...(continued)Well, one answer to that question is that a memory recording (or recording of a preparation) is so redundantly encoded in the environment, that it is practically impossible to undo it. Of course, one could theoretically undo it, by performing the operation on all the copies of the information, which
Note that A and W carry out their measurements at the end of the experiment (i.e., there is no further measurement). The resulting entanglement is hence irrelevant.
...(continued)Interesting question. But doesn't “recording a value” mean that we prepare a system (the “memory system”) in a certain state and then assume that it will stay in that state? So, unless we make a distinction between “memory systems” and “normal quantum systems”, the potential problem you are mentioni
...(continued)Thanks. So, taking the example of a quantum contextuality proof where I undo one of the measurements, is it fair to say that the distinction you are making with your experiment, is that the thing which is undone is a preparation and not a measurement? Is it not just as problematic to ascribe values
...(continued)Thank you for clearing that up. But wouldn't the entanglement with A and W creates an external record of the states of F1 and F2' labs and bring me back to the same problem? That is, starting from $ |T\rangle |\downarrow \rangle |\text{ok} \rangle_{AW} $, to infer $ |T\rangle |\rightarrow \rangle |\
...(continued)Note that states of the form $|\downarrow\rangle_{F2}$ are meant to be states of the entire lab of experimenter F2. (I am sorry if this was unclear.) Hence, in the particular case you mention, the electron is automatically included in the description because it is within F2's lab. But you are of cou
...(continued)Hi. I'm also worried about erasing a measurement record but in the inferential step (26)=>(35).
The gist of the argument seems to lie entirely in these two terms of the Hardy state (ignoring the normalization): $$ |T\rangle |\uparrow \rangle + |T\rangle |\downarrow \rangle = |T\rangle |\rightarrow
...(continued)The crucial fact to notice is that the derivation of Eq. 25 relies entirely on standard quantum mechanics (applied from the viewpoint of F1): If a system is prepared in a state $\psi$ and subsequently evolves according to a unitary $U$ then its state will be $U \psi$ (and a measurement will give an
...(continued)Yes, exactly -- thanks for the prompt response. Lluis Masanes observed further that by invoking special relativity, one can have different observers who would make different statements about actual measurement records that would be consistent in their reference frame, but if they tried to get togeth
...(continued)at first I tried to satisfy the chiral symmetry, in that place, I thought that the chiral symmetry breaking is due to vacuum classical polarization, and this problem is solved by dual behavior of fields, some of these notes are in the first paper http://iiste.org/Journals/index.php/APTA/article/view
...(continued)Regarding your question about the measurement records: You are right that the values r, z, x, and w are not at the same time available. But r and z, for instance, can be accessed simultaneously (at time n:20), which justifies the statements involving only these two (e.g., our Eq. 26). The same holds
...(continued)Hi Renato, yours and Daneila's paper has generated a lot of discussion, and today, Will Matthews presented it to our group at UCL. A question: in deriving the contradiction are you not ascribing results to measurements which are later undone/erased? So at the end of the experiment, there is no measu
...(continued)Hi Marco,
Thank you very much for taking the time to reply to my message! I really appreciate it! I think I fully understand what you mean until now. We should state the notion of cone and the relation between our results and the notion of cone. We will try to give an objective and precise expres
Great figures! Looking forward to reading this one.
...(continued)at first I tried to remove x1=x2 from the propagation
https://www.docdroid.net/TYzB01L/the-time-stop-in-the-quantum-fields-fluctuation.pdf.html
the propagation modification is legal according to remove x1=x2
to satisfy the symmetries I related that modification to dual fields behavior, as I think
...(continued)Hi Bang-Hai,
thank you for your message, and my apologies: I have intermittent internet connection and a decently long reply of mine got lost because of that :-( Unfortunately I do not have the time to rewrite it in full.
What I meant is that people have known for quite some time about the du
...(continued)Hi Marco,
Right! Thank you for your mathematical explanations and clarifications, I really appreciate it! Could we add your pointing to our new version?
Frankly, we try to clarify more notions and results and connections among them, physically, not mathematically (It is also the reason that we ha
...(continued)I am not sure where this goes (I have only skimmed through the first part of the paper), but what the author seems to find unexpected is the notion of cone dual to a cone, and the fact that the cone of positive operators is self-dual, while entanglement witnesses are dual to separable operators, etc
Some of the figures in your bound entanglement paper look spookily like some of our graphs! Thanks for highlighting these connections Māris, I appreciate it.
...(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
Braneshop, and
the US National Science Foundation.
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