...(continued)The ability to impose a "cut" and isolate a system (e.g., a single H atom) from its surroundings and treating that system as a quantum object disconnected from its surroundings, or connected to them solely by means of classical channels, is an extremely convenient fiction. But it is, at the end of t
...(continued)My previous statement must have been ambiguous. But when I wrote that an experimenter applies quantum theory to a system, I did not mean to imply that she applies classical theory to its surroundings. Rather, the idea was that she can use QT to study any arbitrary subsystem of the universe, provided
...(continued)My understanding of quantum theory is precisely that: It must be applied to the experimenter themselves as well as the apparatus. I come from the school of thought that believes that everything is quantum.
As per my previous comment, within this framework it may be possible that your paper could
Indeed, our argument is based on the idea that any experimenter is free to use quantum theory to describe the world *around* her (but not including herself). If I now understand correctly, you are saying that this is not in general a correct use of quantum theory. Did I get this correctly?
I don't think that QIC is to blame here. ECCC is also not indexed by google scholar for some strange reason. Try this paper http://eccc.hpi-web.de/report/2016/073/ for instance.
...(continued)You are perfectly right; that is exactly what confused me.
Personally, then, I feel slightly uneasy with saying that your property QT captures quantum mechanics, since I believe strongly that quantum mechanics must describe the state of the experimenter themselves. This is especially pertinent in
...(continued)I agree with what you are writing about $\psi_L$. While the state of the prepared system $S$ does not depend on whether $E$ remembers it, the state $\psi_L$ (which includes $E$) does.
I am not sure though what you meant when you wrote that $\psi_L$ is the "relevant object". Note that property QT
...(continued)Actually, the Bayesian perspective did not enter my mind.
I *almost* agree with the reformulation you give in your second paragraph. I say "almost" because of one detail that I feel is important in the context of your paper, and which for me is the key issue at stake here.
Suppose I have a lab
...(continued)I am not sure why you think that the state $\psi$ must change. But one guess I have (please correct me if I am wrong) is that you take a Bayesian perspective, in which case there may be an ambiguity in the interpretation of time t. So, maybe, you interpreted t as the time when the prediction was mad
...(continued)This paper somehow got published in QIC. Not that I would encourage anyone to read it, but let's say you wanted to...
Well, you would probably just [look up][4] the published version on Google Scholar.
What a bummer(!), it's not there... Maybe that's just because the paper's name has changed?
...(continued)Dear Renato, may I also join the chorus and thank you for being so accessible and willing to discuss your results publicly. I've been following this thread since its inception but have so far resisted contributing.
Please correct me if I am wrong, but does not a full description of $\psi$ require
...(continued)looks like a nice paper. People have looked at how to do wavelets with quantum circuits and i don't see any of these papers referenced, i.e.
http://arxiv.org/abs/quant-ph/9702028
http://arxiv.org/abs/quant-ph/0001077
http://arxiv.org/abs/quant-ph/9909014
so how different are the quantum circuits
...(continued)Practicalities are indeed irrelevant here, so we can certainly focus on the last question you pose. But let me first restate more precisely what we use in our argument. In the special case of a system with trivial Hamiltonian between time t=0 and t=1, the relevant statement reads as follows: “If an
...(continued)I have a question, relates to:
However, since the non-gravitational physics has been accurately explained by the principles of quantum mechanics, it seems necessary that General Relativity is merged with quantum mechanics.
but the quantum principles at first emerged from boundary conditions in th
...(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... "
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the US National Science Foundation.
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