inequalities for these states"

If this is true, the GHZ state and all local measurements' projectors needed for Bell inequality violation must be in the same MUB polytope, con

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Physicists may be also interested in a realistic proposal of DFS computation with solid-state qubits: Phys. Lett. A 374, 3285 (2010), arXiv:0903.1056 [quant-ph]

This is almost identical to my previous work:

http://arxiv.org/abs/0904.1969
http://arxiv.org/abs/0906.4133
http://arxiv.org/abs/0909.2432

This Harvard-MIT Lincoln Lab paper claims that quant-ph/0303039 by Bullock and Markov was the first paper to give an exact decomposition of diagonal unitary matrices into elementary gates. That’s false. This Bullock Markov paper repeats the exact decomposition of diagonal unitary gates which was qui

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The paper says
"To implement an n-qubit diagonal unitary exactly on a
quantum computer generally requires 2^{n+1} − 3 one- and
two-qubit gates [7]. However, one is usually interested
in circuits that approximate the unitary to within some
error tolerance, \epsilon." [7]=Bullock-Markov

NOW yo

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Hi Aram,
Could you please tell me, what is the most efficient way known to project out the totally symmetric part from an arbitrary n qudit pure state?

Sorry, I now realize it's a dumb question. No need to answer it.

Hi Courtney and Steve,

I wouldn't say that it is a linear Bravyi-Haah, but I can see the similarity. Bravyi-Haah clusters all neighbours within a length scale, as Steve says, whereas I just do a pairing. I think that will result in quite different behaviour. The nice crossover point for the thres

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Hey James,
It seems to me that this decoder is very similar to the Bravyi-Haah decoder but with a linear schedule of length scale increases instead of the exponential schedule as described by BH. Can I think of your decoder like this or is it an inaccurate comparison?

Thanks Oded, I will pass it on to my co-authors. The combination of the two results seems to give quite a strong argument that DQC1 is truly intermediate.

No.

I have not gone through all the details, but it seems that some of the results are already antecipated in the paper below, where they show
that states with discord created locally can not be used for entanglement distribution.

http://link.aps.org/doi/10.1103/PhysRevA.87.032340