Recent comments from SciRate

Will Pol Apr 27 2021 02:45 UTC

Hey Ryan, thanks for the questions!

(1) Here we considered _all_ of the electrons, including core electrons. It's true that core electrons are not the primary factor in determining the chemical bondings, and thus including them to calculate ground state energies is neither necessary nor the most

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Māris Ozols Apr 24 2021 09:22 UTC

Thanks for your thoughtful comment, Dave. You're right, my one-liner was not particularly considerate and constructive. I did have my doubts about posting it and I'm still not sure how to properly react to this paper. But I also didn't want it to go unnoticed.

What triggered me is the wide gap be

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Noon van der Silk Apr 23 2021 07:18 UTC

Thanks for the message and setting the tone Dave. I completely agree with you and, speaking for the moderating team, we will aim to do a better job.

Dave Bacon Apr 22 2021 19:58 UTC

I've been thinking a lot about this comment (probably more than I should!) Certainly it's funny, "quant-hype" is a laugh out loud line. It reminds me of calling the US food retailer "Whole Foods" by the name "Whole Paycheck".

But I would also point out that if we want a community that is kind

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Ryan Babbush Apr 22 2021 02:42 UTC

This looks like a very thorough study with multiple substantial contributions, especially on the error-correction side. I have two questions:

(1) Are you simulating active spaces here, like other prior fault-tolerant studies using molecular orbitals, or are you including all the electrons (includ

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Thomas Vidick Apr 21 2021 18:07 UTC

I'm having trouble understanding the definitions of "reasonable" and "connected" given at the top of p.3 in this paper, maybe someone can help. The easiest, in order to clarify it, would be to say explicitly what is the graph $G_{supp(S)}$ for $S = Z_1$ and also for $S = Z_1 Z_2$ (in the example giv

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Māris Ozols Apr 19 2021 15:09 UTC

This should have been posted under [quant-hype].

Léo Colisson Apr 13 2021 10:47 UTC

Thanks to a careful reader (thanks to him!), we realized there were a typo in the affiliations: so no breaking news, Elham is not moving to Maryland ;-) I'm not sure how we missed that typo, but a v2 is waiting approval and should appear tomorrow to fix this.

Jens Eisert Apr 13 2021 06:47 UTC

Dear Ramis,

Thanks so much for your kind words. Thank you also for your insightful comments. Indeed, your beautiful work very nicely complements ours, in particular in the way you look at the asymptotic limits of large bond or physical dimensions. We have now discussed and cited your work in the

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Wojciech Kryszak Apr 12 2021 12:01 UTC

Hello,

I wish I could understand it more...
so I have a question about Fig. 3 (Fig. 2 in New J. Phys.-version) and all the argumentation from p. 4 hinged upon:

What if the proces depicted is not about some particle decay, but about some fully (FAPP) deterministic clock-gun mechanism that is s

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Blake Stacey Apr 06 2021 19:19 UTC

Thank you for clarifying! The history of this subject is complicated by independent rediscoveries, different terminologies being used by different fields, etc. We wrote [a review article](https://scirate.com/arxiv/1703.07901) four years ago that is already in some respects outdated!

Matteo Rossi Apr 06 2021 07:41 UTC

Dear Blake, thanks for pointing out that confusing statement in the appendix. In the statement, we were indeed referring to their choice of the tetrahedron. We will amend the sentence to reflect this, and also the fact that it was not introduced by them.

Blake Stacey Apr 03 2021 18:48 UTC

I'm a little confused by the statement in Appendix C that

> The second SIC-POVM used in this paper is the one introduced by Jiang et al.

From context, this doesn't appear to be referring to the specific method that [Jiang et al.](https://quantum-journal.org/papers/q-2020-06-04-276/) use (a Bel

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Alexey Uvarov Apr 02 2021 09:46 UTC

Probably a typo in the abstract: " In this paper, _we_ develop a method..."

Blake Stacey Mar 26 2021 03:55 UTC

Thanks for posting this! I was thinking along similar lines, though not nearly in organized enough a way to get anything written.

If I announced, "Instead of writing $a + bi$, now I will write ordered pairs $(a,b)$ that add entrywise and multiply like $(ac - bd, ad + bc)$," nobody would say that I

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Blake Stacey Mar 20 2021 18:43 UTC

I expanded on this comment in [arXiv:2103.09910](https://scirate.com/arxiv/2103.09910).

Aram Harrow Mar 20 2021 00:29 UTC

Does https://arxiv.org/abs/0912.4495 imply a very similar result?

Travis Scholten Mar 19 2021 13:15 UTC

For those interested, a related paper also hit the arXiv today on this topic: [_Experimental Characterization of Crosstalk Errors with Simultaneous Gate Set Tomography_](https://scirate.com/arxiv/2103.09890).

Suguru Endo Mar 17 2021 02:01 UTC

Our colleague Yasunari had a talk about this topic in March meeting session F32 from 2:23:23, so if you are curious, please watch the presentation! It is still available.

Suguru Endo Mar 16 2021 04:52 UTC

We discussed a similar concept in the paper uploaded to arXiv last October. We used quantum error mitigation for mitigating decoding errors due to failures of error correction and Solovay Kitaev approximation errors. Please check.

https://arxiv.org/abs/2010.03887

Suguru Endo Mar 16 2021 04:50 UTC

We discussed a similar concept in the paper uploaded to arXiv last October. We used quantum error mitigation for mitigating decoding errors due to failures of error correction and Solovay Kitaev approximation errors. Please check.

https://arxiv.org/abs/2010.03887

Élie Gouzien Mar 11 2021 18:18 UTC

Sorry for the inconvenience, it's now updated.

Uncle Al Mar 11 2021 17:08 UTC

Consider chiral tokens and twist odd number traversals (e.g., Berry phase)

Multiple slit matterwave interfere a homochiral molecular beam. Assay the (if any!) interference pattern enantiomer ratio. Hund's paradox: 100% |Left⟩ shoes entering Schrödinger's box exit 1:1 |Left⟩ plus |Right⟩ racemize

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Victory Omole Mar 11 2021 15:58 UTC

The code repository that this paper references is [empty][1].
[1]: https://github.com/ElieGouzien/factoring_with_memory

Ramis Movassagh Mar 06 2021 18:15 UTC

Dear all,

We are excited to see this paper! We would like to point out that complementary results were obtained previously ([arXiv:1909.11769][1] and [arXiv:2004.14397][2]). In particular, an application of these two works is to the non-translationally invariant Ergodic MPS, which vastly general

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anonymoose Mar 06 2021 16:48 UTC

"we have generated one million ***correlated bitstrings with some entries fixed***." So one 'independent sample' from a single (nicely opened!) tensor network contraction?

Brian R. La Cour Mar 06 2021 14:52 UTC

To your last point: It is not known whether the actual performance of future quantum computers would scale adequately to maintain quantum supremacy over this classical algorithm.

Victory Omole Mar 05 2021 16:41 UTC

Towards the bottom of this paper, it says:
> At the same time, our experiments also reflect that Google’s hardware has several advantages over our algorithm. The most significant one is that Google’s hardware is much faster in sampling the quantum circuits with sufficient depth, while our algorithm

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John Smolin Mar 01 2021 21:26 UTC

I think this paper would be improved by mention of the Horodecki's p-bits, which are really the right way to define secrecy from in environment in the quantum setting

Yu Tong Feb 25 2021 22:31 UTC

I think indeed the main issue is the dependence on the confidence level. In Corollary 3 of our paper, as you mentioned, in order to achieve $1-\delta$ confidence level we only need a $\log(\delta^{-1})$ overhead, so the dependence is very weak. In the textbook version of QPE there is a linear $\delt

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Barbara Terhal Feb 25 2021 08:53 UTC

Actually, indeed textbook PE https://arxiv.org/pdf/quant-ph/9708016.pdf does not reach Heisenberg scaling as the total simulation times T scales as T \sim 2^m where m is the number of bits in phase and I think m has to partially scale as like log(1/\delta)=log(1/\epsilon^2) where 1-\delta is confide

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Barbara Terhal Feb 25 2021 08:31 UTC

I agree that MSE is the right quantity (only equal to variance if estimator is unbiased) and I agree with your choice of delta. So in Corollary 3, M has a dependence like \log(\epsilon^{-2}||H||) and you are saying that this only leads to a polylog(\epsilon^-1) factor in the total evolution time so

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Yu Tong Feb 24 2021 17:46 UTC

The reason we can do this in our paper, but not in the setting of 0709.2996, is that they did not assume the error to be bounded. However in most Hamiltonians we care about it is straightforward to obtain a bound on $\|H\|$ that is polynomial in the number of qubits, so we think this is a reasonable

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Yu Tong Feb 24 2021 17:42 UTC

Hello Professor Terhal, thank you for this very nice question! First as you correctly pointed out, we assume we start with a quantum state that only has a non-trivial overlap with the ground state, instead of the exact ground state. With this assumption a lot of phase estimation methods, such as the

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Barbara Terhal Feb 24 2021 07:18 UTC

Hi authors, interesting results! How does your work relate to Heisenberg-limited scaling in Theorem V.1 in https://arxiv.org/pdf/1502.02677.pdf in which one bounds the variance of the estimator. You write that your error is epsilon (which you get with high probability in Corollary 3), but this is no

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Sabee Grewal Feb 24 2021 01:10 UTC

Thanks for the question! Yes, we assume perfect free-fermion states. Also, we only require measurements in the standard basis, and we assume that they are performed without errors.

Thank you for sharing your paper on Fermion Sampling! Yes, based on your results, it appears that we wouldn't be abl

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Michal Oszmaniec Feb 23 2021 12:20 UTC

Very nice paper!

Does the result assume perfect free fermion states or some imperfection is allowed (say in trace distance)?

I also wanted to remark on two of the open problems stated in the end of the paper.

1) Learning pdfs corresponding to superpositions of free states.
I think that it is u

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Johannes Jakob Meyer Feb 17 2021 07:31 UTC

Is this a monotonic (aka non-increasing with respect to quantum channels) distance measure?

Mark M. Wilde Feb 16 2021 20:21 UTC

An important original contribution of this paper is that the author has identified conditions under which the relative entropy of Gaussian states is finite. The conditions depend only on the mean vectors and covariance matrices of the states being evaluated.

Ramis Movassagh Feb 05 2021 01:28 UTC

@Marcel Hinsche. Thank you for your question. I agree that polynomial extrapolation is notoriously ill-conditioned and suffers from the shortcoming you refer to. Our techniques might get you close to O(2^-n/poly(n)) for constant depth circuits but not close enough. Moreover, one loses the anti-conce

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Marcel Hinsche Feb 04 2021 16:47 UTC

Dear authors, if I understand correctly worst-case to average-case reductions via polynomial interpolation cannot possibly extend into the regime of additive errors of size $O(2^{-n}/poly(n))$ that would be needed to close the gap in the hardness of sampling argument for random circuit sampling. Thi

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Joe Fitzsimons Jan 28 2021 07:39 UTC

Robert: I believe in the 2002 paper there is a single additional system that is used to go from qubits to rebits, so locality is not preserved in the translation from qubit systems to rebit systems.

Robert Raussendorf Jan 28 2021 01:57 UTC

How does this fit with
https://arxiv.org/abs/quant-ph/0210187
?

Jalex Stark Jan 27 2021 17:33 UTC

If I understand correctly, the authors have made a grand achievement in experimental quantum foundations. Congratulations!

My understanding is as follows:
They construct something like a
tripartite Bell inequality [0], whose maximal violation is achieved with only 4 qubits. Any experimental

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Casper Gyurik Dec 18 2020 14:57 UTC

Today an updated version of the paper has been uploaded to arXiv. We have added new quantum algorithms along with complexity-theoretic evidence for the classical intractability of the underlying problems, we have identified families of instances (i.e., graphs) with a quantum speedup, and we have imp

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Nengkun Yu Nov 30 2020 19:36 UTC

Problem solved.

Markus Heinrich Nov 30 2020 08:58 UTC

Since today, an updated version of the paper is available on the arXiv. Besides having fixed the grammar mistake in the title, we have been able to extend our argumentation to show that the classes are already distinct for $n \geq 2$ qubits ($n\geq 3$ in v1) and agree for $n=1$.

Nengkun Yu Nov 30 2020 08:36 UTC

There seems to be an issue with the arXiv tex engine.
No idea why the system accepted our submission in the first place,
when everything seemed OK, but cannot compile it now.

However, it _does_ produce perfectly good Postscript, which you
can then convert to pdf or any other format.

Jiayu Zhang Nov 21 2020 01:46 UTC

I just realized arXiv does not favor frequent version updates... My update frequency is limited to once per month. See my personal website for the most recent version (which contains some typo fixes and font change etc compared to the previous versions) and sorry for the possible bothering.

Since

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Jiayu Zhang Nov 17 2020 19:43 UTC

(Updates: improved talk in https://www.youtube.com/watch?v=ri8uOOreEJU after a little bit of practicing. Resources in http://cs-people.bu.edu/jyz16 )