...(continued)You introduce some very interesting concepts in this paper! I just wanted to point out some connections that might be interesting to explore.
**Hamiltonian complexity**
The density matrix in your eq. (2) looks exactly like 2-local Hamiltonian that encodes classical computation in its ground state
...(continued)Granted that it would yield a different story if A were to perform the interference experiment instead, but it's certainly a story quantum mechanics allows us to tell---and that story depends on $z$ being indefinite in value. And one could also tell a combined story, in which A randomly chooses whet
...(continued)Since I can imagine two reasons for why you think that a statement such as $(\text{n:20}, *, z, *) \in s^A$ could be problematic, let me make two remarks that may clarify this point. The first is that the experiment A (the one that experimenter A wants to analyse) consists *by definition* of a measu
Makes sense! Thank you for all the explanations and clarifications, I really appreciate it. Cheers
This is a nice result!
...(continued)Thank you for taking the time to answer my question, I really appreciate it. However, I'm sorry but unfortunately, I'm still not quite sure I get it---basically, I don't understand how, e.g., $(n: 20,\psi_C,z,*)$ can be a 'plot point' of A's story. I mean, during the time interval $(n:20,n:30)$ (i.e
...(continued)Yes, you have understood correctly, I would say. One intuitive way to think about this is to “halt” the experiment already at time t = n:30, after A has seen outcome x, and ask yourself what statements A can now make. At this time, the measurement of z has been carried out, so A (although he hasn’t
...(continued)The question whether two statements, S1 and S2, are "contradictory" is, in my opinion, independent of whether they are experimentally testable. Let me propose another example to illustrate this. A theory about atomic physics may allow us to derive the two statements S1 = “If the Coulomb constant was
...(continued)Hi Renato. After reading the paper and following our discussion, I have some comments. Being large, I put them on my blog:
[http://www.unitaryflow.com/2016/05/are-single-world-interpretations-of-quantum-theory-inconsistent.html][1][1]: http://www.unitaryflow.com/2016/05/are-single-world-int
...(continued)I guess what I am really asking/wondering is whether it's legitimate to characterize theories as "inconsistent" in this context, as this term is commonly used to characterize theories that are self-contradictory when it comes to observable quantities. Otherwise, how would it be possible to have an
...(continued)Interesting paper. I'm not yet quite done digesting it, but one thing that trips me up is that from the point of view of A, before they do any measurement, it seems the whole system of F1 + F2 should be described by some superposition; in particular, the outcome of F2's measurement is not definite.
...(continued)If I understand correctly, you are asking whether one should be worried if a theory leads to conclusions that are inconsistent, but which we cannot experimentally test directly. I think the answer is yes, for the same reason as I would for example be worried about a theory that tells me both “there
...(continued)Thanks a lot for the detailed explanation.
If I may call *A = (r = tail ==> w **?** ok)* a parameter that can take two values, then A is a free parameter of the theory and its value does not affect anything that is observable. Many theories may have such unobservable free parameters; e.g., cla
...(continued)Excellent point. To start with your last question: Self-consistency of a theory T means that it does not make statements that contradict themselves. For example, in the Extended Wigner’s Friend gedankenexperiment described in the paper, it could happen that one may use a theory T in a certain way to
...(continued)Hi Renato,
it's great that you follow this site and reply to questions. Can i ask you the following, as it is very counter-intuitive to me and central to your paper: How is it possible to have two theories T1 and T2 that give exactly the same experimental predictions, but T1 is self-consistent whi
"... two parties, usually referred to as Alessandro and Bruno... "
Exactly.
Who ordered that ??
If I understand correctly, the result implies that quantum physics cannot consistently describe the macroscopic world, unless there are many of them.
...(continued)For inspiration, [here][1] is the first editorial of a newly created open access linguistics journal called *[Glossa][2]*. This journal was established after the editorial board of another journal called *[Lingua][3]* resigned en masse after a disagreement with their owner Elsevier about the pricing
I'm thrilled that John will finally publish his book.
Scotland has a strong record of inspiring and inspired physicists ;-)
It is amazing that G. Nadurra has contributed to your research despite being just 16 years old!
Interesting work... Could you please comment on possible connections of your work with those of Hayden and May (http://arxiv.org/abs/1210.0913) and of Portmann et al. (http://arxiv.org/abs/1512.02240)?
This is a beautiful set of lecture notes.
...(continued)What I mean is that merely separating the process by which you choose each measurement setting and the entangling event does not actually close even this restricted version of the loophole. You need a further assumption that this choosing process produces a distribution of outcomes which are uncorre
No worries at all! I think I pressed the wrong button :-) And it is good to see that my answer was not totally off!
Okay, I don't disagree. You seem to be implying that making this split is artificial? Why should this be the case for setting dependence (freedom of choice) but not for outcome dependence?
Oops! I see your answer now. Didn't mean to dupe it...
I put in a feature request for sorting comments by date.
https://github.com/scirate/scirate/issues/328
I had answered in a similar fashion (a second answer after a first answer), but also my comment is floating around :-)
Note: Because I hit the wrong button, there's a stray comment (by me) floating around that answers this question. It's just not in this thread...
...(continued)Good point about sorting ...but it wouldn't have been an issue if I'd used the site correctly! I intended my comment to be a reply to Tom's, but (due to incompetence) it ended up standalone instead. Oops. Anyway, SciRate does keep threads together, which should go some way to helping with organiz
That would indeed be helpful - you should definitely email the developers about this! Not sure if they read every comment ;-)
Thanks, Robin!
I like this use of SciRate as a "reading group." It's a collaborative and friendly use of the comments.
Perhaps SciRate can add a feature to "sort by date" rather than by rating/points, which would be useful for such discussions?
...(continued)@Tom: They're considering the case where U's eigenvalues are not discrete, but (instead) take values that are dense on the complex unit circle. So for every $\phi\in[0,2\pi]$, U has an eigenvalue $e^{i\phi}$. Which means that the spectrum isn't just *contained* in [-2,2], it *is* [-2,2]. The who
...(continued)Sure, but if you don't rule out super-determinism, then you haven't closed the loophole, you are merely splitting it in two and then closing one of those. There is no way to do what you are suggesting without introducing an additional assumption. Even in a universe that is not super-deterministic, h
...(continued)Hi Joe,
Well, yes and no. It really depends on whether or not you say the measurement choices can be pre-determined from the beginning of the universe (superdeterminism), or whether they are - for example - potentially determined from the moment of entanglement creation. In the later case the loo
I would like to bring to your attention that fig 2.(a) is inconsistent with it's caption. Is T=50 or T=20?
It's fundamentally impossible to close. There is never a way to rule out super-determinism.
Also, there is still no mention of the freedom of choice loophole. But maybe this is even something that is impossible to close in their setup?
...(continued)This result has caused quite a lot of excitement in number theory (see the articles in [Quanta Magazine][1] and [Nature News][2]).
It turns out that the last digits of consecutive primes are not uniformly distributed but rather tend to be anti-correlated. For example, in base 10 the last digit of
Wow, that's really great! I wasn't expecting that progress on this will be made any time soon, so it's great to hear that somebody is already working on this and trying to change things!
...(continued)Marcus Huber, Christian Gogolin and I are actually in the process of setting up an arXiv overlay journal for quant-ph. We are finalizing a draft with the initial proposal and guidelines, and will soon reach out to form an editorial board and open the idea to discussion by the community. More news on
...(continued)I don't even really see the point of a journal. Maybe we could adapt SciRate to have a little collection of longer reviews/editorials/etc associated to each article (like comments).
What do you think a journal would offer over SciRate itself? I.e. if the potential paper reviewers would just inste
Gower's [earlier post][1] on this arXiv overlay initiative is also very inspiring.
[1]: https://gowers.wordpress.com/2015/09/10/discrete-analysis-an-arxiv-overlay-journal/
...(continued)An arXiv overlay journal was also started for [astrophysics][1], and their source is available on [GitHub][2]. All we need to do is find/replace "astrophysics" with "quantum information" in the source code, and we have a platform.
[1]: http://astro.theoj.org/about
[2]: https://github.com/o
...(continued)This article just got published in [Discrete Analysis][1], a new arXiv overlay journal that was launched last week (by "published" I simply mean that you can read it for free on arXiv as you would normally do anyway). Just like in any other journal, this article was peer-reviewed, revised, accepted,
A dream that started during my PhD keeps getting closer and closer to reality! :-)
Braneshop, and
the US National Science Foundation.
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