Recent comments from SciRate

Alvaro M. Alhambra Jul 24 2017 16:10 UTC

This paper has just been updated and we thought it would be a good
idea to advertise it here. It was originally submitted a year ago, and
it has now been essentially rewritten, with two new authors added.

We have fixed some of the original results and now we:
-Show how some fundamental theorem

gae Jul 21 2017 17:58 UTC

Dear Marco, indeed the description in those two papers is very general because they treat both DV and CV channels. However, things become "easier" and more specific if you restrict things to DVs. In this regard, let me point you at this paper , in particular to

Marco Piani Jul 21 2017 16:33 UTC

Is it really the case for the general definition of teleportation-covariant channel given in or ? I understand that there special classes of teleportation-covariant channels are considered where what you say holds (that is, for pairs

gae Jul 21 2017 15:51 UTC

If two channels are teleportation-covariant and between Hilbert spaces with the same dimension, then the correction unitaries are exactly the same. For instance, for any pair of Pauli channels (not just a Pauli and the identity), the corrections are Pauli operators.

Marco Piani Jul 21 2017 15:36 UTC

Is it more precisely that the result holds for any pair of *jointly* teleportation-covariant channels? The definition of teleportation-covariant channel (according to what I see in ) is such that the covariance can be achieved with a unitary at the output that depend

gae Jul 21 2017 14:01 UTC

Thx Steve for pointing out this paper too, which is relevant as well. Let me just remark that the PRL mentioned in my previous comment [PRL 118, 100502 (2017), ] finds the result for any pair of teleportation-covariant channels (not just between a Pauli channel and t

Steve Flammia Jul 21 2017 13:43 UTC

Actually, there is even earlier work that shows this result. In [arXiv:1109.6887][1], Magesan, Gambetta, and Emerson showed that for any Pauli channel the diamond distance to the identity is equal to the trace distance between the associated Choi states. They prefer to phrase their results in terms

Stefano Pirandola Jul 21 2017 09:43 UTC

This is very interesting. In my reading list!

gae Jul 21 2017 09:00 UTC

In relation with the discussion at page 21 of this paper. Consider depolarizing channels (including the trivial case of the identity channel) which are teleportation covariant as in the definition Eq. (9) of [Nature Communications 8, 15043 (2017)]. The diamond norm b

Chris Ferrie Jul 18 2017 02:32 UTC

Since arXiv now supports supplementary material, we did not host the source externally. The easiest way to view the code is using

By the way, if you are having difficulty navigating

Ashley Jul 14 2017 20:02 UTC

Thanks! Yes, I think a generalisation of this form ought to work, though I didn't work out the details.

Vlad Gheorghiu Jul 14 2017 18:11 UTC

Nice result! It looks like the technique is easily generalizable to qudits, isn't it, by replacing the bell states with $|b_{ij}\rangle = (X^iZ^j \otimes I) \frac{1}{\sqrt{D}}\sum_{k=0}^{D-1}|kk>$, where $X|i\rangle=|i\oplus1>$ and $Z|i\rangle=\omega^i|i\rangle$? Fo course $\mathbb{F}_2^n$ will beco

Blake Stacey Jul 11 2017 16:27 UTC

Eight hundred forty-four!

C. Jess Riedel Jul 04 2017 21:26 UTC

Even if we kickstart evolution with bacteria, the amount of time until we are capable of von Neumann probes is almost certainly too small for this to be relevant. See for instance [Armstrong & Sandberg]( It

Noon van der Silk Jun 29 2017 23:51 UTC

Wow, from one-way QC to AI! :)

xecehim Jun 27 2017 15:03 UTC

It has been [published][1]


Kenneth Goodenough Jun 21 2017 12:48 UTC

Ah yes I see, thank you for the clarification!

Stefano Pirandola Jun 20 2017 13:26 UTC

Hi Kenneth, more precisely that plot is for a particular "Pauli-damping" channel, i.e., a qubit channel that is decomposable into a Pauli channel (1) and an amplitude damping channel (2). This "Pauli-damping" channel can be simulated by performing noisy teleportation over a resource state that corre

Kenneth Goodenough Jun 20 2017 12:47 UTC

Interesting work! I was wondering, how do the new upper bounds for the amplitude-damping channel in Fig. 2 compare to previous bounds?

Barbara Terhal Jun 20 2017 07:25 UTC

It would be good if this conflict on assigning priority and credit is peacefully resolved by the parties involved (i have no opinions on the matter).

Stefano Pirandola Jun 15 2017 05:32 UTC

The secret-key capacity of the pure-loss channel -log(1-t) was proven in [9], not in the follow-up work [13] (which appeared 4 months later). Ref. [13] found that this capacity is also a strong converse bound, which is Eq. (1) here. Same story for Eq. (4) that was proven in [9], not in [13]. Again t

Chris Ferrie Jun 09 2017 10:06 UTC

I have posted an open review of this paper here:

Eddie Smolansky May 26 2017 05:23 UTC

Updated summary [here](

# How they made the dataset
- collect youtube videos
- automated filtering with yolo and landmark detection projects
- crowd source final filtering (AMT - give 50 face images to turks and ask which don't belong)
- quality control through s

Felix Leditzky May 24 2017 20:43 UTC

Yes, that's right, thanks!

For (5), you use the Cauchy-Schwarz inequality $\left| \operatorname{tr}(X^\dagger Y) \right| \leq \sqrt{\operatorname{tr}(X^\dagger X)} \sqrt{\operatorname{tr}(Y^\dagger Y)}$ for the Hilbert-Schmidt inner product $\langle X,Y\rangle := \operatorname{tr}(X^\dagger Y)$ wi

Michael Tolan May 24 2017 20:27 UTC

Just reading over Eq (5) on P5 concerning the diamond norm.

Should the last $\sigma_1$ on the 4th line be replaced with a $\sigma_2$? I think I can see how the proof is working but not entirely certain.

Noon van der Silk May 23 2017 11:15 UTC

I think this thread has reached it's end.

I've locked further comments, and I hope that the quantum computing community can thoughtfully find an approach to language that is inclusive to all and recognises the diverse background of all researchers, current and future.

I direct your attention t

Varun Narasimhachar May 23 2017 02:14 UTC

While I would never want to antagonize my peers or to allow myself to assume they were acting irrationally, I do share your concerns to an extent. I worry about the association of social justice and inclusivity with linguistic engineering, virtual lynching, censorship, etc. (the latter phenomena sta

Aram Harrow May 23 2017 01:30 UTC

I think you are just complaining about issues that arise from living with other people in the same society. If you disagree with their values, well, then some of them might have a negative opinion about you. If you express yourself in an aggressive way, and use words like "lynch" to mean having pe

Steve Flammia May 23 2017 01:04 UTC

I agree with Noon that the discussion is becoming largely off topic for SciRate, but that it might still be of interest to the community to discuss this. I invite people to post thoughtful and respectful comments over at [my earlier Quantum Pontiff post][1]. Further comments here on SciRate will be

Noon van der Silk May 23 2017 00:59 UTC

I've moderated a few comments on this post because I believe it has gone past useful discussion, and I'll continue to remove comments that I believe don't add anything of substantial value.


Aram Harrow May 22 2017 23:13 UTC

The problem with your argument is that no one is forcing anyone to say anything, or banning anything.

If the terms really were offensive or exclusionary or had other bad side effects, then it's reasonable to discuss as a community whether to keep them, and possibly decide to stop using them. Ther

stan May 22 2017 22:53 UTC

Fair enough. At the end of the day I think most of us are concerned with the strength of the result not the particular language used to describe it.

VeteranVandal May 22 2017 22:41 UTC

But how obvious is ancilla? To me it is not even remotely obvious (nor clear as a term, but as the literature used it so much, I see such word in much the same way as I see auxiliary, in fact - now if you want to take offense with auxiliary, what can I say? I won't invent words just to please you).

VeteranVandal May 22 2017 22:21 UTC

I don't think science can or should avoid the perpetuation of existing "historical unequal social order" by changing the language, as to me it seems that, if you try hard enough you can find problem with anything you want to be offended at - rationalizations are tricky things you can often get carri

Fernando Brandao May 22 2017 21:37 UTC

I am not sure if the ArXiv is the best venue for this kind of paper/rant. Also, I’m concerned that so much energy is being put into the discussion. As a non-native speaker, I might not get all nuances of the language, but I have a hard time understanding why we should drop a scientific jargon like “

Toby Cubitt May 22 2017 21:25 UTC

I'm sorry if my comment came across to you as "authoritative" or aggressive. It was intended in the spirit of scholarly debate, and is of course as subjective and completely non-authoritative as anything else written here: your comment, the original article, and this reply! Karoline and I were frien

Steve Flammia May 22 2017 21:24 UTC

@Ancilla, you're welcome to contribute your opinion here, but you have to respect the [moderation guidelines][1]. You have made repeated personal insults to people posting here (calling them "twisted", "unhinged", "slow thinkers", etc.) and any more such conduct is going to end with me deleting the

er May 22 2017 21:16 UTC

Oh, I wasn't suggesting that anyone offended was merely looking to take offense. However, the author specifically mentions (for example) "racial segregation", something that, although I cannot claim to know for certain, I'm assuming they have little experience of. Hence: the act of taking offense on

Alvaro M. Alhambra May 22 2017 21:01 UTC

Sorry but how is language not a significant part of the "underlying systemic issues"?

Steve Flammia May 22 2017 20:38 UTC

@Stan, I think that it is misplaced to think that anyone is calling for *censorship*. (Certainly I am not, and I don't support censorship at all.) It is just that we as a community are choosing to create this language, and we have the option to use whatever term we like. Why should we choose a term

stan May 22 2017 20:28 UTC

I can see both sides of the argument, but so far find the proof unconvincing for censorship.

If we want to make science "unoffensive", there are *many* potentially "offensive" terms - 'retarded potentials' in E&M, 'dominating sets', etc. Do we accept that language evolves and thus rewrite scient

Peter Love May 22 2017 20:26 UTC

The connotation I thought of when I first heard this term was Air supremacy (which is distinct from air superiority in the same way that quantum supremacy is distinct from quantum advantage). Then Trump got elected. Now hearing "quantum supremacy" is like poking at a broken tooth with a metal spike.

Steve Flammia May 22 2017 19:48 UTC

Aram, I think the case you are making is the best possible case for keeping the term. That said, the term "quantum supremacy" clearly touches a nerve with some large number of people, whereas I haven't observed that with any of the other terms you've mentioned. So there is some weakness in your argu

Aram Harrow May 22 2017 19:26 UTC

I think sampling and analog simulation are clearly within the scope of "computational." The way I see it is that they do something which is information-theoretically possible with classical computers but would take them too long. So it would exclude precision measurement, but include a cold-atom s

Aram Harrow May 22 2017 19:22 UTC

I get that these words may remind us of something bad, but it doesn't follow that they cause any actual bad effects. For example, they don't strengthen white supremacist groups (as far as I can tell) or make racial minorities feel unwelcome (as far as I can tell). Words have multiple meanings, som

John Preskill May 22 2017 19:12 UTC

I didn't mean capacity or Bell inequalities. I meant that (for example) "computational" might be inferred to include digital but not analog quantum simulators, or to exclude (say) boson sampling, while I had intended for "quantum supremacy" to encompass both. Perhaps I hear it that way because "comp

Um May 22 2017 18:59 UTC

Thanks Er. That sounds to me like a much more coherent argument than the one made in the comment. My main problem with the comment was the author's claim that it was "nonsensical" and had no merit (and the attempt to invalidate the use of the term incorrectly). I agree that perhaps replacing the ter

Barbara Terhal May 22 2017 18:53 UTC

But i also agree that it is not easy to come up with an alternative term which captures both the breadth of the 'advantages' & the possible break-through character of them.

Steve Flammia May 22 2017 18:51 UTC

Regarding the narrowing of the scope by adding "computational", I think that this has somehow already happened with just the original term. I've never heard anyone use the term QS in the context of, say, a Bell experiment or the classical capacity of a quantum channel.

Barbara Terhal May 22 2017 18:41 UTC

it is not even about being directly offensive to other people, i simply can't get myself to say 'quantum supremacy', it suggests some superiority involving human beings (the whole field of QC hitting other people over the head with their 'quantum-supreme experiments').
I mean how do you read a pop